RSV vaccines (Arexvy RSVPreF3 OA, Abrysvo RSVpreF, mResvia mRNA-1345), maternal RSVpreF, and nirsevimab (monoclonal antibody)

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disease risks

post-acute and long-term sequelae

vaccine efficacy and effectiveness

vaccine safety and adverse events

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RSV lower respiratory tract infection in infants and young children Respiratory syncytial virus

Disease risks

Acute risks of the infection itself: complications, hospitalisation, ICU, death.

Outcome (O)	Population (P)	Estimate	Design (S)	Source
Share of infant RSV-ALRI hospitalisations occurring in preterm infants severity: hospitalisation case definition: RSV-associated acute lower respiratory infection hospital admissions, children under 2 years	infants of any gestational age, under 2 years risk group: preterm birth (before 37 weeks) vaccination status: unvaccinated country: global period: 2019 NeonateInfant <1y1-4y	25 (16–37) proportion of all infant RSV-ALRI hospitalisations in preterm infants (%) per RSV-ALRI hospitalisation in infants	meta-analysis	Wang et al. 2024 Lancet quote Overall, preterm infants accounted for 25% (95% UR 16-37) of RSV-associated ALRI hospitalisations in all infants of any gestational age. abstract, FINDINGS Uncertainty range, not a 95% CI. In-hospital case fatality in preterm infants was similar to all infants per the same abstract; the excess is in admission rate, not in death once admitted.
RSV-ALRI hospitalisation in the second year of life, early preterm vs all infants severity: hospitalisation case definition: RSV-associated acute lower respiratory infection hospital admission	children aged 12-23 months risk group: early preterm birth (<32 weeks gestational age) vaccination status: unvaccinated country: global period: 2019 1-4y	2.26 (1.27–3.98) rate ratio vs all infants and young children of any gestational age ratio of hospitalisation rates	meta-analysis	Wang et al. 2024 Lancet quote In the second year of life, early preterm infants and young children had a similar incidence rate but still a significantly higher hospitalisation rate (RR 2·26 [95% UR 1·27-3·98]) compared with all infants and young children. abstract, FINDINGS Uncertainty range, not a 95% CI. Relevant to whether early preterm infants need protection into a second RSV season.
Case fatality among US children under 5 with RSV severity: death case definition: Proportion of deaths among RSV cases, mostly inpatient, varied RSV definitions across 15 studies	infants and children younger than 5 years vaccination status: unvaccinated country: United States setting: mostly hospital period: studies through 2013 NeonateInfant <1y1-4y	0 to 1.7 CFR (%) per RSV case (mostly hospitalised)	systematic review	Bylsma et al. 2022 J Infect Dis quote CFRs ranged from 0% to 1.7% for RSV (n = 15) and from 0% to 0.17% for ACB (n = 6); higher CFRs were reported among premature, intensive care unit-admitted, and publicly insured infants and children. abstract, RESULTS A range across studies, not a pooled estimate or CI. Higher CFRs were in premature, ICU-admitted and publicly insured children. No study reported a population RSV mortality rate.
RSV-associated hospitalisation, children under 5 years severity: hospitalisation case definition: RT-PCR confirmed RSV among children admitted with acute respiratory illness at 7 paediatric hospitals, population-based surveillance	children younger than 5 years vaccination status: unvaccinated country: United States setting: hospital, population-based surveillance period: 2016-2020 n: 13 524 inpatients screened, 4243 RSV-positive NeonateInfant <1y1-4y	4.0 (3.8–4.1) hospitalisation rate per 1000 children per year per 1000 children under 5 years per year	surveillance	Curns et al. 2024 Pediatrics quote The average annual RSV-associated hospitalization rate was 4.0 (95% confidence interval [CI]: 3.8-4.1) per 1000 children <5 years, was highest among children 0 to 2 months old (23.8 [95% CI: 22.5-25.2] per 1000) and decreased with increasing age. abstract, RESULTS Pre-nirsevimab and pre-maternal-vaccine baseline in a high-income setting. The rate by month of age in the next record is six times higher.
RSV-associated hospitalisation, infants aged 0-2 months severity: hospitalisation case definition: RT-PCR confirmed RSV among children admitted with acute respiratory illness, population-based surveillance	infants aged 0 to 2 months vaccination status: unvaccinated country: United States setting: hospital, population-based surveillance period: 2016-2020 NeonateInfant <1y	23.8 (22.5–25.2) hospitalisation rate per 1000 children per year per 1000 infants aged 0-2 months per year	surveillance	Curns et al. 2024 Pediatrics quote The average annual RSV-associated hospitalization rate was 4.0 (95% confidence interval [CI]: 3.8-4.1) per 1000 children <5 years, was highest among children 0 to 2 months old (23.8 [95% CI: 22.5-25.2] per 1000) and decreased with increasing age. abstract, RESULTS Rate decreased with increasing age per the same sentence. Roughly one in forty infants in this age band were hospitalised with RSV each year before prevention products.
RSV-associated hospitalisation, premature vs term children severity: hospitalisation case definition: RT-PCR confirmed RSV among children admitted with acute respiratory illness	children younger than 5 years risk group: premature birth vaccination status: unvaccinated country: United States period: 2016-2020 NeonateInfant <1y1-4y	1.95 (1.76–2.11) rate ratio, premature vs term per 1000 children per year (ratio of rates)	surveillance	Curns et al. 2024 Pediatrics quote Higher RSV-associated hospitalization rates were found in premature versus term children (rate ratio = 1.95 [95% CI: 1.76-2.11]). abstract, RESULTS Two-thirds of RSV-positive inpatients in this surveillance had no underlying condition or prematurity, so the higher rate in preterm infants does not mean term infants are spared.
ICU admission among RSV-positive inpatients, age 0-2 months vs 24-59 months severity: ICU admission case definition: ICU admission among children hospitalised with RT-PCR confirmed RSV	0 to 2 months, compared with 24-59 months vaccination status: unvaccinated country: United States setting: hospital period: 2016-2020 NeonateInfant <1y	1.97 (1.54–2.52) adjusted OR for ICU admission vs children aged 24-59 months per RSV-positive inpatient	surveillance	Curns et al. 2024 Pediatrics quote Risk factors for ICU admission among RSV-positive inpatients included: age 0 to 2 and 3 to 5 months (adjusted odds ratio [aOR] = 1.97 [95% CI: 1.54-2.52] and aOR = 1.56 [95% CI: 1.18-2.06], respectively, compared with 24-59 months), prematurity (aOR = 1.32 [95% CI: 1.08-1.60]) and comorbid conditions (aOR = 1.35 [95% CI: 1.10-1.66]). abstract, RESULTS Denominator is hospitalised RSV cases, not all infants; do not multiply by the hospitalisation rate to get a population ICU risk. Prematurity (aOR 1.32) and comorbidity (aOR 1.35) are in the same sentence.
RSV hospitalisation, infants aged 1 month severity: hospitalisation case definition: RT-PCR confirmed RSV acute respiratory illness, prospective population-based surveillance, population stratified by month of age	infants aged 1 month vaccination status: unvaccinated country: United States setting: hospital, population-based surveillance period: October-March, 2000-2005 n: 2149 enrolled hospitalised children, 559 RSV-infected NeonateInfant <1y	25.9 hospitalisation rate per 1000 children per 1000 infants aged 1 month per season	surveillance	Hall et al. 2013 Pediatrics quote The highest age-specific rate was in infants 1 month old (25.9 per 1000 children). abstract, RESULTS Pre-vaccine-era baseline with month-of-age resolution. The average across all children under two years in the same abstract is about a fifth of this.
RSV hospitalisation, infants aged 2 months or younger severity: hospitalisation case definition: RT-PCR confirmed RSV acute respiratory illness, prospective population-based surveillance	infants aged 2 months or younger vaccination status: unvaccinated country: United States setting: hospital, population-based surveillance period: October-March, 2000-2005 NeonateInfant <1y	17.9 hospitalisation rate per 1000 children per 1000 infants aged 0-2 months per season	surveillance	Hall et al. 2013 Pediatrics quote Infants ≤ 2 months of age, who comprised 44% of RSV-hospitalized children, had a hospitalization rate of 17.9 per 1000 children. abstract, RESULTS These infants were 44% of all RSV-hospitalised children in the study.
Previously healthy children as a share of RSV hospitalisations severity: hospitalisation case definition: RT-PCR confirmed RSV acute respiratory illness in hospitalised children under 24 months	children younger than 24 months vaccination status: unvaccinated country: United States setting: hospital period: 2000-2005 NeonateInfant <1y1-4y	79 proportion of RSV-hospitalised children with no risk factors (%) per RSV-hospitalised child	surveillance	Hall et al. 2013 Pediatrics quote Most children (79%) were previously healthy. abstract, RESULTS The reason risk-factor-targeted prophylaxis (palivizumab era) could not prevent most RSV admissions, and why universal infant programmes were adopted.
In-hospital death among RSV-associated admissions, children under 2 years severity: death case definition: ICD-9-CM diagnosis codes for RSV infection in the Kids' Inpatient Database	infants and children younger than 2 years vaccination status: unvaccinated country: United States setting: hospital, administrative data period: 2000, 2003, 2006 and 2009 n: 607 937 admissions NeonateInfant <1y1-4y	9.0 deaths per 10 000 RSV-associated admissions per 10 000 RSV-associated hospital admissions	surveillance	Byington et al. 2015 Pediatrics quote RESULTS: The KID data sets identified 607 937 RSV-associated admissions and 550 deaths (9.0 deaths/10 000 admissions). abstract, RESULTS Denominator is admissions, not infants. Most deaths were in children with complex chronic conditions; the authors call RSV deaths uncommon in the twenty-first century in the US. A different children's-hospital database in the same abstract gives a rate nearly three times higher.
RSV-attributable deaths (all settings) in children aged 0-60 months, global severity: death case definition: RSV-associated acute lower respiratory infection with laboratory confirmation; overall mortality modelled from community and hospital data	children aged 0-60 months vaccination status: unvaccinated country: global (481 studies) setting: community and hospital period: 2019 NeonateInfant <1y1-4y	101 400 (84 500–125 200) annual number of RSV-attributable deaths per year, global population aged 0-60 months	modelling	Li et al. 2022 Lancet quote We estimated that globally in 2019, there were 33·0 million RSV-associated acute lower respiratory infection episodes (uncertainty range [UR] 25·4-44·6 million), 3·6 million RSV-associated acute lower respiratory infection hospital admissions (2·9-4·6 million), 26 300 RSV-associated acute lower respiratory infection in-hospital deaths (15 100-49 100), and 101 400 RSV-attributable overall deaths (84 500-125 200) in children aged 0-60 months. abstract, FINDINGS The interval is the authors' uncertainty range, not a confidence interval. Pre-dates maternal vaccine and nirsevimab programmes, so this is a pre-intervention baseline. The same sentence also gives global hospital admissions and in-hospital deaths; the review estimates roughly three community deaths for every in-hospital death.
Share of all deaths attributable to RSV, children aged 28 days to 6 months severity: death case definition: RSV-attributable mortality fraction from modelled community and hospital mortality data	children aged 28 days to 6 months vaccination status: unvaccinated country: global period: 2019 NeonateInfant <1y	3.6 (3.0–4.4) proportion of all-cause deaths attributable to RSV (%) per all-cause death in the age group	modelling	Li et al. 2022 Lancet quote 2·0% of deaths in children aged 0-60 months (UR 1·6-2·4) and 3·6% of deaths in children aged 28 days to 6 months (3·0-4·4) were attributable to RSV. abstract, FINDINGS Uncertainty range, not a confidence interval. The authors phrase this as about one in every twenty-eight deaths at this age. The under-five figure in the same sentence is the next record.
Share of all deaths attributable to RSV, children aged 0-60 months severity: death case definition: RSV-attributable mortality fraction from modelled community and hospital mortality data	children aged 0-60 months vaccination status: unvaccinated country: global period: 2019 NeonateInfant <1y1-4y	2.0 (1.6–2.4) proportion of all-cause deaths attributable to RSV (%) per all-cause death in the age group	modelling	Li et al. 2022 Lancet quote 2·0% of deaths in children aged 0-60 months (UR 1·6-2·4) and 3·6% of deaths in children aged 28 days to 6 months (3·0-4·4) were attributable to RSV. abstract, FINDINGS Uncertainty range, not a confidence interval. One in every fifty deaths under five, per the authors' interpretation.
Share of global RSV-attributable child deaths occurring in low- and middle-income countries severity: death case definition: RSV-attributable deaths across all age bands under 5 years	children aged 0-60 months vaccination status: unvaccinated country: low-income and middle-income countries period: 2019 NeonateInfant <1y1-4y	more than 97 proportion of global RSV-attributable deaths occurring in LMICs (%) per global RSV-attributable death under 5 years	modelling	Li et al. 2022 Lancet quote More than 95% of RSV-associated acute lower respiratory infection episodes and more than 97% of RSV-attributable deaths across all age bands were in low-income and middle-income countries (LMICs). abstract, FINDINGS The same sentence puts more than 95% of RSV-ALRI episodes in LMICs. This is why global mortality figures must not be read as the risk faced by an infant in a high-income country; see the US case-fatality records.
RSV-ALRI in-hospital deaths in children under 5 years, global severity: death case definition: Laboratory-confirmed RSV acute lower respiratory infection admitted to hospital	children younger than 5 years vaccination status: unvaccinated country: global setting: hospital period: 2015 NeonateInfant <1y1-4y	59 600 (48 000–74 500) annual number of in-hospital deaths per year, global population under 5	modelling	Shi et al. 2017 Lancet quote FINDINGS: We estimated that globally in 2015, 33·1 million (uncertainty range [UR] 21·6-50·3) episodes of RSV-ALRI, resulted in about 3·2 million (2·7-3·8) hospital admissions, and 59 600 (48 000-74 500) in-hospital deaths in children younger than 5 years. abstract, FINDINGS Uncertainty range, not a confidence interval. Earlier edition of the Li estimate in the first record above; the later update revised in-hospital deaths downward and added community deaths. The same sentence gives global episodes and admissions.
Share of under-5 RSV-ALRI admissions and in-hospital deaths occurring under 6 months of age severity: hospitalisation and death case definition: RSV-ALRI hospital admissions and in-hospital deaths	children younger than 6 months as a share of under-5s vaccination status: unvaccinated country: global setting: hospital period: 2015 NeonateInfant <1y	45 proportion of under-5 RSV-ALRI admissions and in-hospital deaths (%) per under-5 RSV-ALRI admission or in-hospital death	modelling	Shi et al. 2017 Lancet quote About 45% of hospital admissions and in-hospital deaths due to RSV-ALRI occur in children younger than 6 months. abstract, INTERPRETATION This concentration in the first six months is the rationale for maternal vaccination and birth-season monoclonal antibody, which protect that window only.
Peak age of RSV infection incidence in LMIC preschool children severity: any infection case definition: RSV cases from community-based studies in the systematic review, fitted with generalised additive mixed models	children under 5 years in low- and middle-income countries vaccination status: unvaccinated country: low- and middle-income countries setting: community NeonateInfant <1y1-4y	4.8 peak age of RSV incidence (months)	modelling	Antillón et al. 2023 PLoS Med quote The peak age of community-based incidence is 4.8 months, and the mean and median age of infection is 18.9 and 14.7 months, respectively. abstract, METHODS AND FINDINGS Hospital-based data give a younger peak in the same abstract. Mean and median ages of infection are well over a year, so a product protecting only the first six months covers the peak but not most infections.
Share of under-5 RSV deaths in children under 6 months, LMICs severity: death case definition: RSV-associated deaths in LMIC studies	children under 6 months as a share of under-5s vaccination status: unvaccinated country: low- and middle-income countries NeonateInfant <1y	38 to 50 proportion of under-5 RSV deaths occurring under 6 months of age (%) per under-5 RSV death	modelling	Antillón et al. 2023 PLoS Med quote Children under 6 months of age constitute 10% of the population under 5 years of age but bear 20% to 29% of cases, 28% to 39% of hospitalizations, and 38% to 50% of deaths. abstract, METHODS AND FINDINGS A range from two model specifications, not a confidence interval. The same sentence notes under-6-month-olds are 10% of the under-5 population, so their share of deaths is four to five times their population share.
Median age at RSV-related in-hospital death, low-income and lower-middle-income countries severity: death case definition: Children under 5 years who died in hospital with community-acquired RSV infection	children younger than 5 years who died; median 5.0 months in LMICs vaccination status: not reported country: low-income and lower middle-income countries (within a 23-country series) setting: hospital period: 1995-2015 n: 358 deaths overall NeonateInfant <1y1-4y	5.0 median age at death (months)	case series	Scheltema et al. 2017 Lancet Glob Health quote Median age for RSV-related deaths was 5·0 months (IQR 2·3-11·0) in low-income or lower middle-income countries, 4·0 years (2·0-10·0) in upper middle-income countries, and 7·0 years (3·6-16·8) in high-income countries. abstract, FINDINGS Contrast with 7.0 years in high-income countries in the same sentence, where most deaths had comorbidities. A case series of deaths, not a rate; it says who dies, not how often.

Vaccine efficacy and effectiveness

Every estimate compiled, annotated by population (P), intervention (I), comparator (C), outcome (O) and study design (S).

Outcome (O)	Population (P)	Intervention / comparator	Estimate	Design (S)	Source
RSV-associated lower respiratory tract infection hospitalisation, infants from birth to 6 months, pooled real-world severity: hospitalisation case definition: RSV-associated LRTI hospitalisation in non-randomised studies, mothers vaccinated 14 or more days before delivery	infants from birth to 6 months pregnancy: mothers vaccinated 14 or more days before delivery country: Argentina, United Kingdom and United States period: January 2024 to April 2025 n: 3008 participants in 6 studies NeonateInfant <1y	RSVpreF bivalent (Abrysvo), given in pregnancy platform: recombinant protein subunit, unadjuvanted doses: 1 maternal dose time since vaccination: infant age 0-6 months vs infants born to unvaccinated mothers	78 (70–84) VE (%) = (1 - OR) x 100 follow-up: birth to 6 months	meta-analysis 6 observational studies	Batool et al. 2026 JAMA Pediatr quote Pooled vaccine effectiveness against RSV-associated LRTI hospitalization was 82% (95% CI, 81%-82%; 3 studies, 4397 participants; I2 = 0%) in infants from birth to 3 months and 78% (95% CI, 70%-84%; 6 studies, 3008 participants; I2 = 18.7%) in infants from birth to 6 months, when mothers were vaccinated 14 days or more before delivery. abstract, RESULTS Pooled with Hartung-Knapp adjustment; I2 18.7%. The birth-to-3-month pooled figure in the same sentence is 82% (81-82) from 3 studies. Observational, so maternal health-seeking behaviour is a confounder in every included study.
RSV-related hospitalisation, infants 0-12 months, pooled real-world programmes severity: hospitalisation case definition: RSV-related hospital admission in observational studies of all-infant nirsevimab programmes	infants aged 0-12 months country: France, Italy, Luxembourg, Spain, United States period: 2023-2025 NeonateInfant <1y	nirsevimab (Beyfortus) platform: monoclonal antibody doses: 1 time since vaccination: first season vs infants not receiving nirsevimab	0.17 (0.12–0.23) OR, nirsevimab vs no nirsevimab	meta-analysis 27 cohort and case-control studies	Sumsuzzman et al. 2025 Lancet Child Adolesc Health quote Nirsevimab was associated with a lower odds of RSV-related hospitalisation (odds ratio 0·17; 95% CI 0·12-0·23; I2=85·8%), a lower odds of ICU admission (0·19; 0·12-0·29; 55·6%), and a lower odds of LRTI incidence (0·25; 0·19-0·33; 35·1%) in infants aged 0-12 months. abstract, FINDINGS I2 85.8%, so heterogeneity is high. ICU admission OR 0.19 (0.12-0.29) in the same sentence. Length of stay did not differ between groups.
RSV-related hospital admission, pooled real-world nirsevimab studies severity: hospitalisation case definition: RSV-related hospital admissions in post-licensure studies	infants in first RSV season country: multiple period: studies published December 2022 to March 2025 NeonateInfant <1y	nirsevimab (Beyfortus) platform: monoclonal antibody doses: 1 time since vaccination: first season vs infants not receiving nirsevimab	80.7 (76.1–85.2) effectiveness (%)	meta-analysis 17 studies	Lee et al. 2025 Thorax quote Nirsevimab showed 80.7% effectiveness (95% CI: 75.7% to 85.7%; seven studies) against RSV-related emergency department visits, 80.7% (95% CI: 76.1% to 85.2%; 17 studies) against hospital admissions and 75.6% (95% CI: 63.3% to 87.9%; eight studies) against intensive care unit admissions. abstract, RESULTS Living systematic review. ICU admissions in the same abstract: 75.6% (63.3-87.9). The review found no effectiveness data yet for the maternal vaccine at its cutoff; see the maternal records above for later studies.
Medically attended severe RSV-associated lower respiratory tract illness in infants within 90 days of birth severity: severe lower respiratory tract illness case definition: Medically attended severe RSV-LRTI, primary endpoint, interim analysis	infants from birth to 90 days pregnancy: mothers vaccinated at 24 through 36 weeks of gestation country: 18 countries period: 2020-2022 n: 3570 infants (vaccine) and 3558 (placebo) NeonateInfant <1y	RSVpreF bivalent (Abrysvo), 120 ug, given in pregnancy platform: recombinant protein subunit, unadjuvanted doses: 1 maternal dose schedule: single dose at 24-36 weeks gestation (licensed window later narrowed to 32-36 weeks) time since vaccination: infant age 0-90 days vs placebo in pregnancy	81.8 (40.6–96.3) VE (%) follow-up: 90 days after birth	RCT	Kampmann et al. 2023 N Engl J Med quote Medically attended severe lower respiratory tract illness occurred within 90 days after birth in 6 infants of women in the vaccine group and 33 infants of women in the placebo group (vaccine efficacy, 81.8%; 99.5% CI, 40.6 to 96.3); 19 cases and 62 cases, respectively, occurred within 180 days after birth (vaccine efficacy, 69.4%; 97.58% CI, 44.3 to 84.1). abstract, RESULTS 99.5% CI because of alpha-spending at the interim analysis. Six vs 33 cases. The trial dosing window is wider than the licensed window; see the preterm-birth safety record.
Medically attended severe RSV-associated lower respiratory tract illness in infants within 180 days of birth severity: severe lower respiratory tract illness case definition: Medically attended severe RSV-LRTI, primary endpoint	infants from birth to 180 days pregnancy: mothers vaccinated at 24 through 36 weeks of gestation country: 18 countries period: 2020-2022 n: 3570 infants (vaccine) and 3558 (placebo) NeonateInfant <1y	RSVpreF bivalent (Abrysvo), given in pregnancy platform: recombinant protein subunit, unadjuvanted doses: 1 maternal dose time since vaccination: infant age 0-180 days vs placebo in pregnancy	69.4 (44.3–84.1) VE (%) follow-up: 180 days after birth	RCT	Kampmann et al. 2023 N Engl J Med quote Medically attended severe lower respiratory tract illness occurred within 90 days after birth in 6 infants of women in the vaccine group and 33 infants of women in the placebo group (vaccine efficacy, 81.8%; 99.5% CI, 40.6 to 96.3); 19 cases and 62 cases, respectively, occurred within 180 days after birth (vaccine efficacy, 69.4%; 97.58% CI, 44.3 to 84.1). abstract, RESULTS 97.58% CI. Lower than the 90-day figure as transferred maternal antibody wanes; 19 vs 62 cases.
Medically attended RSV-associated lower respiratory tract illness (any severity) in infants within 90 days of birth severity: lower respiratory tract illness, any severity case definition: Medically attended RSV-LRTI, second primary endpoint	infants from birth to 90 days pregnancy: mothers vaccinated at 24 through 36 weeks of gestation country: 18 countries period: 2020-2022 NeonateInfant <1y	RSVpreF bivalent (Abrysvo), given in pregnancy platform: recombinant protein subunit, unadjuvanted doses: 1 maternal dose time since vaccination: infant age 0-90 days vs placebo in pregnancy	57.1 (14.7–79.8) VE (%) follow-up: 90 days after birth	RCT	Kampmann et al. 2023 N Engl J Med quote Medically attended RSV-associated lower respiratory tract illness occurred within 90 days after birth in 24 infants of women in the vaccine group and 56 infants of women in the placebo group (vaccine efficacy, 57.1%; 99.5% CI, 14.7 to 79.8); these results did not meet the statistical success criterion. abstract, RESULTS This endpoint did not meet the prespecified statistical success criterion (lower bound above twenty percent). Efficacy against any medically attended LRTI is lower than against severe LRTI.
Severe RSV-associated medically attended lower respiratory tract illness in infants within 90 days of birth, final analysis severity: severe lower respiratory tract illness case definition: Newborn and infant severe RSV-associated medically attended LRTI, final analysis	infants from birth to 90 days pregnancy: mothers vaccinated at 24-36 weeks of gestation country: 18 countries period: 2020-2023 n: 7,307 children born NeonateInfant <1y	RSVpreF bivalent (Abrysvo), given in pregnancy platform: recombinant protein subunit, unadjuvanted doses: 1 maternal dose time since vaccination: infant age 0-90 days vs placebo in pregnancy	82.4 (57.5–93.9) VE (%) follow-up: 90 days after birth	RCT	Simões et al. 2025 Obstet Gynecol quote Vaccine efficacy , defined as protection against newborn and infant severe RSV-associated medically attended lower respiratory tract illness, was 82.4% (95% CI, 57.5-93.9) and 70.0% (95% CI, 50.6-82.5) within 90 and 180 days of birth, respectively. abstract, RESULTS Final analysis of MATISSE with 95% CIs; consistent with the interim. The 180-day figure in the same sentence (70.0, 50.6-82.5) is the next record.
Severe RSV-associated medically attended lower respiratory tract illness in infants within 180 days of birth, final analysis severity: severe lower respiratory tract illness case definition: Newborn and infant severe RSV-associated medically attended LRTI, final analysis	infants from birth to 180 days pregnancy: mothers vaccinated at 24-36 weeks of gestation country: 18 countries period: 2020-2023 n: 7,307 children born NeonateInfant <1y	RSVpreF bivalent (Abrysvo), given in pregnancy platform: recombinant protein subunit, unadjuvanted doses: 1 maternal dose time since vaccination: infant age 0-180 days vs placebo in pregnancy	70.0 (50.6–82.5) VE (%) follow-up: 180 days after birth	RCT	Simões et al. 2025 Obstet Gynecol quote Vaccine efficacy , defined as protection against newborn and infant severe RSV-associated medically attended lower respiratory tract illness, was 82.4% (95% CI, 57.5-93.9) and 70.0% (95% CI, 50.6-82.5) within 90 and 180 days of birth, respectively. abstract, RESULTS
Medically attended RSV-associated lower respiratory tract infection through 150 days severity: medically attended lower respiratory tract infection case definition: Medically attended RSV-LRTI through 150 days after injection, primary endpoint	healthy infants born at 35 weeks gestation or later, entering first RSV season country: multinational period: 2019-2021 n: 1490 infants NeonateInfant <1y	nirsevimab (Beyfortus) platform: monoclonal antibody doses: 1 time since vaccination: through 150 days after injection vs placebo	74.5 (49.6–87.1) efficacy (%) follow-up: 150 days	RCT	Hammitt et al. 2022 N Engl J Med quote Medically attended RSV-associated lower respiratory tract infection occurred in 12 infants (1.2%) in the nirsevimab group and in 25 infants (5.0%) in the placebo group; these findings correspond to an efficacy of 74.5% (95% confidence interval [CI], 49.6 to 87.1; P<0.001) for nirsevimab. abstract, RESULTS Nirsevimab is passive immunisation (a monoclonal antibody), not a vaccine; included because it is the alternative to maternal vaccination for the same infants. 12 (1.2%) vs 25 (5.0%) cases.
Hospitalisation for RSV-associated lower respiratory tract infection through 150 days severity: hospitalisation case definition: Hospitalisation for RSV-LRTI, secondary endpoint	healthy infants born at 35 weeks gestation or later country: multinational period: 2019-2021 n: 1490 infants NeonateInfant <1y	nirsevimab (Beyfortus) platform: monoclonal antibody doses: 1 time since vaccination: through 150 days after injection vs placebo	62.1 (-8.6–86.8) efficacy (%) follow-up: 150 days	RCT	Hammitt et al. 2022 N Engl J Med quote Hospitalization for RSV-associated lower respiratory tract infection occurred in 6 infants (0.6%) in the nirsevimab group and in 8 infants (1.6%) in the placebo group (efficacy, 62.1%; 95% CI, -8.6 to 86.8; P = 0.07). abstract, RESULTS Not statistically significant in MELODY alone (6 vs 8 hospitalisations, P = 0.07); the pooled analysis and HARMONIE below settle the hospitalisation question.
Hospital admission for medically attended RSV lower respiratory tract infection, pooled phase 2b and MELODY severity: hospitalisation case definition: Hospital admission for medically attended RSV LRTI through 150 days, weight-banded dosing	infants born at 29 weeks gestation to term, first RSV season country: multinational n: 2350 infants NeonateInfant <1y	nirsevimab (Beyfortus), 50 mg under 5 kg or 100 mg at 5 kg or more platform: monoclonal antibody doses: 1 time since vaccination: through 150 days vs placebo	77.3 (50.3–89.7) relative risk reduction (%) follow-up: 150 days	RCT phase 2b trial and MELODY	Simões et al. 2023 Lancet Child Adolesc Health quote Consistent efficacy was shown for additional endpoints of RSV LRTI hospital admission (nine [1%] nirsevimab recipients vs 21 [3%] placebo recipients; 77·3% [50·3-89·7]) and very severe RSV (five [<1%] vs 18 [2%]; 86·0% [62·5-94·8]). abstract, FINDINGS Very severe RSV LRTI in the same sentence: 86.0% (62.5-94.8). Efficacy in chronic lung disease, congenital heart disease and extreme prematurity is extrapolated from pharmacokinetics, not measured.
Hospitalisation for RSV-associated lower respiratory tract infection, pragmatic trial severity: hospitalisation case definition: Hospital admission with an RSV-positive test, through the RSV season	infants 12 months or younger born at 29 weeks gestation or later, first RSV season country: France, Germany, United Kingdom period: 2022-2023 season n: 8058 infants NeonateInfant <1y	nirsevimab (Beyfortus) platform: monoclonal antibody doses: 1 time since vaccination: through the RSV season vs standard care (no intervention), open-label	83.2 (67.8–92.0) efficacy (%)	RCT	Drysdale et al. 2023 N Engl J Med quote Eleven infants (0.3%) in the nirsevimab group and 60 (1.5%) in the standard-care group were hospitalized for RSV-associated lower respiratory tract infection, which corresponded to a nirsevimab efficacy of 83.2% (95% confidence interval [CI], 67.8 to 92.0; P<0.001). abstract, RESULTS HARMONIE. Open-label pragmatic design, so care-seeking could differ by arm; eleven versus sixty hospitalisations. Country estimates were lowest in Germany and highest in France.
Very severe RSV-associated lower respiratory tract infection severity: very severe LRTI case definition: Hospitalisation for RSV-LRTI with oxygen saturation below 90% and need for supplemental oxygen	infants 12 months or younger, first RSV season country: France, Germany, United Kingdom period: 2022-2023 season n: 8058 infants NeonateInfant <1y	nirsevimab (Beyfortus) platform: monoclonal antibody doses: 1 time since vaccination: through the RSV season vs standard care (no intervention)	75.7 (32.8–92.9) efficacy (%)	RCT	Drysdale et al. 2023 N Engl J Med quote Very severe RSV-associated lower respiratory tract infection occurred in 5 infants (0.1%) in the nirsevimab group and in 19 (0.5%) in the standard-care group, which represented a nirsevimab efficacy of 75.7% (95% CI, 32.8 to 92.9; P = 0.004). abstract, RESULTS 5 vs 19 cases.
Hospitalisation for RSV-associated lower respiratory tract infection through 180 days severity: hospitalisation case definition: Hospitalisation for RSV-LRTI up to 180 days after dosing or randomisation	infants 12 months or younger, median 4.0 months at randomisation country: France, Germany, United Kingdom period: August 2022 to 2023 n: 8057 infants NeonateInfant <1y	nirsevimab (Beyfortus), 50 mg under 5 kg or 100 mg at 5 kg or more platform: monoclonal antibody doses: 1 time since vaccination: through 180 days after dosing vs standard care (no intervention)	82.7 (67.8–91.5) efficacy (%) follow-up: 180 days	RCT	Munro et al. 2025 Lancet Child Adolesc Health quote Up to 180 days, 12 (0·3%) of 4038 infants in the nirsevimab group and 68 (1·7%) of 4019 infants in the standard care group had been hospitalised for RSV-associated lower respiratory tract infection, corresponding to a nirsevimab efficacy of 82·7% (95% CI 67·8-91·5; p<0·0001). abstract, FINDINGS Protection held through six months, exceeding the typical five-month season; 12 vs 68 hospitalisations.
RSV-associated lower respiratory tract disease leading to hospitalisation, infants to 3 months severity: hospitalisation case definition: Infants 6 months or younger hospitalised with LRTD and tested for RSV by PCR or immunofluorescence; mothers vaccinated at 32-36 weeks and 14 or more days before delivery	infants from birth to 3 months pregnancy: mothers vaccinated at 32+0 to 36+6 weeks of gestation country: Argentina setting: 12 hospitals period: April-September 2024 n: 505 infants (286 cases, 219 controls) NeonateInfant <1y	RSVpreF bivalent (Abrysvo), given in pregnancy platform: recombinant protein subunit, unadjuvanted doses: 1 maternal dose time since vaccination: infant age 0-3 months vs test-negative controls (infants born to unvaccinated mothers)	78.6 (62.1–87.9) VE (%) follow-up: birth to 3 months	test-negative	Pérez et al. 2025 Lancet Infect Dis quote Vaccine effectiveness against RSV-associated LRTD leading to infant hospitalisation was 78·6% (95% CI 62·1-87·9) from birth to age 3 months and 71·3% (53·3-82·3) from birth to age 6 months. abstract, FINDINGS First national maternal programme, first season. Three RSV in-hospital deaths occurred, all in infants of unvaccinated mothers. Pfizer-funded.
RSV-associated lower respiratory tract disease leading to hospitalisation, infants to 6 months severity: hospitalisation case definition: As above, birth to 6 months	infants from birth to 6 months pregnancy: mothers vaccinated at 32+0 to 36+6 weeks of gestation country: Argentina setting: 12 hospitals period: April-September 2024 NeonateInfant <1y	RSVpreF bivalent (Abrysvo), given in pregnancy platform: recombinant protein subunit, unadjuvanted doses: 1 maternal dose time since vaccination: infant age 0-6 months vs test-negative controls	71.3 (53.3–82.3) VE (%) follow-up: birth to 6 months	test-negative	Pérez et al. 2025 Lancet Infect Dis quote Vaccine effectiveness against RSV-associated LRTD leading to infant hospitalisation was 78·6% (95% CI 62·1-87·9) from birth to age 3 months and 71·3% (53·3-82·3) from birth to age 6 months. abstract, FINDINGS Severe LRTD hospitalisation to six months in the same abstract was similar.
RSV-related lower respiratory tract infection hospital admission, infants aged 90 days or younger severity: hospitalisation case definition: RSV-positive PCR within 14 days before or 2 days after admission for LRTI, national linked data; vaccinated more than 14 days before delivery	infants aged 90 days or younger pregnancy: mothers offered vaccine from 28 weeks of gestation country: Scotland setting: national population-based period: August 2024 to March 2025 n: 354 cases, 3511 matched controls, from 27 565 livebirths NeonateInfant <1y	RSVpreF bivalent (Abrysvo), given in pregnancy platform: recombinant protein subunit, unadjuvanted doses: 1 maternal dose time since vaccination: infant age 0-90 days vs infants of unvaccinated mothers, matched on week of birth and gestational age	82.2 (75.1–87.3) VE (%) follow-up: birth to 90 days	case-control	McLachlan et al. 2026 Lancet Infect Dis quote Adjusted vaccine effectiveness against RSV-associated LRTI hospital admission was 82·2% (95% CI 75·1-87·3; p<0·0001) in vaccinated infants compared with unvaccinated infants, which translated to 219 (95% CI 189-243) RSV-related LRTI hospital admissions averted during the study period. abstract, FINDINGS Unfunded national study. A cohort sensitivity analysis gave a near-identical estimate. Uptake was about half, so confounding by maternal health behaviour was possible; models adjusted for deprivation, smoking, parity, ethnicity and maternal age.
RSV-related lower respiratory tract infection hospital admission, preterm infants aged 90 days or younger severity: hospitalisation case definition: As above, restricted to infants born before 37 weeks	infants aged 90 days or younger born preterm risk group: preterm birth pregnancy: mothers vaccinated more than 14 days before delivery country: Scotland period: August 2024 to March 2025 NeonateInfant <1y	RSVpreF bivalent (Abrysvo), given in pregnancy platform: recombinant protein subunit, unadjuvanted doses: 1 maternal dose time since vaccination: infant age 0-90 days vs preterm infants of unvaccinated mothers	89.9 (55.3–97.7) VE (%) follow-up: birth to 90 days	case-control	McLachlan et al. 2026 Lancet Infect Dis quote Adjusted vaccine effectiveness remained high among infants born preterm (<37 weeks' gestation; 89·9% [55·3-97·7]; p=0·0025), as well as for term-born infants (≥37 weeks' gestation; 81·5% [73·9-87·0]; p<0·0001). abstract, FINDINGS Term infants in the same sentence: 81.5% (73.9-87.0). Preterm infants whose mothers are vaccinated close to delivery may transfer less antibody, so the window matters.
Hospitalisation for RSV-associated acute lower respiratory infection in infants, mothers vaccinated more than 14 days before delivery severity: hospitalisation case definition: Infants with ALRI admitted to 30 UK hospitals and tested for RSV	infants, median 1.6 months pregnancy: mothers eligible from 28 weeks of gestation, vaccinated more than 14 days before delivery country: United Kingdom (England and Scotland) setting: 30 hospital sites period: September 2024 to January 2025 n: 537 mother-infant pairs NeonateInfant <1y	RSVpreF bivalent (Abrysvo), given in pregnancy platform: recombinant protein subunit, unadjuvanted doses: 1 maternal dose time since vaccination: first months of life, first programme season vs test-negative controls	72 (48–85) VE (%)	test-negative	Williams et al. 2025 Lancet Child Adolesc Health quote The adjusted effectiveness of maternal RSVpreF vaccination for preventing infant hospitalisation was 58% (95% CI 28-75) for infants whose mothers were vaccinated at any time before delivery and 72% (48-85) for infants whose mothers were vaccinated more than 14 days before delivery (39 [11%] of 357 RSV-positive cases vs 43 [33%] of 129 RSV-negative controls). abstract, FINDINGS Effectiveness for mothers vaccinated at any time before delivery was 58% (28-75) in the same sentence, showing that doses given within two weeks of birth add little.
Hospital admission with RSV-associated acute lower respiratory tract infection, infants up to 6 months severity: hospitalisation case definition: Prospectively enrolled infants 6 months or younger admitted with ALRI and tested for RSV, excluding nirsevimab recipients	infants aged 6 months or younger pregnancy: mothers vaccinated from 28 weeks of gestation in a year-round programme country: United Kingdom setting: 37 hospital sites period: September 2025 to January 2026 n: 694 infants (429 cases, 265 controls) NeonateInfant <1y	RSVpreF bivalent (Abrysvo), given in pregnancy platform: recombinant protein subunit, unadjuvanted doses: 1 maternal dose time since vaccination: infant age 0-6 months vs test-negative controls	61 (38–75) VE (%) follow-up: birth to 6 months	test-negative	O'Hagan et al. 2026 Lancet Child Adolesc Health quote The adjusted vaccine effectiveness of maternal RSVpreF vaccination for preventing infant hospital admission was 61% (95% CI 38-75) for infants aged up to 6 months, and 76% (54-87) for infants aged up to 3 months. abstract, FINDINGS Second programme year in steady state. Effectiveness to 3 months in the same sentence was 76% (54-87), so protection fades across the first half-year as in the trial.

Vaccine safety and adverse events

Harms measured after vaccination against an unvaccinated or baseline comparator. Kept separate from post-acute sequelae, which follow the disease, not the vaccine.

Outcome (O)	Population (P)	Intervention / comparator	Estimate	Design (S)	Source
Preterm birth (before 37 weeks) after maternal RSVpreF vaccination, trial dosing interval 24-36 weeks severity: preterm birth case definition: Preterm birth in the pooled phase 2b and phase 3 trials, trial dosing interval	pregnant women aged 49 or younger vaccinated at 24-36 weeks; outcome in their infants pregnancy: vaccinated at 24-36 weeks of gestation country: 18 countries period: 2020-2022 FetusNeonate	RSVpreF bivalent (Abrysvo), given in pregnancy platform: recombinant protein subunit, unadjuvanted doses: 1 maternal dose vs placebo in pregnancy	1.20 (0.99–1.46) relative risk	RCT	cdc.gov quote Effect estimates for the Pfizer maternal RSVpreF vaccine for the trial dosing interval and the approved dosing interval Outcome \| VE or RR (CI)* \| Trial dosing interval (24–36 weeks’ gestation) † \| Approved dosing interval (32–36 weeks’ gestation) § \| Benefits (efficacy against outcome), (VE) assessed at age 0–180 days \| Medically attended RSV-associated LRTI in infants \| 51.3 (29.4 to 66.8) ¶ \| 57.3 (29.8 to 74.7) \| Severe medically attended RSV-associated LRTI in infants \| 69.4 (44.3 to 84.1) ¶ \| 76.5 (41.3 to 92.1) \| Hospitalization for RSV-associated LRTI \| 56.8 (10.1 to 80.7) †† \| 48.2 (–22.9 to 79.6) \| Intensive care unit admission from RSV hospitalization in infants \| 42.9 (–124.8 to 87.7) \| One event in the vaccine group Two events in the placebo group \| Mechanical ventilation from RSV hospitalization in infants \| 100 (–9.1 to 100) \| Zero events in the vaccine group Two events in the placebo group \| All-cause medically attended LRTI in infants \| 2.5 (–17.9 to 19.4) †† \| 7.3 (–15.7 to 25.7) \| All-cause hospitalization for LRTI in infants \| 28.9 (–2.0 to 50.8) \| 34.7 (–18.8 to 64.9) \| Harms (RR) §§ \| Serious adverse events in pregnant persons ¶¶ \| 1.06 (0.95 to 1.17) \| 1.02 (0.87 to 1.20) \| Reactogenicity (grade 3 or higher systemic reactions) in pregnant persons* \| 0.97 (0.72 to 1.31) \| 0.98 (0.62 to 1.54) \| Serious adverse events in infants ††† \| 1.01 (0.91 to 1.11) \| 1.04 (0.90 to 1.20) \| Preterm birth (<37 weeks’ gestational age) \| 1.20 (0.99 to 1.46) \| 1.15 (0.82 to 1.61) \| Abbreviations: GRADE = Grading of Recommendations, Assessments, Development, and Evaluations; LRTI = lower respiratory tract infection; RR = relative risk; RSV = respiratory syncytial virus; VE = vaccine efficacy. * 95% CI unless otherwise noted. Table 1 (GRADE summary), preterm birth row The second figure in the same table row, 1.15 (0.82-1.61), is for the approved 32-36 week dosing interval. Not statistically significant, but ACIP rated certainty very low for this critical harm and FDA restricted the licence to 32-36 weeks to avoid preterm birth before 32 weeks. Absolute preterm proportions for both windows are on the same page.

RSV disease in older adults Respiratory syncytial virus

Disease risks

Acute risks of the infection itself: complications, hospitalisation, ICU, death.

Outcome (O)	Population (P)	Comparator	Estimate	Design (S)	Source
Case fatality among older adults with RSV infection severity: death case definition: Symptomatic RSV infection in studies of adults aged 60 or older in developed countries, mostly hospital-based	adults aged 60 years or older vaccination status: unvaccinated country: developed countries setting: mixed, predominantly hospital period: studies published 2000-2019 n: 103 articles 50-64y65+		8.18 (5.54–11.94) pooled case fatality proportion (%) per RSV case in the included studies	meta-analysis	Nguyen-Van-Tam et al. 2022 Eur Respir Rev quote Among older adults, RSV caused 4.66% (95% CI 3.34-6.48%) of symptomatic respiratory infections in annual studies and 7.80% (95% CI 5.77-10.45%) in seasonal studies; RSV-related case fatality proportion (CFP) was 8.18% (95% CI 5.54-11.94%). abstract, RESULTS Pooled across heterogeneous study designs; the authors stress data paucity. Hospital-based ascertainment inflates case fatality relative to all infections. High-risk adults in the same abstract had a slightly higher pooled proportion.
Death within 1 year of admission, RSV vs influenza, hospitalised adults 60 or older severity: death case definition: Laboratory-confirmed RSV or influenza in hospitalised Kaiser Permanente members	adults aged 60 years or older (mean 78.5 years for RSV) vaccination status: not reported country: United States setting: hospital period: 2011-2015 n: 645 RSV and 1878 influenza patients 50-64y65+	vs hospitalised adults with influenza	1.3 (1.0–1.6) adjusted OR, RSV vs influenza per hospitalised patient	cohort	Ackerson et al. 2019 Clin Infect Dis quote In adjusted analyses, RSV infection was associated with greater odds of length of stay ≥7 days (odds ratio [OR] = 1.5; 95% confidence interval [CI], 1.2-1.8; P < .001); pneumonia (OR = 2.7; 95% CI, 2.2-3.2; P < .001); intensive care unit admission (OR = 1.3; 95% CI, 1.0-1.7; P = .023); exacerbation of COPD (OR = 1.7; 95% CI, 1.3-2.4; P = .001); and greater mortality within 1 year of admission (OR = 1.3; 95% CI, 1.0-1.6; P = .019). abstract, RESULTS Comparator is influenza, not uninfected adults; the figure says RSV is at least as lethal as influenza once a person is admitted. RSV patients were older with more heart failure and COPD at baseline, which the models adjusted for.
Pneumonia during admission, RSV vs influenza, hospitalised adults 60 or older severity: pneumonia case definition: Laboratory-confirmed RSV or influenza in hospitalised Kaiser Permanente members	adults aged 60 years or older vaccination status: not reported country: United States setting: hospital period: 2011-2015 n: 645 RSV and 1878 influenza patients 50-64y65+	vs hospitalised adults with influenza	2.7 (2.2–3.2) adjusted OR, RSV vs influenza per hospitalised patient	cohort	Ackerson et al. 2019 Clin Infect Dis quote In adjusted analyses, RSV infection was associated with greater odds of length of stay ≥7 days (odds ratio [OR] = 1.5; 95% confidence interval [CI], 1.2-1.8; P < .001); pneumonia (OR = 2.7; 95% CI, 2.2-3.2; P < .001); intensive care unit admission (OR = 1.3; 95% CI, 1.0-1.7; P = .023); exacerbation of COPD (OR = 1.7; 95% CI, 1.3-2.4; P = .001); and greater mortality within 1 year of admission (OR = 1.3; 95% CI, 1.0-1.6; P = .019). abstract, RESULTS ICU admission OR 1.3 (1.0-1.7) and length of stay 7 days or more OR 1.5 are in the same sentence.
20-day all-cause mortality, RSV vs seasonal influenza, hospitalised adults severity: death case definition: RSV by multiplex PCR in adults admitted for suspected viral infection, compared with adults hospitalised for seasonal influenza	adults 18 years or older; RSV patients older than influenza patients vaccination status: not reported country: South Korea setting: hospital, single university centre period: 2013-2015 n: 87 RSV and 312 influenza patients 18-49y50-64y65+	vs adults hospitalised with seasonal influenza	2.32 (1.17–4.58) adjusted HR for death vs influenza per hospitalised patient	cohort	Kwon et al. 2017 BMC Infect Dis quote RSV infection showed significantly higher risk of death compared to the seasonal influenza group, with hazard ratio, 2.32 (95% CI, 1.17-4.58). abstract, RESULTS Small single-centre study; crude twenty-day mortality was nearly three times higher for RSV than for influenza. Adjusted for comorbidities but residual confounding by age and frailty is likely.
RSV-associated hospitalisation, adults 75 years or older severity: hospitalisation case definition: Laboratory-confirmed RSV within 14 days before or during hospitalisation, RSV-NET population-based surveillance; rates not adjusted for undertesting	adults 75 years or older vaccination status: unvaccinated country: United States setting: hospital, population-based surveillance (12 states) period: 2022-2023 season 65+		244.7 (207.9–297.3) hospitalisation rate per 100 000 adults per season per 100 000 adults aged 75 or older	surveillance	Havers et al. 2024 JAMA Netw Open quote Rates were lowest among adults aged 18 to 49 years (8.6 [95% CI, 5.7-16.8] per 100 000 adults in 2016-2017 to 13.1 [95% CI, 11.0-16.1] per 100 000 adults in 2022-2023) and highest among adults 75 years or older (244.7 [95% CI, 207.9-297.3] per 100 000 adults in 2022-2023 to 411.4 [95% CI, 292.1-695.4] per 100 000 adults in 2017-2018). abstract, RESULTS Pre-vaccine baseline; the highest of all age groups. The same sentence gives the 2017-2018 peak season, which is the next record. Adjusted for undertesting the true burden is higher.
RSV-associated hospitalisation, adults 75 years or older, highest-burden season severity: hospitalisation case definition: Laboratory-confirmed RSV within 14 days before or during hospitalisation, RSV-NET population-based surveillance	adults 75 years or older vaccination status: unvaccinated country: United States setting: hospital, population-based surveillance period: 2017-2018 season 65+		411.4 (292.1–695.4) hospitalisation rate per 100 000 adults per season per 100 000 adults aged 75 or older	surveillance	Havers et al. 2024 JAMA Netw Open quote Rates were lowest among adults aged 18 to 49 years (8.6 [95% CI, 5.7-16.8] per 100 000 adults in 2016-2017 to 13.1 [95% CI, 11.0-16.1] per 100 000 adults in 2022-2023) and highest among adults 75 years or older (244.7 [95% CI, 207.9-297.3] per 100 000 adults in 2022-2023 to 411.4 [95% CI, 292.1-695.4] per 100 000 adults in 2017-2018). abstract, RESULTS Seasonal variation across the seven surveillance seasons is large; read with the 2022-2023 record above.
RSV-associated hospitalisation, adults aged 18-49 years severity: hospitalisation case definition: Laboratory-confirmed RSV within 14 days before or during hospitalisation, RSV-NET	adults aged 18 to 49 years vaccination status: unvaccinated country: United States setting: hospital, population-based surveillance period: 2016-2017 season 18-49y		8.6 (5.7–16.8) hospitalisation rate per 100 000 adults per season per 100 000 adults aged 18-49	surveillance	Havers et al. 2024 JAMA Netw Open quote Rates were lowest among adults aged 18 to 49 years (8.6 [95% CI, 5.7-16.8] per 100 000 adults in 2016-2017 to 13.1 [95% CI, 11.0-16.1] per 100 000 adults in 2022-2023) and highest among adults 75 years or older (244.7 [95% CI, 207.9-297.3] per 100 000 adults in 2022-2023 to 411.4 [95% CI, 292.1-695.4] per 100 000 adults in 2017-2018). abstract, RESULTS Included as the comparison that shows the roughly thirty- to fifty-fold age gradient to the 75-plus rate.
RSV-associated in-hospital deaths among US adults, annual estimate severity: death case definition: Extrapolated from RSV-NET after adjusting for test sensitivity and undertesting	adults 18 years or older vaccination status: unvaccinated country: United States setting: hospital period: 2018-2019 (low) to 2017-2018 (high) 18-49y50-64y65+		4680 to 8620 estimated annual in-hospital deaths per year, US adult population	surveillance	Havers et al. 2024 JAMA Netw Open quote Estimated annual in-hospital deaths ranged from 4680 (95% CI, 3570-6820) in 2018 to 2019 to 8620 (95% CI, 6220-14 090) in 2017 to 2018. abstract, RESULTS A range across seasons; the confidence interval for each end is in the same sentence. Adults seventy-five or older accounted for most in-hospital deaths (next record).
Share of adult RSV in-hospital deaths occurring in adults 75 or older severity: death case definition: Laboratory-confirmed RSV-associated hospitalisations in RSV-NET	adults 75 years or older as a share of all adults vaccination status: unvaccinated country: United States setting: hospital period: 2016-2017 to 2022-2023 65+		58.7 proportion of adult RSV in-hospital deaths (%) per adult RSV-associated in-hospital death	surveillance	Havers et al. 2024 JAMA Netw Open quote Adults 75 years or older accounted for 45.6% (range, 43.1%-48.8%) of all RSV-associated hospitalizations, 38.6% (range, 36.7%-41.0%) of all ICU admissions, and 58.7% (range, 51.9%-67.1%) of all in-hospital deaths. abstract, RESULTS The range is across seasons, not a CI. The same sentence gives 45.6% of hospitalisations and 38.6% of ICU admissions in this age group.
ICU admission among adults 50 or older hospitalised with RSV severity: ICU admission case definition: Laboratory-confirmed RSV detected through clinician-directed testing, RSV-NET medical record abstraction	adults aged 50 years or older, median 72.7 years vaccination status: unvaccinated country: United States setting: hospital period: 2014-2015 through 2017-2018 and 2022-2023 seasons n: 6248 hospitalised adults 50-64y65+		18.6 proportion of hospitalised RSV cases admitted to ICU (%) per RSV-associated hospitalisation	surveillance	Woodruff et al. 2024 JAMA Intern Med quote Among all hospitalized adults with RSV infection, 18.6% required ICU admission and 4.9% died during hospitalization. abstract, RESULTS Denominator is hospitalised cases, not the population. In-hospital death from the same sentence is the next record.
In-hospital death among adults 50 or older hospitalised with RSV severity: death case definition: Laboratory-confirmed RSV, RSV-NET medical record abstraction	adults aged 50 years or older, median 72.7 years vaccination status: unvaccinated country: United States setting: hospital period: 2014-2015 through 2017-2018 and 2022-2023 seasons n: 6248 hospitalised adults 50-64y65+		4.9 in-hospital case fatality (%) per RSV-associated hospitalisation	surveillance	Woodruff et al. 2024 JAMA Intern Med quote Among all hospitalized adults with RSV infection, 18.6% required ICU admission and 4.9% died during hospitalization. abstract, RESULTS Roughly one in twenty hospitalised older adults with RSV died in hospital before vaccines were available. Clinician-directed testing means milder admissions are under-ascertained, which inflates severity proportions.
Acute cardiac event during RSV hospitalisation, adults 50 or older severity: acute cardiac event (most often acute heart failure) case definition: Acute cardiac events identified by ICD discharge codes and discharge summary review	adults aged 50 years or older vaccination status: unvaccinated country: United States setting: hospital period: 2014-2015 through 2017-2018 and 2022-2023 seasons n: 6248 hospitalised adults 50-64y65+		22.4 (21.0–23.7) weighted prevalence of acute cardiac event per hospitalisation (%) per RSV-associated hospitalisation	surveillance	Woodruff et al. 2024 JAMA Intern Med quote The weighted estimated prevalence of experiencing a cardiac event was 22.4% (95% CI, 21.0%-23.7%). abstract, RESULTS Nearly one in four hospitalised older adults with RSV had an acute cardiac event; about one in twelve of those without known cardiovascular disease did. Those with a cardiac event had higher ICU admission and death risk.
RSV hospitalisation, adults 50 or older, compared with influenza severity: hospitalisation case definition: RT-PCR on nasal/throat swabs from residents admitted with acute respiratory illness, prospective enrolment	adults aged 50 years or older vaccination status: unvaccinated country: United States (Nashville, Tennessee) setting: hospital, population-based period: 3 consecutive winters n: 508 tested patients 50-64y65+		15.01 annual hospitalisation rate per 10 000 residents per 10 000 county residents aged 50 or older per year	surveillance	Widmer et al. 2012 J Infect Dis quote Over 3 years, average annual rates of hospitalization were 15.01, 9.82, and 11.81 per 10,000 county residents due to RSV, HMPV, and influenza, respectively. abstract, RESULTS Influenza in the same sentence was lower, in a population in which most of those sixty-five or older had influenza vaccination; RSV hospitalisation rate in this age group was similar to or above influenza.
RSV-associated all-cause deaths, United States, annual mean severity: death case definition: Deaths attributed to RSV circulation by age-specific Poisson regression on national mortality and viral surveillance data	all ages vaccination status: unvaccinated country: United States period: 1990-1991 through 1998-1999 seasons All ages		17 358 annual mean RSV-associated all-cause deaths per year, US population	modelling	Thompson et al. 2003 JAMA quote Influenza viruses and RSV, respectively, were associated with annual means (SD) of 8097 (3084) and 2707 (196) underlying pneumonia and influenza deaths, 36 155 (11 055) and 11 321 (668) underlying respiratory and circulatory deaths, and 51 203 (15 081) and 17 358 (1086) all-cause deaths. abstract, RESULTS The bracketed figure is a standard deviation across seasons, not a CI. Statistically attributed deaths, not laboratory-confirmed. Influenza averaged three times as many deaths in the same model. Most RSV respiratory and circulatory deaths were in people aged sixty-five or older (next record).
Share of RSV-associated respiratory and circulatory deaths in people 65 or older severity: death case definition: Modelled RSV-associated deaths with underlying respiratory and circulatory causes	persons aged 65 years or older as a share of all ages vaccination status: unvaccinated country: United States period: 1990-1991 through 1998-1999 seasons 65+		78 proportion of RSV-associated respiratory and circulatory deaths (%) per RSV-associated respiratory and circulatory death	modelling	Thompson et al. 2003 JAMA quote For underlying respiratory and circulatory deaths, 90% of influenza- and 78% of RSV-associated deaths occurred among persons aged 65 years or older. abstract, RESULTS Pre-vaccine era. Influenza was associated with more deaths than RSV in all age groups except children under 1 year, per the same abstract.

Post-acute and long-term sequelae

What can follow the acute illness: chronic disease, disability, cancers, congenital syndromes, post-infectious conditions.

Outcome (O)	Population (P)	Comparator	Estimate	Design (S)	Source
Guillain-Barre syndrome within 42 days after medically attended RSV disease, adults 65 or older severity: Guillain-Barre syndrome case definition: Incident inpatient GBS by ICD codes 1-42 days after RSV disease index date, Medicare claims	adults aged 65 years or older prior infection: medically attended RSV disease vaccination status: not reported country: United States setting: Medicare claims period: 2011-2024 n: 452 471 patients with RSV disease 65+	vs the same individuals' control periods (-180 to -22 days and 43 to 180 days from RSV index date)	2.11 (1.01–4.37) incidence rate ratio, risk window vs control window follow-up: 1 to 42 days after RSV disease	SCCS	Liang et al. 2026 Clin Infect Dis quote The adjusted IRR for GBS after RSV disease was 2.11 (95% confidence interval, 1.01-4.37), consistent across sensitivity analyses of alternative risk/control periods and after excluding coinfections. abstract, RESULTS Fewer than eleven GBS cases in the risk window, so the lower bound sits just above 1. Self-controlled design removes fixed confounders but not time-varying ones such as co-infection; the estimate held after excluding co-infections. Placed here so the vaccine GBS safety records can be read against the disease's own GBS risk.

Vaccine efficacy and effectiveness

Every estimate compiled, annotated by population (P), intervention (I), comparator (C), outcome (O) and study design (S).

Outcome (O)	Population (P)	Intervention / comparator	Estimate	Design (S)	Source
RSV-related hospital admission, pooled real-world studies severity: hospitalisation case definition: RSV-related hospital admissions in post-licensure observational studies	adults aged 60 years or older country: United States, United Kingdom, Italy, Australia, Czech Republic, Switzerland, France, Canada, Israel period: studies published December 2023 to October 2025 50-64y65+	RSV vaccines for older adults (Arexvy, Abrysvo, mResvia), pooled platform: protein subunit and mRNA, pooled doses: 1 time since vaccination: mostly first season vs unvaccinated or test-negative, per included study	74.8 (66.8–82.9) VE (%)	meta-analysis 6 studies	Trusinska et al. 2026 Lancet Reg Health Eur quote Among adults aged ≥60 years, pooled estimates of vaccine effectiveness were 75.3% (95% CI: 73.7-76.9; three studies) against any laboratory-confirmed RSV-positive infection, 76.4% (95% CI: 74.2-78.5; four studies) against RSV-related emergency department or urgent care visits, 74.8% (95% CI: 66.8-82.9; six studies) against RSV-related hospital admissions, and 79.8% (95% CI: 68.1-91.5; four studies) against severe RSV-associated disease. abstract, FINDINGS Random-effects pooling across products and designs; most included studies are first-season. Severe RSV disease in the same abstract: 79.8% (68.1-91.5).
RSV-associated lower respiratory tract disease with two or more symptoms, all available follow-up severity: lower respiratory tract disease case definition: Symptomatic laboratory-confirmed RSV-LRTD with two or more lower respiratory symptoms	adults aged 60 years or older country: multinational period: 2021-2024 50-64y65+	mRNA-1345 (mResvia) platform: mRNA doses: 1 time since vaccination: all available follow-up, median 18.8 months vs placebo	47.4 (35.0–57.4) VE (%) follow-up: median 18.8 months, range 0.5-24 months	expert body	cdc.gov quote Using all available follow-up time (median = 18.8 months per participant; range = 0.5–24 months), efficacy of mResvia was 47.4% (95% CI = 35.0%–57.4%) against RSV-LRTD with two or more symptoms and 48.4% (95% CI = 27.9%–63.1%) against RSV-LRTD with three or more symptoms (Moderna, mRNA-1345 phase 2/3 clinical trial, unpublished data, 2024) ( 7 ). Vaccine Efficacy and Safety, mRNA RSV Vaccine, Vaccine efficacy paragraph ACIP's summary of manufacturer data (unpublished at the time) from the ConquerRSV trial. Barely more than half the primary-analysis figure at a median of under four months (record above), showing substantial waning. The trial was not powered for hospitalisation or death.
RSV-associated lower respiratory tract disease with two or more symptoms, 14 days to 12 months after vaccination severity: lower respiratory tract disease case definition: Symptomatic laboratory-confirmed RSV-LRTD with two or more symptoms	adults aged 60 years or older country: multinational period: 2021-2024 50-64y65+	mRNA-1345 (mResvia) platform: mRNA doses: 1 time since vaccination: 14 days to 12 months vs placebo	56.1 (42.2–66.7) VE (%) follow-up: 14 days to 12 months	expert body	cdc.gov quote Efficacy of 1 dose of Moderna mResvia vaccine against respiratory syncytial virus–associated lower respiratory tract disease among adults aged ≥60 years during phase 2/3 pivotal efficacy trial — multiple countries, 2021–2024 Efficacy evaluation period \| Vaccine efficacy against outcome, % (95% CI)* \| RSV-associated LRTD with ≥2 symptoms † \| RSV-associated LRTD with ≥3 symptoms † \| All available follow-up time § \| 47.4 (35.0 to 57.4) \| 48.4 (27.9 to 63.1) \| 14 days–4 months postvaccination ¶ \| 78.7 (62.8 to 87.9) \| 80.9 (50.1 to 92.7) \| 14 days–12 months postvaccination \| 56.1 (42.2 to 66.7) \| 54.9 (30.5 to 70.7) \| 12–24 months postvaccination \| 30.0 (1.1 to 50.7) \| 36.0 (–12.6 to 64.3) \| Abbreviations: LRTD = lower respiratory tract disease; RSV = respiratory syncytial virus; RT-PCR = reverse transcription–polymerase chain reaction; VE = vaccine efficacy. * Manufacturer-calculated efficacy based on hazard ratios. Table 1 Manufacturer-calculated efficacy based on hazard ratios, as tabulated by ACIP. The three-or-more-symptom figure in the same row is 54.9 (30.5-70.7).
RSV-associated lower respiratory tract disease with two or more symptoms, 12 to 24 months after vaccination severity: lower respiratory tract disease case definition: Symptomatic laboratory-confirmed RSV-LRTD with two or more symptoms	adults aged 60 years or older country: multinational period: 2021-2024 50-64y65+	mRNA-1345 (mResvia) platform: mRNA doses: 1 time since vaccination: 12 to 24 months vs placebo	30.0 (1.1–50.7) VE (%) follow-up: 12 to 24 months	expert body	cdc.gov quote Efficacy of 1 dose of Moderna mResvia vaccine against respiratory syncytial virus–associated lower respiratory tract disease among adults aged ≥60 years during phase 2/3 pivotal efficacy trial — multiple countries, 2021–2024 Efficacy evaluation period \| Vaccine efficacy against outcome, % (95% CI)* \| RSV-associated LRTD with ≥2 symptoms † \| RSV-associated LRTD with ≥3 symptoms † \| All available follow-up time § \| 47.4 (35.0 to 57.4) \| 48.4 (27.9 to 63.1) \| 14 days–4 months postvaccination ¶ \| 78.7 (62.8 to 87.9) \| 80.9 (50.1 to 92.7) \| 14 days–12 months postvaccination \| 56.1 (42.2 to 66.7) \| 54.9 (30.5 to 70.7) \| 12–24 months postvaccination \| 30.0 (1.1 to 50.7) \| 36.0 (–12.6 to 64.3) \| Abbreviations: LRTD = lower respiratory tract disease; RSV = respiratory syncytial virus; RT-PCR = reverse transcription–polymerase chain reaction; VE = vaccine efficacy. * Manufacturer-calculated efficacy based on hazard ratios. Table 1 The second-year estimate for the mRNA product; the lower bound sits just above zero, and the three-or-more-symptom estimate in the same row (36.0, -12.6 to 64.3) crosses zero. This is the clearest published waning signal among the three adult products.
RT-PCR-confirmed RSV-related lower respiratory tract disease severity: lower respiratory tract disease case definition: RSV-LRTD confirmed by RT-PCR, first RSV season	adults 60 years of age or older country: international, 17 countries period: 2021-2022 season n: 24,966 participants 50-64y65+	RSVPreF3 OA (Arexvy, AS01E-adjuvanted) platform: recombinant protein subunit, adjuvanted doses: 1 time since vaccination: one RSV season vs placebo	82.6 (57.9–94.1) VE (%) follow-up: median 6.7 months	RCT	Papi et al. 2023 N Engl J Med quote Over a median follow-up of 6.7 months, vaccine efficacy against RT-PCR-confirmed RSV-related lower respiratory tract disease was 82.6% (96.95% confidence interval [CI], 57.9 to 94.1), with 7 cases (1.0 per 1000 participant-years) in the vaccine group and 40 cases (5.8 per 1000 participant-years) in the placebo group. abstract, RESULTS Interval is a 96.95% CI, as the trial reports it. Seven cases in the vaccine group versus 40 in placebo: 1.0 vs 5.8 per 1000 participant-years, so the absolute risk reduction is about 5 cases per 1000 person-years in season one.
Severe RSV-related lower respiratory tract disease severity: severe LRTD case definition: Severe RSV-LRTD assessed on clinical signs or by the investigator	adults 60 years of age or older country: international, 17 countries period: 2021-2022 season n: 24,966 participants 50-64y65+	RSVPreF3 OA (Arexvy) platform: recombinant protein subunit, adjuvanted doses: 1 time since vaccination: one RSV season vs placebo	94.1 (62.4–99.9) VE (%) follow-up: median 6.7 months	RCT	Papi et al. 2023 N Engl J Med quote Vaccine efficacy was 94.1% (95% CI, 62.4 to 99.9) against severe RSV-related lower respiratory tract disease (assessed on the basis of clinical signs or by the investigator) and 71.7% (95% CI, 56.2 to 82.3) against RSV-related acute respiratory infection. abstract, RESULTS Wide interval because severe cases were few. Not a hospitalisation endpoint; the trial was not powered for hospitalisation or death.
RSV-related acute respiratory infection (any severity) severity: any symptomatic infection case definition: RT-PCR-confirmed RSV acute respiratory infection	adults 60 years of age or older country: international, 17 countries period: 2021-2022 season n: 24,966 participants 50-64y65+	RSVPreF3 OA (Arexvy) platform: recombinant protein subunit, adjuvanted doses: 1 time since vaccination: one RSV season vs placebo	71.7 (56.2–82.3) VE (%) follow-up: median 6.7 months	RCT	Papi et al. 2023 N Engl J Med quote Vaccine efficacy was 94.1% (95% CI, 62.4 to 99.9) against severe RSV-related lower respiratory tract disease (assessed on the basis of clinical signs or by the investigator) and 71.7% (95% CI, 56.2 to 82.3) against RSV-related acute respiratory infection. abstract, RESULTS Lower than the LRTD figure: the vaccine prevents a smaller share of mild infections than of lower respiratory disease.
RSV-related lower respiratory tract disease by subtype (RSV A) severity: lower respiratory tract disease strain: RSV A case definition: RT-PCR-confirmed RSV-LRTD, subtype A	adults 60 years of age or older country: international period: 2021-2022 season 50-64y65+	RSVPreF3 OA (Arexvy) platform: recombinant protein subunit, adjuvanted doses: 1 time since vaccination: one RSV season vs placebo	84.6 VE (%)	RCT	Papi et al. 2023 N Engl J Med quote Vaccine efficacy was similar against the RSV A and B subtypes (for RSV-related lower respiratory tract disease: 84.6% and 80.9%, respectively; for RSV-related acute respiratory infection: 71.9% and 70.6%, respectively). abstract, RESULTS No CI given in the abstract for the subtype estimates. RSV B in the same sentence: 80.9%.
RSV-related lower respiratory tract disease in adults with at least one cardiorespiratory or endocrine/metabolic condition severity: lower respiratory tract disease case definition: First RSV-LRTD episode in the subgroup with coexisting conditions of interest	adults 60 years or older with at least one coexisting condition of interest risk group: chronic cardiorespiratory or endocrine/metabolic conditions country: international period: 2021-2022 season 50-64y65+	RSVPreF3 OA (Arexvy) platform: recombinant protein subunit, adjuvanted doses: 1 time since vaccination: one RSV season vs placebo	94.6 VE (%) follow-up: median 6.7 months	RCT	Feldman et al. 2024 Clin Infect Dis quote Efficacy against RSV-LRTD was high in participants with ≥1 condition of interest (94.6%), ≥1 cardiorespiratory (92.1%), ≥1 endocrine/metabolic (100%), and ≥2 conditions of interest (92.0%). abstract, RESULTS Subgroup of the AReSVi trial; the abstract gives no CI. Efficacy in those with two or more conditions was similar in the same sentence. Medically stable participants only; frail and institutionalised adults were under-represented.
RSV-related lower respiratory tract disease over two RSV seasons after one dose severity: lower respiratory tract disease case definition: RT-PCR-confirmed RSV-LRTD, cumulative over two seasons	adults 60 years or older country: international period: 2021-2023 n: 24 967 participants 50-64y65+	RSVPreF3 OA (Arexvy) platform: recombinant protein subunit, adjuvanted doses: 1 time since vaccination: two RSV seasons vs placebo	67.2 (48.2–80.0) VE (%) follow-up: median 17.8 months	RCT	Ison et al. 2024 Clin Infect Dis quote Efficacy over 2 seasons of 1 RSVPreF3 OA dose was 67.2% (97.5% CI: 48.2-80.0%) against RSV-LRTD and 78.8% (95% CI: 52.6-92.0%) against severe RSV-LRTD. abstract, RESULTS 97.5% CI as reported. Cumulative two-season efficacy is lower than season-one efficacy (record above), which is the waning signal. Severe RSV-LRTD over the same period is the next record.
Severe RSV-related lower respiratory tract disease over two RSV seasons after one dose severity: severe LRTD case definition: Severe RSV-LRTD, cumulative over two seasons	adults 60 years or older country: international period: 2021-2023 50-64y65+	RSVPreF3 OA (Arexvy) platform: recombinant protein subunit, adjuvanted doses: 1 time since vaccination: two RSV seasons vs placebo	78.8 (52.6–92.0) VE (%) follow-up: median 17.8 months	RCT	Ison et al. 2024 Clin Infect Dis quote Efficacy over 2 seasons of 1 RSVPreF3 OA dose was 67.2% (97.5% CI: 48.2-80.0%) against RSV-LRTD and 78.8% (95% CI: 52.6-92.0%) against severe RSV-LRTD. abstract, RESULTS Protection against severe disease held up better over two seasons than protection against any LRTD.
RSV-related lower respiratory tract disease over two seasons, one dose plus revaccination at 1 year severity: lower respiratory tract disease case definition: RT-PCR-confirmed RSV-LRTD, cumulative over two seasons	adults 60 years or older country: international period: 2021-2023 n: 6242 revaccinated 50-64y65+	RSVPreF3 OA (Arexvy) platform: recombinant protein subunit, adjuvanted doses: 2 schedule: second dose 1 year after the first time since vaccination: two RSV seasons vs placebo	67.1 (48.1–80.0) VE (%) follow-up: median 17.8 months	RCT	Ison et al. 2024 Clin Infect Dis quote Efficacy over 2 seasons of a first dose followed by revaccination was 67.1% (97.5% CI: 48.1-80.0%) against RSV-LRTD and 78.8% (95% CI: 52.5-92.0%) against severe RSV-LRTD. abstract, RESULTS 97.5% CI. Identical to the single-dose figure above: revaccination at one year added no measurable efficacy in the overall population, which is why a single dose is recommended.
RSV-related lower respiratory tract disease over three RSV seasons after one dose severity: lower respiratory tract disease case definition: RT-PCR-confirmed RSV-LRTD, cumulative over three seasons	adults 60 years or older country: 17 countries in Africa, Asia, Oceania, Europe and North America period: 2021-2024 n: 12 468 vaccine and 12 498 placebo recipients 50-64y65+	RSVPreF3 OA (Arexvy) platform: recombinant protein subunit, adjuvanted doses: 1 time since vaccination: three RSV seasons vs placebo	62.9 (46.7–74.8) VE (%) follow-up: median 30.6 months from day 15 post-dose	RCT	Ison et al. 2025 Lancet Respir Med quote Cumulative efficacy over three seasons of one RSVPreF3 OA dose was 62·9% (97·5% CI 46·7-74·8) against RSV-LRTD, 69·8% (42·2-85·7) against RSV A-related LRTD, and 58·6% (35·9-74·1) against RSV B-related LRTD (median follow-up from day 15 post-dose one 30·6 months [IQR 26·2-32·0]). abstract, FINDINGS 97.5% CI. The decline from season one through two and three seasons across these records is the published waning curve; the abstract states efficacy decreased over time. Subtype estimates are the next two records.
RSV A-related lower respiratory tract disease over three seasons severity: lower respiratory tract disease strain: RSV A case definition: RT-PCR-confirmed RSV-LRTD, subtype A	adults 60 years or older country: 17 countries period: 2021-2024 50-64y65+	RSVPreF3 OA (Arexvy) platform: recombinant protein subunit, adjuvanted doses: 1 time since vaccination: three RSV seasons vs placebo	69.8 (42.2–85.7) VE (%) follow-up: median 30.6 months	RCT	Ison et al. 2025 Lancet Respir Med quote Cumulative efficacy over three seasons of one RSVPreF3 OA dose was 62·9% (97·5% CI 46·7-74·8) against RSV-LRTD, 69·8% (42·2-85·7) against RSV A-related LRTD, and 58·6% (35·9-74·1) against RSV B-related LRTD (median follow-up from day 15 post-dose one 30·6 months [IQR 26·2-32·0]). abstract, FINDINGS 97.5% CI.
RSV B-related lower respiratory tract disease over three seasons severity: lower respiratory tract disease strain: RSV B case definition: RT-PCR-confirmed RSV-LRTD, subtype B	adults 60 years or older country: 17 countries period: 2021-2024 50-64y65+	RSVPreF3 OA (Arexvy) platform: recombinant protein subunit, adjuvanted doses: 1 time since vaccination: three RSV seasons vs placebo	58.6 (35.9–74.1) VE (%) follow-up: median 30.6 months	RCT	Ison et al. 2025 Lancet Respir Med quote Cumulative efficacy over three seasons of one RSVPreF3 OA dose was 62·9% (97·5% CI 46·7-74·8) against RSV-LRTD, 69·8% (42·2-85·7) against RSV A-related LRTD, and 58·6% (35·9-74·1) against RSV B-related LRTD (median follow-up from day 15 post-dose one 30·6 months [IQR 26·2-32·0]). abstract, FINDINGS 97.5% CI. Lower point estimate against RSV B than RSV A over three seasons, though intervals overlap.
RSV-associated lower respiratory tract illness with at least two signs or symptoms severity: lower respiratory tract illness case definition: Seasonal RSV-associated LRTI with at least two signs or symptoms, interim analysis	adults 60 years of age or older country: multinational period: first season, data cutoff July 2022 n: 34,284 participants 50-64y65+	RSVpreF bivalent (Abrysvo), 120 ug platform: recombinant protein subunit, unadjuvanted doses: 1 time since vaccination: one RSV season vs placebo	66.7 (28.8–85.8) VE (%)	RCT	Walsh et al. 2023 N Engl J Med quote RSV-associated lower respiratory tract illness with at least two signs or symptoms occurred in 11 participants in the vaccine group (1.19 cases per 1000 person-years of observation) and 33 participants in the placebo group (3.58 cases per 1000 person-years of observation) (vaccine efficacy, 66.7%; 96.66% confidence interval [CI], 28.8 to 85.8); 2 cases (0.22 cases per 1000 person-years of observation) and 14 cases (1.52 cases per 1000 person-years of observation), respectively, occurred with at least three signs or symptoms (vaccine efficacy, 85.7%; 96.66% CI, 32.0 to 98.7). abstract, RESULTS 96.66% CI as reported. Eleven cases in the vaccine group vs 33 in placebo (1.19 vs 3.58 per 1000 person-years). The same product is used for maternal vaccination.
RSV-associated lower respiratory tract illness with at least three signs or symptoms severity: more severe lower respiratory tract illness case definition: Seasonal RSV-associated LRTI with at least three signs or symptoms	adults 60 years of age or older country: multinational period: first season, data cutoff July 2022 n: 34,284 participants 50-64y65+	RSVpreF bivalent (Abrysvo), 120 ug platform: recombinant protein subunit, unadjuvanted doses: 1 time since vaccination: one RSV season vs placebo	85.7 (32.0–98.7) VE (%)	RCT	Walsh et al. 2023 N Engl J Med quote RSV-associated lower respiratory tract illness with at least two signs or symptoms occurred in 11 participants in the vaccine group (1.19 cases per 1000 person-years of observation) and 33 participants in the placebo group (3.58 cases per 1000 person-years of observation) (vaccine efficacy, 66.7%; 96.66% confidence interval [CI], 28.8 to 85.8); 2 cases (0.22 cases per 1000 person-years of observation) and 14 cases (1.52 cases per 1000 person-years of observation), respectively, occurred with at least three signs or symptoms (vaccine efficacy, 85.7%; 96.66% CI, 32.0 to 98.7). abstract, RESULTS 96.66% CI; based on 2 vs 14 cases, so the lower bound is low.
RSV-associated acute respiratory illness severity: any symptomatic infection case definition: RSV-associated acute respiratory illness, secondary endpoint	adults 60 years of age or older country: multinational period: first season, data cutoff July 2022 50-64y65+	RSVpreF bivalent (Abrysvo), 120 ug platform: recombinant protein subunit, unadjuvanted doses: 1 time since vaccination: one RSV season vs placebo	62.1 (37.1–77.9) VE (%)	RCT	Walsh et al. 2023 N Engl J Med quote RSV-associated acute respiratory illness occurred in 22 participants in the vaccine group (2.38 cases per 1000 person-years of observation) and 58 participants in the placebo group (6.30 cases per 1000 person-years of observation) (vaccine efficacy, 62.1%; 95% CI, 37.1 to 77.9). abstract, RESULTS 22 vs 58 cases (2.38 vs 6.30 per 1000 person-years).
RSV-associated lower respiratory tract disease with at least two signs or symptoms severity: lower respiratory tract disease case definition: RSV-LRTD with at least two signs or symptoms, primary analysis at 50% of anticipated cases	adults 60 years of age or older country: multinational period: 2021-2022 n: 35,541 participants 50-64y65+	mRNA-1345 (mResvia), 50 ug platform: mRNA doses: 1 time since vaccination: median 112 days vs placebo	83.7 (66.0–92.2) VE (%) follow-up: median 112 days	RCT	Wilson et al. 2023 N Engl J Med quote Vaccine efficacy was 83.7% (95.88% confidence interval [CI], 66.0 to 92.2) against RSV-associated lower respiratory tract disease with at least two signs or symptoms and 82.4% (96.36% CI, 34.8 to 95.3) against the disease with at least three signs or symptoms. abstract, RESULTS 95.88% CI. Short median follow-up (under 4 months); the longer follow-up figures from the ACIP review are in the records below and are markedly lower.
RSV-associated lower respiratory tract disease with at least three signs or symptoms severity: more severe lower respiratory tract disease case definition: RSV-LRTD with at least three signs or symptoms	adults 60 years of age or older country: multinational period: 2021-2022 50-64y65+	mRNA-1345 (mResvia), 50 ug platform: mRNA doses: 1 time since vaccination: median 112 days vs placebo	82.4 (34.8–95.3) VE (%) follow-up: median 112 days	RCT	Wilson et al. 2023 N Engl J Med quote Vaccine efficacy was 83.7% (95.88% confidence interval [CI], 66.0 to 92.2) against RSV-associated lower respiratory tract disease with at least two signs or symptoms and 82.4% (96.36% CI, 34.8 to 95.3) against the disease with at least three signs or symptoms. abstract, RESULTS 96.36% CI.
RSV-associated acute respiratory disease severity: any symptomatic infection case definition: RSV-associated acute respiratory disease, key secondary endpoint	adults 60 years of age or older country: multinational period: 2021-2022 50-64y65+	mRNA-1345 (mResvia), 50 ug platform: mRNA doses: 1 time since vaccination: median 112 days vs placebo	68.4 (50.9–79.7) VE (%) follow-up: median 112 days	RCT	Wilson et al. 2023 N Engl J Med quote Vaccine efficacy was 68.4% (95% CI, 50.9 to 79.7) against RSV-associated acute respiratory disease. abstract, RESULTS
RSV-associated hospitalisation, adults 60 or older without immunocompromising conditions severity: hospitalisation case definition: Hospitalisation with RSV-like illness and RSV testing in an electronic health records network, eight states	adults aged 60 years or older immune status: immunocompetent country: United States setting: hospital, VISION network period: October 2023 to March 2024 n: 28 271 hospitalisations 50-64y65+	RSVPreF3 OA (Arexvy) or RSVpreF (Abrysvo), not separated platform: recombinant protein subunit doses: 1 time since vaccination: first season after vaccination vs test-negative controls	80 (71–85) VE (%)	test-negative	Payne et al. 2024 Lancet quote FINDINGS: Among 28 271 hospitalisations for respiratory syncytial virus-like illness among adults aged at least 60 years without immunocompromising conditions, vaccine effectiveness was 80% (95% CI 71-85) against respiratory syncytial virus-associated hospitalisations, and vaccine effectiveness was 81% (52-92) against respiratory syncytial virus-associated critical illness (ICU admission or death, or both). abstract, FINDINGS First post-licensure season. VE was similar by age group and product. Immunocompromised adults in the same abstract are the next-but-one record.
RSV-associated critical illness (ICU admission or death) severity: ICU admission or death case definition: ICU admission or in-hospital death among RSV-positive hospitalised adults	adults aged 60 years or older immune status: immunocompetent country: United States period: October 2023 to March 2024 50-64y65+	RSVPreF3 OA (Arexvy) or RSVpreF (Abrysvo) platform: recombinant protein subunit doses: 1 time since vaccination: first season after vaccination vs test-negative controls	81 (52–92) VE (%)	test-negative	Payne et al. 2024 Lancet quote FINDINGS: Among 28 271 hospitalisations for respiratory syncytial virus-like illness among adults aged at least 60 years without immunocompromising conditions, vaccine effectiveness was 80% (95% CI 71-85) against respiratory syncytial virus-associated hospitalisations, and vaccine effectiveness was 81% (52-92) against respiratory syncytial virus-associated critical illness (ICU admission or death, or both). abstract, FINDINGS The only trial-or-real-world estimate here with death in the endpoint; the trials were not powered for it.
RSV-associated hospitalisation, adults 60 or older with immunocompromising conditions severity: hospitalisation case definition: Hospitalisation with RSV-like illness and RSV testing, immunocompromised subgroup	adults aged 60 years or older immune status: immunocompromising conditions country: United States period: October 2023 to March 2024 n: 8435 hospitalisations 50-64y65+	RSVPreF3 OA (Arexvy) or RSVpreF (Abrysvo) platform: recombinant protein subunit doses: 1 time since vaccination: first season after vaccination vs test-negative controls	73 (48–85) VE (%)	test-negative	Payne et al. 2024 Lancet quote Among 8435 hospitalisations for respiratory syncytial virus-like illness among adults with immunocompromising conditions, vaccine effectiveness was 73% (48-85) against associated hospitalisation. abstract, FINDINGS Immunocompromised adults were excluded from the pivotal trials, so this is the first evidence for them. Lower point estimate than immunocompetent adults, with overlapping intervals in season one; the two-season records below show a larger gap.
RSV-associated hospitalisation over two seasons severity: hospitalisation case definition: RSV-positive hospitalised adults with acute respiratory illness vs controls negative for RSV, SARS-CoV-2 and influenza, 26 hospitals in 20 states	adults aged 60 years or older, median 72 immune status: 26.3% immunocompromised country: United States setting: hospital, IVY network period: October 2023 to April 2025 n: 6958 adults (821 cases) 50-64y65+	RSV vaccine (any licensed product) platform: protein subunit or mRNA, not separated doses: 1 time since vaccination: up to two seasons vs test-negative controls	58 (45–68) VE (%)	test-negative	Surie et al. 2025 JAMA quote Estimated vaccine effectiveness against RSV-associated hospitalization was 58% (95% CI, 45%-68%) during 2 seasons and 69% (95% CI, 52%-81%) for same-season vaccination vs 48% (95% CI, 27%-63%; P = .06) for prior-season vaccination. abstract, RESULTS Includes a quarter immunocompromised, which lowers the overall figure. Same-season vs prior-season vaccination are the next records.
RSV-associated hospitalisation, vaccinated in the same season severity: hospitalisation case definition: As above, stratified by timing of vaccination	adults aged 60 years or older country: United States period: October 2023 to April 2025 50-64y65+	RSV vaccine (any licensed product) platform: protein subunit or mRNA doses: 1 time since vaccination: same season (under about 6 months) vs test-negative controls	69 (52–81) VE (%)	test-negative	Surie et al. 2025 JAMA quote Estimated vaccine effectiveness against RSV-associated hospitalization was 58% (95% CI, 45%-68%) during 2 seasons and 69% (95% CI, 52%-81%) for same-season vaccination vs 48% (95% CI, 27%-63%; P = .06) for prior-season vaccination. abstract, RESULTS Compare with prior-season vaccination 48% (27-63) in the same sentence; the difference had P = .06.
RSV-associated hospitalisation, vaccinated in the prior season severity: hospitalisation case definition: As above, stratified by timing of vaccination	adults aged 60 years or older country: United States period: October 2023 to April 2025 50-64y65+	RSV vaccine (any licensed product) platform: protein subunit or mRNA doses: 1 time since vaccination: prior season (roughly 6-18 months) vs test-negative controls	48 (27–63) VE (%)	test-negative	Surie et al. 2025 JAMA quote Estimated vaccine effectiveness against RSV-associated hospitalization was 58% (95% CI, 45%-68%) during 2 seasons and 69% (95% CI, 52%-81%) for same-season vaccination vs 48% (95% CI, 27%-63%; P = .06) for prior-season vaccination. abstract, RESULTS Second-season protection against hospitalisation is about two-thirds of first-season protection in this network; ACIP has not yet set a revaccination interval.
RSV-associated hospitalisation over two seasons, immunocompromised adults severity: hospitalisation case definition: As above, immunocompromised subgroup	adults aged 60 years or older immune status: immunocompromised country: United States period: October 2023 to April 2025 n: 1829 immunocompromised adults 50-64y65+	RSV vaccine (any licensed product) platform: protein subunit or mRNA doses: 1 time since vaccination: up to two seasons vs test-negative controls	30 (-9–55) VE (%)	test-negative	Surie et al. 2025 JAMA quote Estimated vaccine effectiveness during 2 seasons was significantly lower among immunocompromised adults (30%; 95% CI, -9% to 55%) than immunocompetent adults (67%; 95% CI, 53%-77%; P = .02) and among those with cardiovascular disease (56%; 95% CI, 32%-72%) vs without (80%; 95% CI, 62%-90%; P = .03). abstract, RESULTS The interval includes zero: no demonstrated protection over two seasons in immunocompromised adults in this network, versus 67% (53-77) in immunocompetent adults in the same sentence (P = .02). Cardiovascular disease also lowered VE (56% vs 80%).
RSV-associated hospitalisation, 0 to 18 months after vaccination severity: hospitalisation case definition: RSV-associated hospitalisation in matched vaccinated and unvaccinated veterans, target trial emulation	veterans 60 years and older, median 76.1 sex: 94.5% male country: United States setting: Veterans Health Administration period: September 2023 to March 2025 n: 288 111 vaccinated matched to 1 075 893 controls 50-64y65+	recombinant stabilised prefusion F protein RSV vaccine (Arexvy or Abrysvo) platform: recombinant protein subunit doses: 1 time since vaccination: 0 to 18 months (cumulative) vs matched unvaccinated veterans	57.3 (47.3–66.4) VE (%) = 100 x (1 - risk ratio) follow-up: 0 to 18 months	cohort	Bajema et al. 2026 JAMA Intern Med quote During the same period, effectiveness decreased from 84.9% (95% CI, 78.4%-90.2%) to 60.5% (95% CI, 56.4%-65.7%) for emergency visits and 88.9% (95% CI, 77.9%-95.7%) to 57.3% (95% CI, 47.3%-66.4%) for hospitalizations and was 92.5% (95% CI, 61.1%-100.0%) and 71.9% (95% CI, 42.8%-90.0%) for intensive care unit admissions. abstract, RESULTS The same sentence gives 88.9% (77.9-95.7) over 0 to 1 month, the starting point of the decline. Predominantly male population. Residual confounding by health-seeking behaviour is the main risk in a vaccinated-vs-unvaccinated cohort.
Documented RSV infection, immunocompromised veterans, 0 to 18 months severity: any documented infection case definition: Any positive RSV test, immunocompromised subgroup	veterans 60 years and older immune status: immunocompromised country: United States setting: Veterans Health Administration period: September 2023 to March 2025 50-64y65+	recombinant prefusion F protein RSV vaccine platform: recombinant protein subunit doses: 1 time since vaccination: 0 to 18 months (cumulative) vs matched unvaccinated immunocompromised veterans	39.7 (23.9–52.7) VE (%) = 100 x (1 - risk ratio) follow-up: 0 to 18 months	cohort	Bajema et al. 2026 JAMA Intern Med quote Among immunocompromised individuals, protection against documented infections decreased from 75.2% (95% CI, 52.5%-89.3%) to 39.7% (95% CI, 23.9%-52.7%). abstract, RESULTS Protection fell by nearly half over eighteen months in immunocompromised people, a steeper decline than in the overall cohort.
RSV-related hospitalisation, adults aged 74-79, pooled across four UK nations severity: hospitalisation case definition: Hospitalised adults with laboratory-confirmed RSV vs RSV-negative hospitalised controls, excluding SARS-CoV-2 and influenza positives, linked national data	adults aged 74-79 years country: United Kingdom (England, Wales, Scotland, Northern Ireland) setting: hospital, national linked data period: 2024-25 season n: 11,117 adults (826 RSV cases) 65+	RSVpreF bivalent (Abrysvo) platform: recombinant protein subunit, unadjuvanted doses: 1 time since vaccination: first programme season vs test-negative hospitalised controls	75 (69–80) VE (%)	test-negative	Bucholc et al. 2026 Lancet Reg Health Eur quote Pooled fixed-effects VE was 75% (69-80; I 2 = 0%). abstract, FINDINGS Unfunded national evaluation; I2 of 0% across nations. The UK programme uses Abrysvo only, so this is a product-specific estimate in the 75-plus band that ACIP recommends universally.
RSV-related lower respiratory tract disease hospitalisation or emergency department visit, third season after vaccination severity: hospitalisation or emergency department visit case definition: RSV-positive LRTD hospitalisation or ED visit without co-infection vs controls positive for a non-vaccine-preventable pathogen	adults aged 60 years or older country: United States (Kaiser Permanente Southern California) period: November 2023 to April 2026 50-64y65+	RSVpreF bivalent (Abrysvo) platform: recombinant protein subunit, unadjuvanted doses: 1 time since vaccination: third season after vaccination vs test-negative controls	51 (-12–78) VE (%)	test-negative	Tartof et al. 2026 Infect Dis Ther quote RESULTS: Overall adjusted VE against RSV-related LRTD hospitalization/ED visits was 80% (95% CI 68-87), 70% (95% CI 53-81), and 51% (95% CI -12-78) in the first, second, and third season after vaccination, respectively. abstract, RESULTS The same sentence gives 80% (68-87) in season one and 70% (53-81) in season two. The third-season LRTD interval crosses zero because events were few; the ARI endpoint in season three was more precise and remained positive. Pfizer-sponsored study.
RSV-associated lower respiratory tract disease hospitalisation or emergency visit, immunocompromised adults, second season severity: hospitalisation or emergency department visit case definition: RSV-positive LRTD hospitalisation or ED visit, immunocompromised subgroup	adults aged 60 years or older immune status: immunocompromised country: United States (Kaiser Permanente Southern California) period: November 2023 to April 2025 50-64y65+	RSVpreF bivalent (Abrysvo) platform: recombinant protein subunit, unadjuvanted doses: 1 time since vaccination: second season after vaccination vs test-negative controls	54 (-48–85) VE (%)	test-negative	Tartof et al. 2026 Lancet Reg Health Am quote VE in immunocompromised adults appeared to decrease more quickly: 74% (95% CI: 37-89) first season to 54% (95% CI: -48 to 85) second season. abstract, FINDINGS First-season figure in the same sentence: 74% (37-89). Overall (all adults) VE in the same abstract declined only modestly across the two seasons, so the drop is specific to the immunocompromised. Pfizer-sponsored.
RSV-associated acute respiratory infection diagnosis severity: any medically attended infection case definition: RSV-positive test among adults with acute respiratory infection tested for RSV, electronic health records of over 270 million patients	adults aged 60 years or older country: United States setting: national electronic health record platform period: October 2023 to April 2024 n: 787 822 tested, 53 963 positive 50-64y65+	RSV protein subunit vaccine (Arexvy or Abrysvo) platform: recombinant protein subunit doses: 1 time since vaccination: first season vs test-negative controls	75.1 (73.6–76.4) VE (%)	test-negative	Fry et al. 2025 JAMA Netw Open quote Overall, VE was 75.1% (95% CI, 73.6%-76.4%) against ARI and was similar for age groups of 60 to 74 years and 75 years or older and against urgent care visits or hospitalizations. abstract, RESULTS Similar for 60-74 and 75-plus and for urgent care or hospitalisation per the same abstract. The stem-cell-transplant subgroup is the next record.
RSV-associated acute respiratory infection, stem cell transplant recipients aged 60-74 severity: any medically attended infection case definition: RSV-positive test among stem cell transplant recipients with ARI	adults aged 60-74 years immune status: stem cell transplant recipients country: United States period: October 2023 to April 2024 50-64y65+	RSV protein subunit vaccine (Arexvy or Abrysvo) platform: recombinant protein subunit doses: 1 time since vaccination: first season vs test-negative controls	29.4 (3.5–48.4) VE (%)	test-negative	Fry et al. 2025 JAMA Netw Open quote Immunocompromised patients had a VE from 67.0% (95% CI, 62.6%-70.9%) for patients aged 60 to 74 years to 73.1% (95% CI, 69.9%-76.0%) for those aged 75 years or older, and the lowest VE (ie, from 29.4% [95% CI, 3.5%-48.4%] for patients aged 60-74 years to 44.4% [95% CI, 1.0%-68.8%] for those aged ≥75 years) was for a subgroup of patients who received stem cell transplants. abstract, RESULTS The lowest VE subgroup in the study; 44.4% (1.0-68.8) for transplant recipients aged 75 or older in the same sentence. Immunocompromised patients overall were 67.0% to 73.1%.

Vaccine safety and adverse events

Harms measured after vaccination against an unvaccinated or baseline comparator. Kept separate from post-acute sequelae, which follow the disease, not the vaccine.

Outcome (O)	Population (P)	Intervention / comparator	Estimate	Design (S)	Source
Severe reactogenicity events after mResvia severity: severe reactogenicity case definition: Severe solicited reactogenicity events in the pooled mResvia trials	adults aged 60 years or older country: multinational period: 2021-2024 50-64y65+	mRNA-1345 (mResvia) platform: mRNA doses: 1 vs placebo	1.54 (1.40–1.68) pooled relative risk	expert body	cdc.gov quote Severe reactogenicity events were more common among mResvia recipients than among placebo recipients §§ (pooled relative risk = 1.54 [95% CI = 1.40–1.68]); (Supplementary Table, https://stacks.cdc.gov/view/cdc/159161 ) ( 4 ). Vaccine Efficacy and Safety, mRNA RSV Vaccine, Vaccine safety paragraph The same paragraph reports a pooled relative risk for serious adverse events of one and no GBS, myocarditis or pericarditis within six weeks in the trials. Trials are too small to detect GBS at the rates seen post-licensure for the protein subunit vaccines.
Guillain-Barre syndrome within 42 days of RSVpreF vaccination severity: Guillain-Barre syndrome case definition: GBS from the intravenous immunoglobulin registry and GBS-coded hospital discharges, 0-42 day risk window	adults aged 75-79 years country: England setting: national programme, 2.5 million eligible period: September 2024 onward, six-month analysis 65+	RSVpreF bivalent (Abrysvo) platform: recombinant protein subunit, unadjuvanted doses: 1 vs the same individuals outside the 0-42 day post-vaccination window	3.34 (2.12–5.28) relative incidence, risk window vs control	SCCS	Stowe et al. 2025 Nat Commun quote Final results were consistent, with the self-controlled case-series estimating a relative incidence of 3.34 (95% CI: 2.12-5.28) and an attributable risk of 23 (95% CI: 17-26) cases per million doses. abstract Attributable risk in the same sentence: 23 (17-26) cases per million doses. The authors judge this far exceeded by benefit; compare with the GBS risk after RSV disease itself (the post-acute GBS record) and the preventable hospitalisations per million doses in the ACIP table.
Guillain-Barre syndrome attributable to RSVpreF vaccination severity: Guillain-Barre syndrome case definition: Excess GBS cases per million doses from the self-controlled case series	adults aged 75-79 years country: England period: September 2024 onward 65+	RSVpreF bivalent (Abrysvo) platform: recombinant protein subunit, unadjuvanted doses: 1 vs background rate in the same individuals outside the risk window	23 (17–26) attributable risk per million doses per million RSVpreF doses	SCCS	Stowe et al. 2025 Nat Commun quote Final results were consistent, with the self-controlled case-series estimating a relative incidence of 3.34 (95% CI: 2.12-5.28) and an attributable risk of 23 (95% CI: 17-26) cases per million doses. abstract Higher than the US estimates (next record), possibly because England's programme targets a single older age band and uses an IVIG registry for ascertainment.
Guillain-Barre syndrome within 6 weeks of RSV vaccination, by product severity: Guillain-Barre syndrome case definition: GBS diagnosis within 6 weeks after vaccination, self-controlled case series in electronic health records	adults aged 60 years or older country: United States period: July 2023 to June 2024 n: 4 746 518 vaccine recipients 50-64y65+	RSVpreF bivalent (Abrysvo); Arexvy in the same sentence 5.2 platform: recombinant protein subunit doses: 1 vs the same individuals outside the 6-week risk window	18.2 excess cases per 1 000 000 doses per 1 000 000 RSVpreF (Abrysvo) doses	SCCS	Fry et al. 2025 JAMA Netw Open quote An excess of 5.2 cases (RSVPreF3+AS01) or 18.2 cases (RSVPreF) of Guillain-Barré syndrome were diagnosed per 1 000 000 doses of RSV vaccine administered. abstract, RESULTS The excess was statistically significant for RSVpreF but not for RSVPreF3+AS01 (Arexvy) per the abstract. No excess risk of immune thrombocytopenic purpura was detected for either product.

Recurrent wheeze and asthma after infant RSV infection Respiratory syncytial virus

Post-acute and long-term sequelae

What can follow the acute illness: chronic disease, disability, cancers, congenital syndromes, post-infectious conditions.

Outcome (O)	Population (P)	Comparator	Estimate	Design (S)	Source
Asthma or recurrent wheeze at age 18 after RSV bronchiolitis hospitalisation in infancy severity: asthma or recurrent wheeze case definition: Questionnaire and clinical examination at age 18 in a cohort hospitalised with RSV bronchiolitis in the first year of life, with matched controls	18 years, exposure in first year of life prior infection: hospitalised with RSV bronchiolitis in infancy vaccination status: unvaccinated country: Sweden setting: hospital-recruited cohort n: 46 RSV subjects and 92 controls 12-17y	vs matched controls without RSV bronchiolitis hospitalisation (9%)	39 prevalence of asthma/recurrent wheeze at 18 years (%) follow-up: 18 years	cohort	Sigurs et al. 2010 Thorax quote RESULTS: Increased prevalence of asthma/RW (39% vs 9%), clinical allergy (43% vs 17%) and sensitisation to perennial allergens (41% vs 14%) were present at age 18 in the RSV cohort compared with controls. abstract, RESULTS Small cohort of severe (hospitalised) cases. Shared predisposition (an infant prone to wheeze is more likely both to be hospitalised with RSV and to develop asthma) cannot be separated from a causal effect in this design. Clinical allergy and perennial sensitisation were also higher in the same sentence.
Persistent or relapsing wheeze with early allergic sensitisation by age 18 after infant RSV bronchiolitis severity: persistent allergic asthma phenotype case definition: Longitudinal wheeze pattern combined with allergic sensitisation in the 18-year follow-up	18 years, exposure in first year of life prior infection: hospitalised with RSV bronchiolitis in infancy vaccination status: unvaccinated country: Sweden n: 46 RSV subjects and 92 controls 12-17y	vs matched controls (1%)	30 prevalence of persistent/relapsing wheeze with early sensitisation (%) follow-up: 18 years	cohort	Sigurs et al. 2010 Thorax quote Persistent/relapsing wheeze associated with early allergic sensitisation predominated in the RSV cohort compared with controls (30% vs 1%). abstract, RESULTS Same cohort and same confounding caveat as the record above; a specific phenotype rather than any asthma.
Recurrent wheezing in the fifth year of life after prolonged RSV hospitalisation in infancy severity: recurrent wheeze case definition: Recurrent wheezing from outpatient visits, inpatient stays and asthma prescriptions in an integrated health system; RSV laboratory-confirmed and medically attended in the first year	fifth year of life, exposure in first year prior infection: prolonged RSV hospitalisation in infancy vaccination status: unvaccinated country: United States (Northern California) setting: integrated health care system period: born 1996-2004 n: 72 602 children 1-4y	vs children without laboratory-confirmed RSV infection in infancy	2.59 (1.49–4.50) adjusted OR vs children without RSV infection in infancy follow-up: to fifth year of life	cohort	Escobar et al. 2013 BMC Pediatr quote In multivariate analyses, increasing severity of respiratory syncytial virus infection was significantly associated with recurrent wheezing in year 5; compared with children without RSV infection in infancy, children who only had an outpatient RSV encounter had an adjusted odds ratio of 1.38 (95% CI,1.03-1.85), while children with a prolonged RSV hospitalization had an adjusted odds ratio of 2.59 (95% CI, 1.49-4.50). abstract, RESULTS Children born at thirty-two weeks or later. Severity gradient (outpatient-only RSV in the next record) supports a dose-response but confounding by underlying airway predisposition remains.
Recurrent wheezing in the fifth year of life after outpatient-only RSV infection in infancy severity: recurrent wheeze case definition: Recurrent wheezing from outpatient visits, inpatient stays and asthma prescriptions; RSV laboratory-confirmed, medically attended, outpatient only	fifth year of life, exposure in first year prior infection: outpatient medically attended RSV infection in infancy vaccination status: unvaccinated country: United States (Northern California) period: born 1996-2004 n: 72 602 children 1-4y	vs children without laboratory-confirmed RSV infection in infancy	1.38 (1.03–1.85) adjusted OR vs children without RSV infection in infancy follow-up: to fifth year of life	cohort	Escobar et al. 2013 BMC Pediatr quote In multivariate analyses, increasing severity of respiratory syncytial virus infection was significantly associated with recurrent wheezing in year 5; compared with children without RSV infection in infancy, children who only had an outpatient RSV encounter had an adjusted odds ratio of 1.38 (95% CI,1.03-1.85), while children with a prolonged RSV hospitalization had an adjusted odds ratio of 2.59 (95% CI, 1.49-4.50). abstract, RESULTS Milder RSV carries a smaller excess than prolonged hospitalisation (record above). Children with unrecognised RSV are in the comparator group, which biases toward the null.
Recurrent wheezing in the fifth year of life among infants hospitalised with RSV severity: recurrent wheeze case definition: Recurrent wheezing in the fifth year of life	fifth year of life prior infection: RSV hospitalisation in infancy vaccination status: unvaccinated country: United States (Northern California) period: born 1996-2004 1-4y	vs whole cohort rate of 4.7% in the fifth year	12.5 proportion with recurrent wheezing in year 5 (%) follow-up: to fifth year of life	cohort	Escobar et al. 2013 BMC Pediatr quote Recurrent wheezing rates varied by risk status: the rate was 12.5% among infants with RSV hospitalization, 8% among infants 32-33 weeks gestation, and 18% in infants with bronchopulmonary dysplasia. abstract, RESULTS Absolute rate to set beside the odds ratios above. Infants with bronchopulmonary dysplasia had 18% in the same sentence.
Current asthma at age 5 years, not infected vs infected with RSV in the first year of life severity: current asthma case definition: RSV infection in the first year ascertained by passive and active surveillance with molecular and serological testing; 5-year current asthma by parental report and clinical criteria	5 years, exposure in first year of life prior infection: RSV infection (any severity) in infancy vs none vaccination status: unvaccinated country: United States (middle Tennessee) setting: community birth cohort period: born 2012-2013 n: 1741 children with infection status, 1257 with 5-year asthma data 5-11y	vs children infected with RSV during infancy	0.74 (0.58–0.94) adjusted RR for 5-year asthma, uninfected vs infected follow-up: 5 years	cohort	Rosas-Salazar et al. 2023 Lancet quote Not being infected with RSV during infancy was associated with a 26% lower risk of 5-year current asthma than being infected with RSV during infancy (adjusted RR 0·74, 95% CI 0·58-0·94, p=0·014). abstract, FINDINGS Healthy term infants, exposure includes mild and asymptomatic infection, so this is not a hospitalised-only estimate. Adjusted for sex, race, breastfeeding, day care, smoke exposure and maternal asthma; the authors say causality needs a prevention trial. The same abstract gives the raw asthma proportions in uninfected and infected children.
Population attributable fraction of 5-year asthma due to RSV infection in infancy severity: current asthma case definition: Estimated proportion of 5-year current asthma cases preventable by avoiding infant RSV infection	5 years prior infection: RSV infection in infancy vaccination status: unvaccinated country: United States (middle Tennessee) period: born 2012-2013 n: 1741 children 5-11y	vs children not infected with RSV in infancy	15 (2.2–26.8) population attributable fraction (%) follow-up: 5 years	cohort	Rosas-Salazar et al. 2023 Lancet quote The estimated proportion of 5-year current asthma cases that could be prevented by avoiding RSV infection during infancy was 15% (95% CI 2·2-26·8). abstract, FINDINGS A causal interpretation is assumed by the attributable-fraction calculation; the wide interval reflects a single cohort. Not an RCT of prevention.

Gaps

No RSV-infant hospitalisation or death rate was compiled from a low-income-country primary surveillance study with month-of-age resolution; the LMIC figures here are modelled (Li 2022, Shi 2017, Antillon 2023). A search for LMIC in-hospital case fatality by age returned only metapneumovirus and modelling papers.
No published efficacy of Arexvy or Abrysvo stratified by 60-69, 70-79 and 80-plus with confidence intervals was found in the abstracts cached: AReSVi-006 reports only that efficacy was observed in each age band, and RENOIR gives no age split in the abstract. Age-band efficacy sits in full-text supplements that were not snapshotted.
No second-season efficacy from the RENOIR trial (Abrysvo) was found on PubMed; the only two- and three-season Abrysvo data here are observational (Kaiser Permanente, Veterans Affairs).
No peer-reviewed ConquerRSV (mResvia) second-season efficacy paper was found; the 12-24 month figures come from ACIP's MMWR summary of unpublished manufacturer data.
No RSV adult vaccine efficacy or effectiveness estimate was found for adults aged 50-59 at increased risk (the age band licensed in 2024-2025); only immunogenicity studies surfaced.
No RSV vaccine effectiveness estimate against death as a sole endpoint exists in the cached sources; the closest is critical illness (ICU or death) in rsv-eff-034.
No controlled estimate of long-term lung-function or asthma outcomes after nirsevimab or maternal vaccination (the prevention-trial test of the RSV-asthma hypothesis) was found; the first- and second-year nirsevimab outcome papers were not fetched.
The systematic review of age at RSV hospitalisation and later asthma (PMID 38349900) could not pool its five studies and was not compiled as a record; the post-acute records are single cohorts.
No post-acute record for older adults beyond Guillain-Barre syndrome: cardiovascular events after RSV were only found as in-hospital complications (filed as burden), not as post-discharge hazard ratios against uninfected controls.
RSV is not nationally notifiable in the United States, so the burden figures come from sentinel surveillance (RSV-NET, NVSN) and modelling rather than case counts; the notifiable flag is set to no for all three disease ids and some countries (e.g. parts of Europe) do notify.

Flags for review

The Lancet global-burden records (rsv-bur-001 to 005, 017, 018) carry uncertainty ranges in ci_low/ci_high, not 95% confidence intervals, because the compact format has no separate field. Each notes field says so; the renderer will label them as CIs unless it is told otherwise.
Nirsevimab (rsv-eff-048 to 055) is a monoclonal antibody, not a vaccine. It is filed as efficacy with platform=monoclonal antibody because it is the alternative to maternal RSVpreF for the same infants. Confirm it belongs on the RSV vaccine page and that the page says it is passive immunisation.
Three adult-vaccine trial records report intervals that are not 95% CIs because of alpha-spending (96.95% for rsv-eff-001, 97.5% for rsv-eff-006 to 011, 96.66% for rsv-eff-012 and 013, 95.88% and 96.36% for rsv-eff-015 and 016, 99.5% and 97.58% for rsv-eff-021 to 023). The notes say so; the renderer labels all as 95%.
rsv-eff-019, rsv-eff-020 and rsv-saf-004 resolve to whole MMWR tables (the table is one unbroken sentence to the compiler), so the stored quote is long and the cited row is inside it. The values were verified against the row text by grep before filing. A reviewer should confirm the rendered quote is readable.
Waning is the headline finding across the adult records and must be shown as a curve, not a single number: Arexvy 82.6 (season 1) to 67.2 (two seasons) to 62.9 (three seasons) in the RCT; mResvia 83.7 (median 3.7 months) to 56.1 (to 12 months) to 30.0 (12-24 months); Abrysvo 80 to 70 to 51 percent by season in observational data. ACIP has not set a revaccination interval, and the Arexvy revaccination arm (rsv-eff-008) added nothing.
Immunocompromised adults: rsv-eff-039 (30%, -9 to 55 over two seasons) and rsv-eff-044 (54%, -48 to 85 in season two) have intervals including zero, while rsv-eff-035 and rsv-eff-045 show reasonable first-season protection. These conflict only on time horizon; present them together, not selectively.
GBS after RSV vaccination is product-specific in the US data (rsv-saf-003: excess 18.2 per million for Abrysvo, 5.2 for Arexvy, only Abrysvo significant) and higher in England's Abrysvo programme (rsv-saf-002: 23 per million). Put beside rsv-pa-008 (GBS roughly doubles after RSV disease itself) and the ACIP table of preventable hospitalisations per million doses, which is in the cached MMWR page but not compiled as a record.
Preterm birth after maternal RSVpreF (rsv-saf-004, RR 1.20, 0.99-1.46 in the trial window) is the reason the licence is restricted to 32-36 weeks; the maternal real-world records (rsv-eff-026 to 032) all come from programmes using that restricted window or 28 weeks onward (UK). The GSK maternal candidate was stopped for preterm birth and is not in this file.
Burden denominators differ: rsv-bur-013, 019, 026 to 028 and 030 to 032 are per hospitalised case; rsv-bur-010, 011, 014, 015, 021 to 023 and 033 are per population; rsv-bur-002, 003 are per all-cause death. Do not multiply across them.
The ICU and mortality comparisons with influenza (rsv-bur-030 to 033) use influenza as the comparator, in a largely influenza-vaccinated older population; they say RSV is at least as severe as influenza among the hospitalised, not that RSV causes more deaths overall (Thompson 2003, rsv-bur-034, found influenza caused three times more).
websource.py failed on both MMWR pages under the default Windows console code page ('charmap' codec cannot encode U+2265). Both snapshots were taken with PYTHONUTF8=1; the cached text files are UTF-8. Other agents on Windows will hit the same error on any page containing a non-cp1252 character.

Search log (30 searches)

respiratory syncytial virus infant hospitalization rate month of age · PubMed → Found Li 2022 (35598608), Hall 2013 (23878043), Curns 2024 (38298053), Wang 2024 (38367641), Sun 2023 NMA (36800182); compiled as rsv-bur-001 to 004, 010 to 018.
respiratory syncytial virus global burden children under 5 mortality systematic analysis · PubMed → Found Antillon 2023 (37459352), GBD papers; compiled as rsv-bur-007 and 008.
respiratory syncytial virus older adults hospitalization burden influenza comparison · PubMed → Found Ackerson 2019 (30452608), Widmer 2012 (22529314), Kwon 2017 (29262784); compiled as rsv-bur-030 to 033.
RSVPreF3 OA vaccine efficacy older adults AReSVi-006 · PubMed → Found Papi 2023 (36791160), Ison 2024 (38253338), Ison 2025 (40245915), Feldman 2024 (37698366); compiled as rsv-eff-001 to 011.
RSVpreF bivalent prefusion F vaccine older adults RENOIR efficacy · PubMed → Found Walsh 2023 (37018468); compiled as rsv-eff-012 to 014.
mRNA-1345 RSV vaccine efficacy older adults ConquerRSV · PubMed → Returned immunogenicity papers only; the efficacy paper came from the follow-up search below.
mRNA-1345 vaccine efficacy randomized trial adults 60 years · PubMed → Found Wilson 2023 (38091530); compiled as rsv-eff-015 to 017.
maternal RSVpreF vaccine MATISSE infants efficacy severe lower respiratory tract illness · PubMed → Found Kampmann 2023 (37018474), Simoes 2025 (39746212); compiled as rsv-eff-021 to 025.
nirsevimab efficacy infants MELODY HARMONIE medically attended RSV · PubMed → Returned nothing; split into the two searches below.
nirsevimab MELODY trial · PubMed → Found Hammitt 2022 (35235726), Simoes 2023 pooled (36634694); compiled as rsv-eff-048 to 050.
nirsevimab HARMONIE hospitalisation · PubMed → Found Drysdale 2023 (38157500), Munro 2025 (40379431); compiled as rsv-eff-051 to 053.
RSV vaccine effectiveness older adults real-world test-negative hospitalization 60 years · PubMed → Found Payne 2024 (39426837), Bucholc 2026 (42099879), Tartof 2026 (42758281); compiled as rsv-eff-033 to 035, 042, 043.
RSV vaccine effectiveness 75 years older hospitalization second season · PubMed → Found Surie 2025 (40884491), Bajema 2026 (41284307), Fry 2025 (40343698); compiled as rsv-eff-036 to 041, 045, 046 and rsv-saf-003.
RSV vaccine effectiveness immunocompromised adults · PubMed → Found Tartof 2026 two-season (42256620) and IDSA guideline; compiled as rsv-eff-044.
respiratory syncytial virus infancy recurrent wheeze asthma cohort hazard ratio · PubMed → Found Escobar 2013 (23782528); compiled as rsv-pa-003 to 005.
RSV infection infancy asthma risk cohort hazard ratio · PubMed → Found INSPIRE Rosas-Salazar 2023 (37086744) and Shiroshita 2024 review (38349900); compiled as rsv-pa-006 and 007.
Sigurs respiratory syncytial virus bronchiolitis asthma allergy age 18 · PubMed → Found Sigurs 2010 (20581410); compiled as rsv-pa-001 and 002.
RSV hospitalisation children asthma registry cohort hazard ratio Denmark OR Sweden OR Norway OR Finland · PubMed → Returned unrelated Nordic papers; no registry HR found (see gaps).
maternal RSVpreF vaccine effectiveness infants real-world hospitalization · PubMed → Found Perez Marc 2025 (40339585), McLachlan 2026 (41325764), Williams 2025 (40690922), O'Hagan 2026 (42385756), Batool 2026 meta-analysis (42709454); compiled as rsv-eff-026 to 032.
respiratory syncytial virus older adults mortality hospitalized case fatality · PubMed → Found Nguyen-Van-Tam 2022 (36384703), Scheltema 2017 RSV GOLD (28911764), Bylsma 2022 (35968871); compiled as rsv-bur-009, 020, 029.
respiratory syncytial virus 65 years older incidence hospitalization death United States surveillance RSV-NET · PubMed → Returned nothing directly; RSV-NET papers found via the search below.
RSV ICU admission hospitalized older adults in-hospital mortality · PubMed → Found Havers 2024 (39535791), Woodruff 2024 (38619857); compiled as rsv-bur-021 to 028.
respiratory syncytial virus deaths older adults United States annual estimate excess mortality · PubMed → Found Thompson 2003 (12517228), Byington 2015 (25489019), Prill 2021 death certificates (34754948, not compiled); compiled as rsv-bur-019, 034, 035.
RSV vaccine Guillain-Barre syndrome older adults self-controlled OR cohort · PubMed → Found Stowe 2025 (41381510), Liang 2026 GBS after RSV disease (41234154); compiled as rsv-saf-001, 002 and rsv-pa-008.
nirsevimab real-world effectiveness hospitalization infants systematic review meta-analysis · PubMed → Found Sumsuzzman 2025 (40319903), Lee 2025 living review (40930981), Du 2026 (42339311, not compiled); compiled as rsv-eff-054 and 055.
RSVPreF3 real-world effectiveness hospitalization older adults Europe · PubMed → Found Trusinska 2026 meta-analysis (41767892); compiled as rsv-eff-047.
respiratory syncytial virus hospitalisation children under 5 low-income middle-income in-hospital case fatality ratio · PubMed → Only a metapneumovirus burden paper; recorded as a gap.
RSVpreF RENOIR second season efficacy older adults · PubMed → Nothing found; recorded as a gap.
mRNA-1345 efficacy follow-up 18 months older adults · PubMed → Nothing found on PubMed; the ACIP MMWR page (web cdc-gov-3c3f9926cb) supplied the 12- and 24-month figures.
RSV ACIP recommendations adults 75 years MMWR 2024 · PubMed → Returned a coverage report only; the MMWR recommendation pages were snapshotted directly with websource.py (cdc-gov-3c3f9926cb adults, cdc-gov-5ae3186ae0 maternal).