COVID-19 vaccines — Vaccine Data Navigator

← All vaccines

disease risks

post-acute and long-term sequelae

vaccine efficacy and effectiveness

vaccine safety and adverse events

sources

COVID-19 (acute) SARS-CoV-2

Disease risks

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

Outcome (O)	Population (P)	Comparator	Estimate	Design (S)	Source
Death from SARS-CoV-2 infection (infection fatality rate) severity: death case definition: Infection fatality rate from seroprevalence studies with reported fatalities 4 weeks after the study midpoint	age 10 (age-specific estimate from the meta-regression) vaccination status: unvaccinated country: 34 geographical locations, mostly high-income setting: community seroprevalence period: pre-vaccine era, studies published before 18 September 2020 n: 27 studies 5-11y		0.002 IFR (%) per infection	meta-analysis	Levin et al. 2020 Eur J Epidemiol quote The estimated age-specific IFR is very low for children and younger adults (e.g., 0.002% at age 10 and 0.01% at age 25) but increases progressively to 0.4% at age 55, 1.4% at age 65, 4.6% at age 75, and 15% at age 85. abstract, results Pre-vaccine, ancestral-strain era. The same sentence gives IFRs for other ages; separate records cover ages 65 and 85. Modelled exponential age relationship, no CI reported for the age-specific points in the abstract.
Death from SARS-CoV-2 infection (infection fatality rate) severity: death case definition: Infection fatality rate from seroprevalence studies with reported fatalities 4 weeks after the study midpoint	age 65 (age-specific estimate from the meta-regression) vaccination status: unvaccinated country: 34 geographical locations, mostly high-income setting: community seroprevalence period: pre-vaccine era, studies published before 18 September 2020 n: 27 studies 65+		1.4 IFR (%) per infection	meta-analysis	Levin et al. 2020 Eur J Epidemiol quote The estimated age-specific IFR is very low for children and younger adults (e.g., 0.002% at age 10 and 0.01% at age 25) but increases progressively to 0.4% at age 55, 1.4% at age 65, 4.6% at age 75, and 15% at age 85. abstract, results Pre-vaccine, ancestral-strain era. Infection fatality, not case fatality: the denominator is all infections estimated from serology, so this is far lower than the hospital-based CFRs in this file.
Death from SARS-CoV-2 infection (infection fatality rate) severity: death case definition: Infection fatality rate from seroprevalence studies with reported fatalities 4 weeks after the study midpoint	age 85 (age-specific estimate from the meta-regression) vaccination status: unvaccinated country: 34 geographical locations, mostly high-income setting: community seroprevalence period: pre-vaccine era, studies published before 18 September 2020 n: 27 studies 65+		15 IFR (%) per infection	meta-analysis	Levin et al. 2020 Eur J Epidemiol quote The estimated age-specific IFR is very low for children and younger adults (e.g., 0.002% at age 10 and 0.01% at age 25) but increases progressively to 0.4% at age 55, 1.4% at age 65, 4.6% at age 75, and 15% at age 85. abstract, results Pre-vaccine, ancestral-strain era. The steep age gradient (several thousand-fold between age ten and age eighty-five in the same model) is the central fact of acute burden for this disease.
Death from SARS-CoV-2 infection (population infection fatality rate) severity: death case definition: IFR from representative serology studies with Bayesian correction for assay characteristics and seroreversion	all ages (population IFR) vaccination status: unvaccinated country: developing countries (LMIC) setting: community seroprevalence period: serology collected by February 2021, pre-vaccine era All ages		0.5 IFR (%) per infection	meta-analysis	Levin et al. 2022 BMJ Glob Health quote The median value of the population IFR was about 0.5%, similar to that of high-income countries, because disparities in healthcare access were roughly offset by differences in population age structure. abstract, RESULTS Age-specific IFRs in developing countries were roughly double those of high-income countries in the same review, but younger populations offset this so the population IFR is similar. LMIC comparison record.
Death among hospitalised COVID-19 patients (case fatality rate) severity: death case definition: CFR as reported by the included primary studies	all ages as included in the primary studies vaccination status: unvaccinated country: multiple setting: hospital period: 2020 (pre-vaccine era, studies published through 2020) All ages		13.0 (9.0–17.0) CFR (%) per hospitalised case	meta-analysis	Alimohamadi et al. 2021 J Prev Med Hyg quote The pooled CFR of COVID-19 in general population was 1.0% (95% CI: 1.0-3.0); P < 0.001; I2 = 94.3), while in hospitalized patients was 13.0% (95% CI: 9.0-17.0); P < 0.001, I2 = 95.6). abstract, RESULTS Denominator is hospitalised cases, not all infections; do not place beside the serology-based IFR without labelling. Extreme heterogeneity between studies. Pre-vaccine, early-pandemic ascertainment.
Death among reported COVID-19 cases, Delta variant period (case fatality rate) severity: death strain: Delta case definition: CFR among reported cases during variant-of-concern epidemic periods	all ages vaccination status: mixed country: multiple continents setting: surveillance period: Delta epidemic period, studies published 2020 to March 2023 All ages		2.01 CFR (%) per reported case	meta-analysis	Xia et al. 2024 Int J Infect Dis quote RESULTS: There were variations in the CFRs among different variants of COVID-19 (Alpha: 2.62%, Beta: 4.19%, Gamma: 3.60%, Delta: 2.01%, Omicron: 0.70%), and disparities in CFRs also existed among continents. abstract, RESULTS CFR among reported cases depends on testing capacity, age structure and vaccination coverage, all of which the review found associated with CFR. Vaccination status is mixed and not separated. No CI in the abstract.
Death among reported COVID-19 cases, Omicron variant period (case fatality rate) severity: death strain: Omicron case definition: CFR among reported cases during variant-of-concern epidemic periods	all ages vaccination status: mixed country: multiple continents setting: surveillance period: Omicron epidemic period, studies published 2020 to March 2023 All ages		0.70 CFR (%) per reported case	meta-analysis	Xia et al. 2024 Int J Infect Dis quote RESULTS: There were variations in the CFRs among different variants of COVID-19 (Alpha: 2.62%, Beta: 4.19%, Gamma: 3.60%, Delta: 2.01%, Omicron: 0.70%), and disparities in CFRs also existed among continents. abstract, RESULTS The Omicron-era CFR is a mix of lower intrinsic severity, prior immunity from vaccination and infection, and wider testing; the review cannot separate these. No CI in the abstract.
Death within 28 days of a positive SARS-CoV-2 test in clinical risk groups severity: death strain: Delta variant period case definition: Standardised case fatality rate within 28 days of a positive virology test, linked to death registry	all ages in the sentinel primary care network risk group: clinical risk groups (conditions placing people at increased risk of critical disease) vaccination status: mixed country: England setting: primary care sentinel network, linked data period: Delta-dominant period, 2021 All ages	vs people not in clinical risk groups (same sentence)	12.8 case fatality rate per 1,000 positive tests within 28 days per 1,000 positive tests	cohort	Whitaker et al. 2023 J Infect quote The standardised case fatality rate within 28 days of a positive test was 3.9/1000 in people not in risk groups, compared to 12.8/1000 in clinical risk groups. abstract, FINDINGS The same sentence gives the much lower rate for people not in risk groups. Mixed vaccination status in a period of high adult coverage, so this is a current-era, not pre-vaccine, figure.
COVID-19-associated death, unvaccinated versus fully vaccinated and boosted adults severity: death strain: Delta predominance case definition: Death reported to jurisdictional surveillance, age-standardised incidence rate ratio	adults 18 years and older vaccination status: unvaccinated country: United States, 25 jurisdictions setting: surveillance period: October-November 2021 18-49y50-64y65+	vs fully vaccinated adults who received booster doses	53.2 incidence rate ratio for COVID-19-associated death, unvaccinated vs fully vaccinated with booster per population by vaccination status	surveillance	Johnson et al. 2022 MMWR Morb Mortal Wkly Rep quote During October-November, unvaccinated persons had 13.9 and 53.2 times the risks for infection and COVID-19-associated death, respectively, compared with fully vaccinated persons who received booster doses, and 4.0 and 12.7 times the risks compared with fully vaccinated persons without booster doses. abstract Age-standardised but otherwise unadjusted surveillance rate ratio; healthy-vaccinee and testing-behaviour differences can inflate it. The same sentence gives the lower ratio versus fully vaccinated adults without boosters.
COVID-19-associated hospitalisation, peak weekly rate severity: hospitalisation strain: Omicron (BA.1) predominance case definition: Laboratory-confirmed SARS-CoV-2 in a hospitalised resident of the COVID-NET catchment	adults 18 years and older vaccination status: mixed country: United States, 14 states (COVID-NET) setting: population-based hospital surveillance period: December 19, 2021 to January 31, 2022 18-49y50-64y65+		38.4 peak weekly hospitalisations per 100,000 adults per 100,000 adults per week	surveillance	Taylor et al. 2022 MMWR Morb Mortal Wkly Rep quote During the Omicron-predominant period, weekly COVID-19-associated hospitalization rates (hospitalizations per 100,000 adults) peaked at 38.4, compared with 15.5 during Delta predominance. abstract A peak weekly rate, not an annual or cumulative rate. The same sentence gives the lower Delta-period peak. The abstract also reports unvaccinated adults hospitalised at many times the rate of boosted adults in the same period.
COVID-19-associated hospitalisation in children and adolescents, peak weekly rate severity: hospitalisation strain: Omicron (BA.1) predominance case definition: Laboratory-confirmed SARS-CoV-2 in a hospitalised resident aged 0-17 years of the COVID-NET catchment	children and adolescents 0-17 years vaccination status: mixed country: United States, 14 states (COVID-NET) setting: population-based hospital surveillance period: week ending January 8, 2022 Infant <1y1-4y5-11y12-17y		7.1 peak weekly hospitalisations per 100,000 children and adolescents per 100,000 children and adolescents per week	surveillance	Marks et al. 2022 MMWR Morb Mortal Wkly Rep quote The Omicron variant peak (7.1 per 100,000) was four times that of the Delta variant peak (1.8), with the largest increase observed among children aged 0-4 years.¶ During December 2021, the monthly hospitalization rate among unvaccinated adolescents aged 12-17 years (23.5) was six times that among fully vaccinated adolescents (3.8). abstract Peak weekly rate during Omicron, several times the Delta-period peak given in the same sentence; the largest increase was in children under five, who were not yet vaccine-eligible.
COVID-19-associated hospitalisation in unvaccinated children 5-11 years, cumulative rate severity: hospitalisation strain: Omicron (BA.1) predominance case definition: Laboratory-confirmed SARS-CoV-2 in a hospitalised child aged 5-11 years in the COVID-NET catchment	children 5-11 years vaccination status: unvaccinated country: United States, 14 states (COVID-NET) setting: population-based hospital surveillance period: December 19, 2021 to February 28, 2022 5-11y	vs vaccinated children 5-11 years, same period	19.1 cumulative hospitalisations per 100,000 population per 100,000 unvaccinated children	surveillance	Shi et al. 2022 MMWR Morb Mortal Wkly Rep quote The cumulative hospitalization rate during the Omicron-predominant period was 2.1 times as high among unvaccinated children (19.1 per 100,000 population) as among vaccinated¶ children (9.2).** Non-Hispanic Black (Black) children accounted for the largest proportion of unvaccinated children (34%) and represented approximately one third of COVID-19-associated hospitalizations in this age group. abstract The abstract also reports that about a fifth of the hospitalised children in this period were admitted to intensive care and nearly a third had no underlying condition. Unadjusted surveillance comparison by vaccination status.
COVID-19-associated hospitalisation in infants under 6 months, annual rate severity: hospitalisation strain: Omicron JN.1-era lineages case definition: COVID-19-associated hospitalisations among children in the United States (national estimate)	infants under 6 months vaccination status: unvaccinated country: United States setting: population-based surveillance period: September 2023 to August 2024 Infant <1y		600 hospitalisations per 100,000 children per year per 100,000 infants under 6 months	surveillance	Irving et al. 2025 MMWR Morb Mortal Wkly Rep quote During September 2023-August 2024, approximately 38,000 COVID-19-associated hospitalizations occurred among children and adolescents aged <18 years in the United States, a rate of approximately 53 per 100,000 children, ranging from 600 per 100,000 children aged <6 months to 21 per 100,000 children and adolescents aged 5-17 years. abstract, background Infants under six months are too young for vaccination; this rate is the burden maternal vaccination is meant to address. The same sentence gives the far lower rate for ages five to seventeen.

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
Confirmed symptomatic COVID-19 severity: symptomatic strain: pre-variant-of-concern era case definition: Confirmed symptomatic COVID-19 as defined in the included RCT	18 years or older country: as enrolled in the included trial period: trials to November 2021 n: 25,463 participants in 1 RCT 18-49y50-64y65+	BBIBP-CorV (Sinopharm-Beijing) platform: inactivated whole virus doses: 2 vs placebo	78.10 (64.80–86.30) VE (%)	systematic review GRADE: high 1 RCT	Graña et al. 2022 Cochrane Database Syst Rev quote Confirmed symptomatic COVID-19 High-certainty evidence found that BNT162b2 (BioNtech/Fosun Pharma/Pfizer), mRNA-1273 (ModernaTx), ChAdOx1 (Oxford/AstraZeneca), Ad26.COV2.S, BBIBP-CorV (Sinopharm-Beijing), and BBV152 (Bharat Biotect) reduce the incidence of symptomatic COVID-19 compared to placebo (vaccine efficacy (VE): BNT162b2: 97.84%, 95% CI 44.25% to 99.92%; 2 RCTs, 44,077 participants; mRNA-1273: 93.20%, 95% CI 91.06% to 94.83%; 2 RCTs, 31,632 participants; ChAdOx1: 70.23%, 95% CI 62.10% to 76.62%; 2 RCTs, 43,390 participants; Ad26.COV2.S: 66.90%, 95% CI 59.10% to 73.40%; 1 RCT, 39,058 participants; BBIBP-CorV: 78.10%, 95% CI 64.80% to 86.30%; 1 RCT, 25,463 participants; BBV152: 77.80%, 95% CI 65.20% to 86.40%; 1 RCT, 16,973 participants). abstract, MAIN RESULTS, confirmed symptomatic COVID-19 Inactivated-platform record from the Cochrane review, which rated the symptomatic-disease evidence for this product high certainty. The same sentence gives the mRNA, adenovirus and BBV152 trial estimates; the review notes the trials pre-date variants of concern and excluded pregnant, previously infected and immunocompromised people.
All-cause mortality severity: death case definition: All-cause death in the trial population	adults country: multinational period: trial follow-up to November 2021 n: 43,783 participants in 1 RCT 18-49y50-64y65+	Ad26.COV2.S (Janssen) platform: adenovirus vector doses: 1 vs placebo	0.25 (0.09–0.67) risk ratio for all-cause mortality	systematic review GRADE: high 1 RCT	Graña et al. 2022 Cochrane Database Syst Rev quote The evidence for mortality was generally sparse and of low or very low certainty for all WHO-approved vaccines, except AD26.COV2.S (Janssen), which probably reduces the risk of all-cause mortality (risk ratio (RR) 0.25, 95% CI 0.09 to 0.67; 1 RCT, 43,783 participants; high-certainty evidence). abstract, MAIN RESULTS, mortality The only vaccine for which the Cochrane review found high-certainty evidence on all-cause mortality; for the other vaccines the mortality evidence was sparse and of low or very low certainty, which is an absence of data, not evidence of no effect.
SARS-CoV-2 Omicron infection (PCR or antigen confirmed) severity: any infection strain: Omicron case definition: PCR-confirmed or antigen-test confirmed infection	5-11 years country: multiple period: studies to January 23, 2023 5-11y	BNT162b2 or mRNA-1273 (EMA-approved paediatric mRNA vaccines) platform: mRNA doses: 2 vs unvaccinated children	41.6 (28.1–52.6) VE (%)	meta-analysis GRADE: low 8 non-randomised studies	Piechotta et al. 2023 Lancet Child Adolesc Health quote Vaccine effectiveness after two doses against omicron infections was 41·6% (95% CI 28·1-52·6; eight non-randomised studies of interventions [NRSIs]; CoE low), 36·2% (21·5-48·2; six NRSIs; CoE low) against symptomatic COVID-19, 75·3% (68·0-81·0; six NRSIs; CoE moderate) against COVID-19-related hospitalisations, and 78% (48-90, one NRSI; CoE very low) against MIS-C. abstract, FINDINGS Moderate protection against Omicron infection in young children; the same sentence gives higher VE against hospitalisation and a separate record carries it. Low certainty, non-randomised evidence.
COVID-19-related hospitalisation severity: hospitalisation strain: Omicron case definition: Hospital admission due to COVID-19 as defined by the included studies	5-11 years country: multiple period: studies to January 23, 2023 5-11y	BNT162b2 or mRNA-1273 (EMA-approved paediatric mRNA vaccines) platform: mRNA doses: 2 vs unvaccinated children	75.3 (68.0–81.0) VE (%)	meta-analysis GRADE: moderate 6 non-randomised studies	Piechotta et al. 2023 Lancet Child Adolesc Health quote Vaccine effectiveness after two doses against omicron infections was 41·6% (95% CI 28·1-52·6; eight non-randomised studies of interventions [NRSIs]; CoE low), 36·2% (21·5-48·2; six NRSIs; CoE low) against symptomatic COVID-19, 75·3% (68·0-81·0; six NRSIs; CoE moderate) against COVID-19-related hospitalisations, and 78% (48-90, one NRSI; CoE very low) against MIS-C. abstract, FINDINGS Moderate-certainty protection against hospitalisation in children aged five to eleven. The review could not estimate VE against death because deaths in unvaccinated children were below one per hundred thousand and none were reported in vaccinated children.
RT-PCR confirmed SARS-CoV-2 infection in pregnancy severity: any confirmed infection strain: pre-Omicron era (studies to early 2022) case definition: RT-PCR confirmed SARS-CoV-2 infection	pregnant people pregnancy: pregnant country: multiple period: studies to early 2022 n: 18,828 vaccinated pregnant people 18-49y	mRNA COVID-19 vaccines platform: mRNA doses: 2 time since vaccination: 7 days after dose 2 vs unvaccinated pregnant people	89.5 (69.0–96.4) VE (%)	meta-analysis	Prasad et al. 2022 Nat Commun quote We show that the effectiveness of mRNA vaccination against RT-PCR confirmed SARS-CoV-2 infection 7 days after second dose was 89·5% (95% CI 69·0-96·4%, 18,828 vaccinated pregnant people, I2 = 73·9%). abstract Pooled from observational studies with high heterogeneity. The same review found stillbirth lower in the vaccinated cohort and no excess of other adverse perinatal outcomes, which belongs on the safety side, not here.
Hospital admission or severe disease from Omicron infection severity: hospitalisation or severe disease strain: Omicron case definition: Hospital admission or severe disease as defined in the included studies	all ages as included prior infection: previous SARS-CoV-2 infection (hybrid immunity) country: multiple period: studies January 2020 to June 2022 All ages	any COVID-19 vaccine, primary series, combined with prior infection (hybrid immunity) platform: mixed doses: primary series time since vaccination: 12 months after the most recent infection or vaccination vs as defined in the included studies (no prior infection and unvaccinated, or as reported); many estimates at serious risk of bias	97.4 (91.4–99.2) protective effectiveness (%) from log-odds meta-regression	meta-analysis	Bobrovitz et al. 2023 Lancet Infect Dis quote The effectiveness of hybrid immunity against hospital admission or severe disease was 97·4% (95% CI 91·4-99·2) at 12 months with primary series vaccination and 95·3% (81·9-98·9) at 6 months with the first booster vaccination after the most recent infection or vaccination. abstract, FINDINGS Hybrid immunity (infection plus vaccination) gave the highest and most durable protection against severe disease. The same abstract reports previous infection alone protected less against severe disease and that all estimates against reinfection waned within months. The abstract's estimates against reinfection were not compiled; protection against reinfection waned to under half by a year.
Laboratory-confirmed symptomatic Covid-19 with onset at least 7 days after dose 2 severity: symptomatic strain: ancestral (pre-variant era) case definition: Laboratory-confirmed Covid-19 per trial protocol	16 years of age or older prior infection: no evidence of prior infection (primary analysis) country: multinational period: 2020, pivotal trial n: 43,448 injected participants 12-17y18-49y50-64y65+	BNT162b2 (Pfizer-BioNTech) platform: mRNA doses: 2 schedule: 21 days apart time since vaccination: at least 7 days after dose 2, median 2 months follow-up vs placebo	95 (90.3–97.6) VE (%)	RCT	Polack et al. 2020 N Engl J Med quote There were 8 cases of Covid-19 with onset at least 7 days after the second dose among participants assigned to receive BNT162b2 and 162 cases among those assigned to placebo; BNT162b2 was 95% effective in preventing Covid-19 (95% credible interval, 90.3 to 97.6). abstract, RESULTS The interval is a Bayesian credible interval, as the source states. Pre-variant era, short follow-up; the six-month report from the same trial shows gradual decline.
Laboratory-confirmed symptomatic Covid-19 through 6 months severity: symptomatic strain: ancestral, Alpha and Beta era case definition: Laboratory-confirmed Covid-19 per trial protocol	16 years of age or older (plus 12 to 15 year cohort) prior infection: no evidence of previous SARS-CoV-2 infection country: multinational period: through 6 months of follow-up, 2020-2021 n: 44,165 participants 16 and older and 2264 aged 12 to 15 12-17y18-49y50-64y65+	BNT162b2 (Pfizer-BioNTech) platform: mRNA doses: 2 schedule: 21 days apart time since vaccination: through 6 months after vaccination vs placebo	91.3 (89.0–93.2) VE (%)	RCT	Thomas et al. 2021 N Engl J Med quote Vaccine efficacy against Covid-19 was 91.3% (95% confidence interval [CI], 89.0 to 93.2) through 6 months of follow-up among the participants without evidence of previous SARS-CoV-2 infection who could be evaluated. abstract, RESULTS The abstract states there was a gradual decline in efficacy over the six months; this is the average over the period, not the end-of-period value.
Symptomatic Covid-19 with onset at least 14 days after dose 2 severity: symptomatic strain: ancestral (pre-variant era) case definition: Symptomatic Covid-19 confirmed per trial protocol	adults at high risk for SARS-CoV-2 infection or its complications prior infection: not previously infected country: United States, 99 centres period: 2020, pivotal trial n: 30,420 participants 18-49y50-64y65+	mRNA-1273 (Moderna) platform: mRNA doses: 2 schedule: 28 days apart time since vaccination: at least 14 days after dose 2 vs placebo	94.1 (89.3–96.8) VE (%)	RCT	Baden et al. 2021 N Engl J Med quote Symptomatic Covid-19 illness was confirmed in 185 participants in the placebo group (56.5 per 1000 person-years; 95% confidence interval [CI], 48.7 to 65.3) and in 11 participants in the mRNA-1273 group (3.3 per 1000 person-years; 95% CI, 1.7 to 6.0); vaccine efficacy was 94.1% (95% CI, 89.3 to 96.8%; P<0.001). abstract, RESULTS All severe cases in this interim analysis were in the placebo group. Efficacy was reported as similar in participants aged sixty-five and older.
Severe Covid-19 per trial definition severity: severe strain: ancestral and early-variant era case definition: Severe Covid-19 per trial protocol	adults at high risk for Covid-19 or its complications prior infection: not previously infected country: United States, 99 centres period: blinded phase to March 26, 2021, median follow-up 5.3 months n: 30,415 participants 18-49y50-64y65+	mRNA-1273 (Moderna) platform: mRNA doses: 2 schedule: 28 days apart time since vaccination: at least 14 days after dose 2, median 5.3 months vs placebo	98.2 (92.8–99.6) VE (%)	RCT	El et al. 2021 N Engl J Med quote The efficacy in preventing severe disease was 98.2% (95% CI, 92.8 to 99.6), with 2 cases in the mRNA-1273 group and 106 in the placebo group, and the efficacy in preventing asymptomatic infection starting 14 days after the second injection was 63.0% (95% CI, 56.6 to 68.5), with 214 cases in the mRNA-1273 group and 498 in the placebo group. abstract, RESULTS Final blinded-phase analysis. The same sentence gives much lower efficacy against asymptomatic infection, showing the severity gradient in protection.
Moderate to severe-critical Covid-19 with onset at least 14 days after vaccination severity: moderate to severe-critical strain: ancestral and Beta (20H/501Y.V2 in South Africa) case definition: Moderate to severe-critical Covid-19 per trial protocol	adults prior infection: SARS-CoV-2 negative at baseline (per-protocol) country: international, including United States, Latin America and South Africa period: 2020-2021, pivotal trial n: 39,321 per-protocol participants 18-49y50-64y65+	Ad26.COV2.S (Janssen) platform: adenovirus vector doses: 1 time since vaccination: at least 14 days after the single dose vs placebo	66.9 (59.0–73.4) VE (%)	RCT	Sadoff et al. 2021 N Engl J Med quote 348 in the placebo group; efficacy, 66.9%; adjusted 95% confidence interval [CI], 59.0 to 73.4) and at least 28 days after administration (66 vs. abstract, RESULTS Single-dose adenovirus-vector vaccine, so not directly comparable to two-dose mRNA figures. Efficacy was higher against severe-critical disease and lower in South Africa where the Beta variant dominated, both in the same abstract. The copied sentence is a fragment because the cache splits on the abbreviation vs. inside the parenthesis.
Symptomatic COVID-19 more than 14 days after dose 2 (NAAT-positive) severity: symptomatic strain: ancestral (2020) case definition: Symptomatic COVID-19 with a nucleic acid amplification test-positive swab in seronegative participants	18 years and older prior infection: seronegative at baseline country: United Kingdom and Brazil (interim efficacy analysis) period: April 23 to November 4, 2020 n: 8895 participants in the SD/SD cohort 18-49y50-64y65+	ChAdOx1 nCoV-19 (AZD1222, Oxford-AstraZeneca) platform: adenovirus vector doses: 2 schedule: two standard doses time since vaccination: more than 14 days after dose 2 vs control (MenACWY conjugate vaccine or saline)	62.1 (41.0–75.7) VE (%)	RCT	Voysey et al. 2021 Lancet quote In participants who received two standard doses, vaccine efficacy was 62·1% (95% CI 41·0-75·7; 27 [0·6%] of 4440 in the ChAdOx1 nCoV-19 group vs71 [1·6%] of 4455 in the control group) and in participants who received a low dose followed by a standard dose, efficacy was 90·0% (67·4-97·0; three [0·2%] of 1367 vs 30 [2·2%] of 1374; pinteraction=0·010). abstract, FINDINGS The low-dose/standard-dose subgroup in the same sentence had higher efficacy, an unplanned finding the authors flagged. All hospitalised cases arising from three weeks after the first dose were in the control arm.
Virologically confirmed symptomatic COVID-19 from 7 days after dose 2 severity: symptomatic strain: ancestral and Alpha era (United Kingdom) case definition: Virologically confirmed mild, moderate or severe COVID-19	18-84 years country: United Kingdom period: placebo-controlled phase, maximum 7.5 months (median 4.5) post-vaccination, 2020-2021 n: 13,989 per-protocol participants 18-49y50-64y65+	NVX-CoV2373 (Novavax) platform: recombinant protein (adjuvanted) doses: 2 time since vaccination: 7 days after dose 2 through a median of 4.5 months vs placebo	82.7 (73.3–88.8) VE (%)	RCT	Heath et al. 2023 Clin Infect Dis quote At a maximum of 7.5 months (median, 4.5) postvaccination, there were 24 cases of COVID-19 among NVX-CoV2373 recipients and 134 cases among placebo recipients, a vaccine efficacy of 82.7% (95% confidence interval [CI], 73.3%-88.8%). abstract, RESULTS Protein-subunit platform. The same abstract reports efficacy against severe disease with a very wide interval and notes a gradual decrease of protection suggesting a booster.
Covid-19 (symptomatic, per trial definition) severity: symptomatic strain: Omicron (B.1.1.529) predominant case definition: Symptomatic Covid-19 per trial case definition	6 to 23 months country: United States and Canada (KidCOVE) period: 2022, median follow-up 68 days after dose 2 n: 1762 vaccinated and 593 placebo children 6-23 months Infant <1y1-4y	mRNA-1273 (Moderna), 25 microgram paediatric dose platform: mRNA doses: 2 schedule: 28 days apart time since vaccination: median 68 days after dose 2 vs placebo	50.6 (21.4–68.6) VE (%)	RCT	Anderson et al. 2022 N Engl J Med quote The estimated vaccine efficacy against Covid-19 was 36.8% (95% CI, 12.5 to 54.0) among 2-to-5-year-olds and 50.6% (95% CI, 21.4 to 68.6) among 6-to-23-month-olds, at a time when B.1.1.529 (omicron) was the predominant circulating variant. abstract, RESULTS Youngest licensed age group, randomised, Omicron era. The same sentence gives the lower estimate for two-to-five-year-olds. Primary objectives were safety and immunobridging; efficacy was a secondary objective with short follow-up and wide intervals.
Symptomatic COVID-19 caused by the Omicron variant severity: symptomatic strain: Omicron (B.1.1.529, BA.1) case definition: PCR-confirmed symptomatic infection with sequenced or S-gene-target-failure-assigned Omicron	all vaccine-eligible ages in England country: England period: November 27, 2021 to January 12, 2022 n: 886,774 Omicron cases and 1,572,621 test-negative controls 12-17y18-49y50-64y65+	BNT162b2 (Pfizer-BioNTech) platform: mRNA doses: 2 time since vaccination: 2 to 4 weeks after dose 2 vs unvaccinated test-negative controls	65.5 (63.9–67.0) VE (%)	test-negative	Andrews et al. 2022 N Engl J Med quote No effect against the omicron variant was noted from 20 weeks after two ChAdOx1 nCoV-19 doses, whereas vaccine effectiveness after two BNT162b2 doses was 65.5% (95% confidence interval [CI], 63.9 to 67.0) at 2 to 4 weeks, dropping to 8.8% (95% CI, 7.0 to 10.5) at 25 or more weeks. abstract, RESULTS Peak two-dose protection against Omicron symptomatic disease; the same sentence shows it falling to near zero by twenty-five weeks, and no effect from twenty weeks after two ChAdOx1 doses. Against Delta the same study found higher VE at every time point.
Symptomatic COVID-19 caused by the Omicron variant severity: symptomatic strain: Omicron (B.1.1.529, BA.1) case definition: PCR-confirmed symptomatic infection with sequenced or S-gene-target-failure-assigned Omicron	all vaccine-eligible ages in England country: England period: November 27, 2021 to January 12, 2022 12-17y18-49y50-64y65+	BNT162b2 (Pfizer-BioNTech) platform: mRNA doses: 2 time since vaccination: 25 or more weeks after dose 2 vs unvaccinated test-negative controls	8.8 (7.0–10.5) VE (%)	test-negative	Andrews et al. 2022 N Engl J Med quote No effect against the omicron variant was noted from 20 weeks after two ChAdOx1 nCoV-19 doses, whereas vaccine effectiveness after two BNT162b2 doses was 65.5% (95% confidence interval [CI], 63.9 to 67.0) at 2 to 4 weeks, dropping to 8.8% (95% CI, 7.0 to 10.5) at 25 or more weeks. abstract, RESULTS Waning record: two mRNA doses gave almost no protection against symptomatic Omicron infection after six months. Protection against severe disease, not estimated here, waned less in other studies in this file.
Any SARS-CoV-2 Delta infection (symptomatic or asymptomatic) severity: any infection strain: Delta (B.1.617.2) case definition: PCR-confirmed Delta infection, any symptoms	Qatar population, all vaccinated ages country: Qatar period: 2021 Delta wave 12-17y18-49y50-64y65+	BNT162b2 (Pfizer-BioNTech) platform: mRNA doses: 2 time since vaccination: 14 or more days after dose 2 (half of recipients vaccinated several months earlier) vs unvaccinated matched test-negative controls	51.9 (47.0–56.4) VE (%)	test-negative	Tang et al. 2021 Nat Med quote BNT162b2 effectiveness against any, symptomatic or asymptomatic, Delta infection was 45.3% (95% CI, 22.0-61.6%) ≥14 d after the first vaccine dose, but only 51.9% (95% CI, 47.0-56.4%) ≥14 d after the second dose, with 50% of fully vaccinated individuals receiving their second dose before 11 May 2021. abstract Lower than expected for Delta partly because many second doses were months old; the same sentence gives the Moderna mRNA vaccine's effectiveness, which was higher. The severe-disease record from the same study follows.
Severe, critical or fatal COVID-19 from Delta infection severity: severe, critical or fatal strain: Delta (B.1.617.2) case definition: WHO-defined severe, critical or fatal COVID-19 with Delta infection	Qatar population, all vaccinated ages country: Qatar period: 2021 Delta wave 12-17y18-49y50-64y65+	BNT162b2 (Pfizer-BioNTech) platform: mRNA doses: 2 time since vaccination: 14 or more days after dose 2 vs unvaccinated matched test-negative controls	93.4 (85.4–97.0) VE (%)	test-negative	Tang et al. 2021 Nat Med quote Notably, effectiveness against Delta-induced severe, critical or fatal disease was 93.4% (95% CI, 85.4-97.0%) for BNT162b2 and 96.1% (95% CI, 71.6-99.5%) for mRNA-1273 ≥ 14 d after the second dose. abstract The severity gradient: the same vaccine, same population and same period gave only about half protection against any infection but high protection against severe disease.
SARS-CoV-2 infection (any PCR-confirmed) with the Omicron variant severity: any infection strain: Omicron case definition: PCR-confirmed infection in national registries	60 years or above prior infection: previously uninfected residents country: Denmark period: December 21, 2021 to January 31, 2022 50-64y65+	BNT162b2 or mRNA-1273 platform: mRNA doses: 2 time since vaccination: 14 to 30 days after dose 2 vs unvaccinated residents (time-varying exposure, adjusted for age, sex, comorbidity, region)	39.9 (26.3–50.9) VE (%) = 1 - HR x 100	cohort	Gram et al. 2022 PLoS Med quote In the oldest age group, VE against infection after 2 doses was 90.7% (95% CI: 88.2; 92.7) for the Alpha variant, 82.3% (95% CI: 75.5; 87.2) for the Delta variant, and 39.9% (95% CI: 26.3; 50.9) for the Omicron variant 14 to 30 days since vaccination. abstract, METHODS AND FINDINGS Older adults, early after two doses: the same sentence gives much higher two-dose VE for Alpha and Delta in the same age group, so the drop is variant-driven. Non-randomised comparison with unvaccinated people, as the authors note.
SARS-CoV-2 infection (any PCR-confirmed) with the Omicron variant severity: any infection strain: Omicron case definition: PCR-confirmed infection in national registries	60 years or above prior infection: previously uninfected residents country: Denmark period: December 21, 2021 to January 31, 2022 50-64y65+	BNT162b2 or mRNA-1273 platform: mRNA doses: 2 time since vaccination: more than 120 days after dose 2 vs unvaccinated residents (time-varying exposure, adjusted)	4.4 (-0.1–8.7) VE (%) = 1 - HR x 100	cohort	Gram et al. 2022 PLoS Med quote The VE waned over time and was 73.2% (Alpha, 95% CI: 57.1; 83.3), 50.0% (Delta, 95% CI: 46.7; 53.0), and 4.4% (Omicron, 95% CI: -0.1; 8.7) >120 days since vaccination. abstract, METHODS AND FINDINGS Null result: two mRNA doses given more than four months earlier gave essentially no protection against Omicron infection in people aged sixty and over. Protection against hospitalisation in the same study stayed high, which is why this record must be read with the hospitalisation statement in the abstract.
SARS-CoV-2 infection (any PCR-confirmed) with the Omicron variant severity: any infection strain: Omicron case definition: PCR-confirmed infection in national registries	60 years or above prior infection: previously uninfected residents country: Denmark period: December 21, 2021 to January 31, 2022 50-64y65+	BNT162b2 or mRNA-1273 platform: mRNA doses: 3 time since vaccination: 14 to 30 days after dose 3 vs unvaccinated residents (time-varying exposure, adjusted)	57.7 (55.9–59.5) VE (%) = 1 - HR x 100	cohort	Gram et al. 2022 PLoS Med quote Higher estimates were observed after the third dose with VE estimates against infection of 86.1% (Delta, 95% CI: 83.3; 88.4) and 57.7% (Omicron, 95% CI: 55.9; 59.5) 14 to 30 days since vaccination. abstract, METHODS AND FINDINGS Third dose raised early protection against Omicron infection in older adults well above the two-dose figure and, per the abstract, sustained high protection against hospitalisation in this age group.
COVID-19-associated hospitalisation severity: hospitalisation strain: Omicron BA.4/BA.5 era case definition: Hospitalised with laboratory-confirmed COVID-19, IVY Network	65 years and older immune status: immunocompetent country: United States, 18 states period: September 8 to November 30, 2022 65+	bivalent (ancestral + BA.4/BA.5) mRNA booster after at least 2 monovalent doses platform: mRNA doses: 3 or more (bivalent booster after 2 or more monovalent doses) time since vaccination: 7 or more days after the bivalent dose, median 29 days vs unvaccinated	84 VE (%)	test-negative	Surie et al. 2022 MMWR Morb Mortal Wkly Rep quote When compared with unvaccinated persons, VE of a bivalent booster dose received ≥7 days before illness onset (median = 29 days) against COVID-19-associated hospitalization was 84%. abstract Early, short-interval estimate with no CI in the abstract. The same abstract gives a lower relative VE versus people with monovalent doses only, which is the incremental benefit of the booster itself.
COVID-19-related hospitalisation severity: hospitalisation strain: Omicron BA.2.86/JN.1 case definition: COVID-19 hospitalisation in linked electronic health records	80 years and older country: Belgium, Denmark, Italy, Navarre (Spain), Norway, Portugal, Sweden period: December 2023 to February 25, 2024 65+	monovalent XBB.1.5 COVID-19 vaccine (autumn 2023) platform: mRNA (predominantly) doses: 1 updated dose on top of prior doses time since vaccination: 14 or more days after the autumn 2023 dose vs not vaccinated in autumn 2023	41 (35–46) VE (%) = (1 - pooled aHR) x 100	cohort	Nunes et al. 2024 Expert Rev Vaccines quote RESULTS: XBB.1.5 VE against COVID-19 hospitalizations was 50% (95%CI: 45 to 55) and 41% (95%CI: 35 to 46) in 65-79-year-olds and in ≥80-year-olds, respectively. abstract, RESULTS Oldest age band: the same sentence gives higher VE in sixty-five to seventy-nine year olds. The comparator had earlier doses and infections, so this is the added protection of an updated dose, not protection versus never-vaccinated. VE declined over time in all age groups per the abstract.
COVID-19-associated hospitalisation severity: hospitalisation strain: XBB and JN.1 periods case definition: Hospitalisation with COVID-19-like illness and a positive SARS-CoV-2 test, VISION network	18 years or older, median 71 years among hospitalisations immune status: immunocompetent country: United States, 6 health care systems period: September 21, 2023 to August 22, 2024 18-49y50-64y65+	2023-2024 monovalent XBB.1.5 COVID-19 vaccine platform: mRNA or protein (products approved in the US) doses: 1 updated dose on top of prior doses time since vaccination: 180 to 299 days after vaccination vs no 2023-2024 dose	-4 (-14–5) VE (%)	test-negative	Link-Gelles et al. 2025 JAMA Netw Open quote VE was highest 7 to 59 days after vaccination (VE against ED and UC encounters 49%; 95% CI, 46%-52%; hospitalization, 51%; 95% CI, 46%-56%; critical illness, 68%; 95% CI, 56%-76%) and then waned (VE 180-299 days after vaccination against ED and UC encounters, -7% [95% CI, -13% to -2%]; hospitalization, -4% [95% CI, -14% to 5%]; and critical illness, 16% [95% CI, -6 to 34%]). abstract, RESULTS Null-to-negative waning record: by six to ten months the updated dose gave no measurable protection against hospitalisation. The same sentence shows the early (seven to fifty-nine day) estimates were substantial and that protection against critical illness lasted longer. The comparator group had prior vaccination and infection.
COVID-19-associated hospitalisation severity: hospitalisation strain: 2024-2025 season (JN.1-derived lineages) case definition: Hospitalisation with COVID-19-like illness and a positive SARS-CoV-2 test, VISION network	65 years and older immune status: immunocompetent country: United States, 6 states period: September 5, 2024 to September 2, 2025 n: 63,958 hospitalisations in adults 65 and older 65+	2024-2025 COVID-19 vaccine formulation platform: mRNA or protein (products approved in the US) doses: 1 updated dose on top of prior doses time since vaccination: 7 to 299 days after vaccination vs no 2024-2025 dose	35 (29–40) VE (%)	test-negative	Wiegand et al. 2026 JAMA Intern Med quote Among immunocompetent adults 65 years and older (122 663 ED/UC encounters and 63 958 hospitalizations), estimated VE was 26% (95% CI, 22%-30%) against COVID-19-associated ED/UC encounters, 35% (95% CI, 29%-40%) against COVID-19-associated hospitalization, and 41% (95% CI, 28%-52%) against COVID-19-associated critical illness 7 to 299 days after vaccination. abstract, RESULTS Season-average estimate across up to ten months, so it blends early higher and later lower protection; the abstract states VE waned with time. The comparator had prior immunity.
COVID-19-associated hospitalisation severity: hospitalisation strain: 2024-2025 season (JN.1-derived lineages) case definition: Hospitalisation with COVID-19-like illness and a positive SARS-CoV-2 test, VISION network	18 years and older immune status: immunocompromised country: United States, 6 states period: September 5, 2024 to September 2, 2025 n: 32,629 hospitalisations in immunocompromised adults 18-49y50-64y65+	2024-2025 COVID-19 vaccine formulation platform: mRNA or protein (products approved in the US) doses: 1 updated dose on top of prior doses time since vaccination: 7 to 299 days after vaccination vs no 2024-2025 dose	24 (13–34) VE (%)	test-negative	Wiegand et al. 2026 JAMA Intern Med quote Among 32 629 hospitalizations in immunocompromised adults 18 years and older, estimated VE against COVID-19-associated hospitalization was 24% (95% CI, 13%-34%). abstract, RESULTS Lower than the immunocompetent estimate from the same network and season, consistent with reduced vaccine response in immunocompromised people.
COVID-19 infection followed by hospitalisation or death severity: hospitalisation or death strain: Delta variant period case definition: Positive virology test followed by hospital admission or death, linked records	immunosuppressed people in the sentinel network, all vaccinated ages immune status: immunosuppressed country: England period: Delta-dominant period, 2021 18-49y50-64y65+	Comirnaty (BNT162b2) primary course plus third dose platform: mRNA doses: 3 time since vaccination: 14 to 69 days after the third dose vs unvaccinated	91.9 (85.9–95.4) adjusted VE (%)	cohort	Whitaker et al. 2023 J Infect quote Lower aVE was observed in the immunosuppressed group: 88.6% (79.1%-93.8%) and 91.9% (85.9%-95.4%) for Vaxzevria and Comirnaty respectively. abstract, FINDINGS The same sentence gives the Vaxzevria figure. Still high, but lower than the clinically vulnerable non-immunosuppressed group in the preceding sentence, and antibody levels were lower in the immunosuppressed group across all vaccines and doses.
COVID-19-associated hospitalisation within 30 days of a positive test severity: hospitalisation (conditional on infection) strain: Delta surge case definition: Hospitalisation within 30 days of a positive SARS-CoV-2 test among veterans testing positive	veterans aged 19 or older, mean 57.5 years sex: predominantly male risk group: frail (frailty index) country: United States (Veterans Health Administration) period: July 25 to September 30, 2021 n: 12,550 frail veterans among 57,784 testing positive 18-49y50-64y65+	mRNA COVID-19 vaccines platform: mRNA doses: as recorded (vaccinated vs unvaccinated) vs unvaccinated veterans testing positive	36 (30–42) VE (%) = 1 - OR for hospitalisation given infection	cohort	Tang et al. 2022 Lancet Healthy Longev quote Vaccine effectiveness against COVID-19-associated hospitalisation within 30 days of a positive SARS-CoV-2 test was 65% (95% CI 61-69) in the robust group, 54% (48-58) in the pre-frail group, and 36% (30-42) in the frail group. abstract, FINDINGS Conditional on having tested positive, so this measures protection against progression, not against infection; it is not comparable to population VE. The same sentence gives much higher VE in robust veterans, so frailty blunts protection.
Severe COVID-19 (infection leading to hospitalisation or death) severity: hospitalisation or death strain: Omicron case definition: Notified SARS-CoV-2 infection leading to hospitalisation or death, national surveillance linked to vaccination registry	5-11 years prior infection: no previous diagnosis of infection country: Italy period: January 17 to April 13, 2022 n: 2,965,918 children 5-11y	BNT162b2 (Pfizer-BioNTech), paediatric dose platform: mRNA doses: 2 vs unvaccinated children	41.1 (22.2–55.4) VE (%)	cohort	Sacco et al. 2022 Lancet quote Overall, vaccine effectiveness in the fully vaccinated group was 29·4% (95% CI 28·5-30·2) against SARS-CoV-2 infection and 41·1% (22·2-55·4) against severe COVID-19, whereas vaccine effectiveness in the partly vaccinated group was 27·4% (26·4-28·4) against SARS-CoV-2 infection and 38·1% (20·9-51·5) against severe COVID-19. abstract, FINDINGS Lower than the pooled hospitalisation VE in the meta-analysis record, and the authors note effectiveness in this age group was lower than in people aged twelve and over. Few severe events (hundreds of hospitalisations, a handful of ICU admissions and deaths) in nearly three million children.
COVID-19-associated emergency department visit or hospitalisation severity: ED visit or hospitalisation strain: Omicron era (BA.5 to XBB) case definition: Medically attended acute respiratory illness with a positive SARS-CoV-2 test, New Vaccine Surveillance Network	6 months to 4 years country: United States period: July 1, 2022 to September 30, 2023 n: 7,434 children Infant <1y1-4y	COVID-19 mRNA vaccines (BNT162b2 or mRNA-1273), paediatric doses platform: mRNA doses: 2 or more vs unvaccinated children	40 (8–60) VE (%)	test-negative	Tannis et al. 2023 MMWR Morb Mortal Wkly Rep quote When compared with receipt of no vaccines among children, receipt of ≥2 COVID-19 mRNA vaccine doses was 40% effective (95% CI = 8%-60%) in preventing ED visits and hospitalization. abstract Only about a tenth of enrolled children had two or more doses, hence the wide interval. Real-world estimate in the youngest group against a medically attended outcome.
COVID-19-related hospitalisation severity: hospitalisation strain: Omicron (BA.1 through XBB) case definition: Hospitalisation with a positive SARS-CoV-2 test, Overcoming COVID-19 Network case-control	5-18 years country: United States period: December 19, 2021 to October 29, 2023 5-11y12-17y	original monovalent mRNA COVID-19 vaccine platform: mRNA doses: 2 or more time since vaccination: 120 to 364 days since the most recent dose vs unvaccinated (test-negative controls)	19 (2–32) VE (%)	case-control	Zambrano et al. 2024 MMWR Morb Mortal Wkly Rep quote VE of the original monovalent vaccine against COVID-19-related hospitalizations was 52% (95% CI = 33%-66%) when the most recent dose was administered <120 days before hospitalization and 19% (95% CI = 2%-32%) if the interval was 120-364 days. abstract Waning in children and adolescents: the same sentence gives the higher VE when the last dose was under four months old. Most hospitalised case-patients were unvaccinated despite frequent underlying conditions.
Hospital admission with COVID-19 in infants under 6 months (maternal vaccination) severity: hospitalisation strain: Delta (94.7) and Omicron (78.7) in the same sentence case definition: Hospital admission with PCR-confirmed SARS-CoV-2 infection in infants aged up to six months	infants aged up to six months pregnancy: infants of mothers vaccinated during pregnancy (last dose in the third trimester) country: England period: infants born in 2021, Delta and Omicron periods Infant <1y	maternal COVID-19 vaccination, two doses, last dose in the third trimester platform: mRNA and adenovirus vector (UK programme) doses: 2 maternal doses time since vaccination: infant's first six months of life vs infants of unvaccinated mothers (test-negative)	94.7 (78.2–98.7) VE (%) of maternal vaccination for the infant	test-negative	Kirsebom et al. 2024 BMJ Med quote The effectiveness of two maternal doses when the last dose was given in the third trimester was 86.5% (95% CI 81.9% to 90.0%) and 56.6% (46.7% to 64.6%) against symptomatic disease with delta and omicron infection, respectively, in infants, and effectiveness against hospital admission was 94.7% (78.2% to 98.7%) and 78.7% (58.2% to 89.1%), respectively. abstract, RESULTS Delta-period estimate; the Omicron-period estimate against infant hospital admission in the same sentence is lower but still substantial. Protection was highest when maternal vaccination occurred later in pregnancy. This is the counterpart to the under-six-month hospitalisation burden record.
COVID-19-associated emergency department or urgent care encounter in pregnancy severity: medically attended (ED/UC) strain: Omicron case definition: Laboratory-confirmed COVID-19-associated ED/UC encounter among pregnant people with COVID-like illness	pregnant people, median 28 years pregnancy: pregnant (at least one dose received during pregnancy) country: United States, 10 states period: Omicron predominance, to June 2022 18-49y	COVID-19 mRNA vaccine platform: mRNA doses: 3 time since vaccination: 120 or more days after the third dose vs unvaccinated pregnant people	-124 (-414–2) VE (%)	test-negative	Schrag et al. 2022 JAMA Netw Open quote During Omicron predominance, for ED/UC encounters, the estimated VE of 2 doses within 14 to 149 days, 2 doses 150 or more days, 3 doses within 7 to 119 days, and 3 doses 120 or more days prior was 3% (95% CI, -49% to 37%), 42% (95% CI, -16% to 72%), 79% (95% CI, 59% to 89%), and -124% (95% CI, -414% to 2%), respectively; for hospitalization, estimated VE was 86% (95% CI, 41% to 97%), 64% (95% CI, -102% to 93%), 86% (95% CI, 28% to 97%), and -53% (95% CI, -1254% to 83%), respectively. abstract, RESULTS A negative point estimate with an interval reaching above zero: statistically compatible with no effect, and with very few events. It is included because the rules forbid selection; the same sentence gives substantial VE for a recent third dose, and hospitalisation VE in the same abstract was higher. Interpret as no demonstrable protection against mild Omicron illness four months after a booster, not as harm.

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
Serious adverse events after vaccination severity: serious adverse event case definition: Serious adverse events as reported by the included RCTs	adults country: multinational period: trials to November 2021 n: 34,072 participants in 2 RCTs 18-49y50-64y65+	mRNA-1273 (Moderna) platform: mRNA doses: 2 vs placebo	0.92 (0.78–1.08) risk ratio for serious adverse events vs placebo	systematic review GRADE: moderate 2 RCTs	Graña et al. 2022 Cochrane Database Syst Rev quote Serious adverse events (SAEs) mRNA-1273, ChAdOx1 (Oxford-AstraZeneca)/SII-ChAdOx1 (Serum Institute of India), Ad26.COV2.S, and BBV152 probably result in little or no difference in SAEs compared to placebo (RR: mRNA-1273: 0.92, 95% CI 0.78 to 1.08; 2 RCTs, 34,072 participants; ChAdOx1/SII-ChAdOx1: 0.88, 95% CI 0.72 to 1.07; 7 RCTs, 58,182 participants; Ad26.COV2.S: 0.92, 95% CI 0.69 to 1.22; 1 RCT, 43,783 participants); BBV152: 0.65, 95% CI 0.43 to 0.97; 1 RCT, 25,928 participants). abstract, MAIN RESULTS, serious adverse events Cochrane rated this probably little or no difference, with an absolute difference likely under five per thousand. The same sentence gives similar ratios for the adenovirus and BBV152 products; for the Pfizer-BioNTech mRNA vaccine the review judged the SAE evidence uncertain.
Myocarditis or pericarditis within 4 weeks after first vaccination severity: myocarditis or pericarditis case definition: First myocarditis or pericarditis record in linked primary and secondary care data	5 to under 18 years country: England setting: whole-population linked electronic health records period: August 6, 2021 to December 31, 2022 n: 9,245,395 vaccine-eligible individuals, of whom 3,407,560 received a first dose 5-11y12-17y	BNT162b2 (Pfizer-BioNTech) platform: mRNA doses: 1 (first dose) time since vaccination: first 4 weeks after vaccination vs unvaccinated or time before vaccination, adjusted	1.84 (1.25–2.72) adjusted hazard ratio vs no or before vaccination	cohort	Sampri et al. 2025 Lancet Child Adolesc Health quote COVID-19 vaccination (compared with no or before vaccination) was associated with elevated risk of myocarditis or pericarditis within the first 4 weeks after vaccination (1·84 [1·25-2·72]). abstract, FINDINGS The same study's post-infection myocarditis hazard is a post-acute record. The abstract gives six-month absolute excess risks per hundred thousand for both exposures, with the post-infection excess larger than the post-vaccination excess; the two numbers should be shown together.

Post-acute sequelae of SARS-CoV-2 infection (long COVID, MIS-C, post-infection cardiovascular events) SARS-CoV-2

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
Post-COVID-19 condition (any persistent symptom at 28 or more days) severity: any persistent symptom case definition: Post-COVID-19 condition at 28+ days from infection as defined by the included studies	all ages as included in the primary studies prior infection: confirmed SARS-CoV-2 infection vaccination status: not reported country: multiple (global) period: studies to March 2022 n: 41 studies meta-analysed All ages	vs none (single-arm prevalence, no uninfected comparator)	0.43 (.39–.46) pooled prevalence (proportion) per infected person follow-up: 28 or more days after infection	meta-analysis	Chen et al. 2022 J Infect Dis quote Global estimated pooled prevalence of post-COVID-19 condition was 0.43 (95% confidence interval [CI], .39-.46). abstract, RESULTS Uncontrolled prevalence: no uninfected comparison group, so background symptom rates are not subtracted. Heavily weighted towards early-pandemic, unvaccinated, often hospitalised cohorts; controlled estimates in this file are lower.
Long COVID in children and adolescents (NICE definition) severity: any persistent symptom case definition: Ongoing (4 to 12 weeks) and post-COVID-19 (12 weeks or more) symptoms per NICE definition	0 to 18 years prior infection: SARS-CoV-2 infection vaccination status: not reported country: multiple period: studies published before February 2022 n: 80,071 children and adolescents in 21 studies Infant <1y1-4y5-11y12-17y	vs none for the pooled prevalence; some included studies had uninfected controls	25.24 pooled prevalence (%) per infected child	meta-analysis	Lopez-Leon et al. 2022 Sci Rep quote The prevalence of long-COVID was 25.24%, and the most prevalent clinical manifestations were mood symptoms (16.50%), fatigue (9.66%), and sleep disorders (8.42%). abstract The authors list lack of standardised definitions, recall and selection bias, loss to follow-up and high heterogeneity as limitations. Controlled comparisons within the review showed excess dyspnoea, anosmia and fever only, so most of this prevalence is not attributable.
New-onset diabetes after COVID-19 severity: incident diabetes case definition: Newly diagnosed diabetes in COVID-19 survivors in the included cohort studies	median 43 years (IQR 35-49) prior infection: COVID-19 vaccination status: not reported country: multiple period: studies to October 2022 n: 4,270,747 COVID-19 patients and 43,203,759 controls in 8 studies 18-49y50-64y	vs non-COVID-19 controls as defined in the included studies	1.66 (1.38–2.00) risk ratio vs non-COVID controls	meta-analysis	Ssentongo et al. 2022 Sci Rep quote COVID-19 was associated with a 66% higher risk of incident diabetes (risk ratio, 1.66; 95% CI 1.38; 2.00). abstract Observational cohorts: detection bias (more glucose testing after COVID) and unmeasured confounding are the main threats; the review reports the risk was not modified by age, sex or study quality.
Post-acute sequelae of SARS-CoV-2 infection (PASC), cumulative incidence at 1 year, unvaccinated, pre-Delta era severity: any PASC diagnosis strain: pre-Delta (ancestral and Alpha) case definition: Pre-specified PASC outcomes in VA health records, relative to noninfected contemporaneous controls	adults (US veterans) sex: predominantly male veteran population prior infection: SARS-CoV-2 infection vaccination status: unvaccinated country: United States setting: Veterans Affairs health system period: March 2020 to January 2022 n: 441,583 infected and 4,748,504 noninfected controls 18-49y50-64y65+	vs noninfected contemporaneous controls	10.42 (10.22–10.64) cumulative incidence of PASC at 1 year, events per 100 persons per 100 infected persons follow-up: 1 year	cohort	Xie et al. 2024 N Engl J Med quote RESULTS: Among unvaccinated persons infected with SARS-CoV-2, the cumulative incidence of PASC during the first year after infection was 10.42 events per 100 persons (95% confidence interval [CI], 10.22 to 10.64) in the pre-delta era, 9.51 events per 100 persons (95% CI, 9.26 to 9.75) in the delta era, and 7.76 events per 100 persons (95% CI, 7.57 to 7.98) in the omicron era (difference between the omicron and pre-delta eras, -2.66 events per 100 persons [95% CI, -2.93 to -2.36]; difference between the omicron and delta eras, -1.75 events per 100 persons [95% CI, -2.08 to -1.42]). abstract, RESULTS Excess over uninfected controls, so background rates are subtracted. Veteran population is older and mostly male, limiting transfer to children and women. Era records for Omicron unvaccinated and Omicron vaccinated follow.
Post-acute sequelae of SARS-CoV-2 infection (PASC), cumulative incidence at 1 year, unvaccinated, Omicron era severity: any PASC diagnosis strain: Omicron case definition: Pre-specified PASC outcomes in VA health records, relative to noninfected contemporaneous controls	adults (US veterans) sex: predominantly male veteran population prior infection: SARS-CoV-2 infection vaccination status: unvaccinated country: United States setting: Veterans Affairs health system period: Omicron era, to January 2022 18-49y50-64y65+	vs noninfected contemporaneous controls	7.76 (7.57–7.98) cumulative incidence of PASC at 1 year, events per 100 persons per 100 infected persons follow-up: 1 year	cohort	Xie et al. 2024 N Engl J Med quote RESULTS: Among unvaccinated persons infected with SARS-CoV-2, the cumulative incidence of PASC during the first year after infection was 10.42 events per 100 persons (95% confidence interval [CI], 10.22 to 10.64) in the pre-delta era, 9.51 events per 100 persons (95% CI, 9.26 to 9.75) in the delta era, and 7.76 events per 100 persons (95% CI, 7.57 to 7.98) in the omicron era (difference between the omicron and pre-delta eras, -2.66 events per 100 persons [95% CI, -2.93 to -2.36]; difference between the omicron and delta eras, -1.75 events per 100 persons [95% CI, -2.08 to -1.42]). abstract, RESULTS Lower than the pre-Delta figure from the same cohort but still substantial in unvaccinated people. Decomposition in the same abstract attributes most of the era decline to vaccination rather than to the virus.
Post-acute sequelae of SARS-CoV-2 infection (PASC), cumulative incidence at 1 year, vaccinated, Omicron era severity: any PASC diagnosis strain: Omicron case definition: Pre-specified PASC outcomes in VA health records, relative to noninfected contemporaneous controls	adults (US veterans) sex: predominantly male veteran population prior infection: SARS-CoV-2 infection vaccination status: vaccinated country: United States setting: Veterans Affairs health system period: Omicron era, to January 2022 18-49y50-64y65+	vs noninfected contemporaneous controls	3.50 (3.31–3.71) cumulative incidence of PASC at 1 year, events per 100 persons per 100 infected persons follow-up: 1 year	cohort	Xie et al. 2024 N Engl J Med quote Among vaccinated persons, the cumulative incidence of PASC at 1 year was 5.34 events per 100 persons (95% CI, 5.10 to 5.58) during the delta era and 3.50 events per 100 persons (95% CI, 3.31 to 3.71) during the omicron era (difference between the omicron and delta eras, -1.83 events per 100 persons; 95% CI, -2.14 to -1.52). abstract, RESULTS Vaccinated people infected in the Omicron era: the lowest PASC incidence in the series, but the authors stress it remains substantial. Compare with the unvaccinated Omicron record from the same cohort.
Acute myocardial infarction in the first week after COVID-19 severity: acute myocardial infarction strain: ancestral (2020) case definition: ICD-coded first acute myocardial infarction as cause of hospital admission, national registers	all COVID-19 cases in Sweden (all ages) prior infection: COVID-19 vaccination status: unvaccinated country: Sweden setting: national registers period: February 1 to September 14, 2020 n: 86,742 patients with COVID-19 All ages	vs the same individuals' control periods (self-controlled case series)	2.89 (1.51–5.55) incidence rate ratio vs control periods (first week, day of exposure excluded) follow-up: first week after COVID-19	SCCS	Katsoularis et al. 2021 Lancet quote When day of exposure was excluded from the risk period in the SCCS, the IRR for acute myocardial infarction was 2·89 (95% CI 1·51-5·55) for the first week, 2·53 (1·29-4·94) for the second week, and 1·60 (0·84-3·04) in weeks 3 and 4 following COVID-19. abstract, FINDINGS Self-controlled design removes fixed confounders. Excluding the day of exposure is the conservative analysis; including it gives a much larger ratio in the same abstract because infarctions diagnosed on the same day as COVID-19 are counted. Risk falls over subsequent weeks.
Ischaemic stroke in the first week after COVID-19 severity: ischaemic stroke strain: ancestral (2020) case definition: ICD-coded first ischaemic stroke as cause of hospital admission, national registers	all COVID-19 cases in Sweden (all ages) prior infection: COVID-19 vaccination status: unvaccinated country: Sweden setting: national registers period: February 1 to September 14, 2020 n: 86,742 patients with COVID-19 All ages	vs the same individuals' control periods (self-controlled case series)	2.97 (1.71–5.15) incidence rate ratio vs control periods (first week, day of exposure excluded) follow-up: first week after COVID-19	SCCS	Katsoularis et al. 2021 Lancet quote The corresponding IRRs for ischaemic stroke when day of exposure was excluded from the risk period were 2·97 (1·71-5·15) in the first week, 2·80 (1·60-4·88) in the second week, and 2·10 (1·33-3·32) in weeks 3 and 4 following COVID-19; when day of exposure was included in the risk period, the IRRs were 6·18 (4·06-9·42) for the first week, 2·85 (1·64-4·97) for the second week, and 2·14 (1·36-3·38) for weeks 3 and 4 following COVID-19. abstract, FINDINGS Self-controlled design; same caveats as the myocardial infarction record. The stroke excess persists into weeks three and four in the same sentence, longer than the infarction excess.
Multisystem inflammatory syndrome in children (MIS-C) after Delta infection, unvaccinated severity: MIS-C (hospitalised hyperinflammatory syndrome) strain: Delta case definition: CDC MIS-C case definition, nationwide prospective ascertainment from all paediatric departments	0-17 years prior infection: SARS-CoV-2 Delta infection vaccination status: unvaccinated country: Denmark setting: nationwide prospective cohort period: August 1, 2021 to February 1, 2022 n: 51 MIS-C cases among unvaccinated individuals Infant <1y1-4y5-11y12-17y	vs vaccinated individuals with breakthrough infection (same sentence)	one in 3400 (2600–4600) risk of MIS-C per infected unvaccinated child (one in N) per infected unvaccinated child follow-up: after infection	cohort	Nygaard et al. 2022 Lancet Child Adolesc Health quote The incidence of MIS-C was one in 3400 unvaccinated individuals (95% CI 2600-4600) with the delta variant and one in 9900 vaccinated individuals (95% CI 1800-390 000) with breakthrough infection. abstract, FINDINGS The interval is the CI on the denominator N, not on a proportion. Infections are estimated from surveillance registries, so under-ascertained infections would make the true risk lower. Vaccine effectiveness against MIS-C from the same cohort is an efficacy record.
Myocarditis or pericarditis in the first week after COVID-19 diagnosis severity: myocarditis or pericarditis case definition: First myocarditis or pericarditis record in linked primary and secondary care data	under 18 years prior infection: first COVID-19 diagnosis (positive test or diagnosis code) vaccination status: mixed country: England setting: whole-population linked electronic health records period: January 1, 2020 to March 31, 2022 n: 13,896,125 individuals under 18, of whom 3,903,410 had a COVID-19 diagnosis Infant <1y1-4y5-11y12-17y	vs no COVID-19 diagnosis or time before diagnosis, adjusted for age, sex, ethnicity, region, deprivation, GP contact frequency and medication	3.46 (2.06–5.80) adjusted hazard ratio vs no or before diagnosis follow-up: first week after diagnosis	cohort	Sampri et al. 2025 Lancet Child Adolesc Health quote COVID-19 diagnosis (compared with no or before diagnosis) was associated with higher risk of arterial thromboembolism (aHR 2·33 [95% CI 1·20-4·51]), venous thromboembolism (4·90 [3·66-6·55]), thrombocytopenia (3·64 [2·21-6·00]), myocarditis or pericarditis (3·46 [2·06-5·80]), and inflammatory conditions (14·84 [11·01-19·99]) in the first week after diagnosis. abstract, FINDINGS Residual confounding by health-seeking behaviour (children tested for COVID are also more likely to have cardiac symptoms investigated) is the main risk. Risk remained elevated beyond twelve months in the same abstract. The same study's post-vaccination myocarditis estimate is a safety record and its absolute six-month excess risks are given there.
Multisystem inflammatory syndrome in children (MIS-C) per SARS-CoV-2 infection severity: MIS-C (hospitalised hyperinflammatory syndrome) strain: ancestral (2020) case definition: CDC MIS-C case definition, enhanced surveillance; infections estimated with published under-detection multipliers	under 21 years, median 8 years prior infection: SARS-CoV-2 infection vaccination status: unvaccinated country: United States, 7 jurisdictions setting: surveillance period: April to June 2020 n: 248 persons with MIS-C Infant <1y1-4y5-11y12-17y18-49y	vs none (incidence among infected persons)	316 (278–357) incidence per 1,000,000 SARS-CoV-2 infections per 1,000,000 estimated infections	surveillance	Payne et al. 2021 JAMA Netw Open quote MIS-C incidence per 1 000 000 SARS-CoV-2 infections was 316 (95% CI, 278-357) persons and was higher among Black (aIRR, 5.62 [95% CI, 3.68-8.60]), Hispanic or Latino (aIRR, 4.26 [95% CI, 2.85-6.38]), and Asian or Pacific Islander persons (aIRR, 2.88 [95% CI, 1.42-5.83]) compared with White persons. abstract, RESULTS The denominator is modelled from reported cases with under-detection multipliers, so the absolute rate depends on those multipliers. Pre-vaccine, ancestral-strain era; incidence fell in later variant eras.

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
Multisystem inflammatory syndrome in children (MIS-C) severity: MIS-C strain: Omicron case definition: MIS-C as defined by the included study	5-11 years country: as enrolled in the single included study period: studies to January 23, 2023 5-11y	mRNA COVID-19 vaccine (paediatric) platform: mRNA doses: 2 vs unvaccinated children	78 (48–90) VE (%)	meta-analysis GRADE: very low 1 non-randomised study	Piechotta et al. 2023 Lancet Child Adolesc Health quote Vaccine effectiveness after two doses against omicron infections was 41·6% (95% CI 28·1-52·6; eight non-randomised studies of interventions [NRSIs]; CoE low), 36·2% (21·5-48·2; six NRSIs; CoE low) against symptomatic COVID-19, 75·3% (68·0-81·0; six NRSIs; CoE moderate) against COVID-19-related hospitalisations, and 78% (48-90, one NRSI; CoE very low) against MIS-C. abstract, FINDINGS Single study, very low certainty. The Danish Delta-era cohort in this file gives a separate, higher estimate for ages five to seventeen.
Long COVID after SARS-CoV-2 infection severity: any long COVID case definition: Long COVID as defined by the included observational studies	adults, mean age 41 to 67 across studies prior infection: SARS-CoV-2 infection after vaccination (breakthrough) vs after no vaccination country: multiple period: studies to September 2022 n: 536,291 unvaccinated and 84,603 vaccinated patients in 6 studies 18-49y50-64y65+	COVID-19 vaccines (as used in the included studies) platform: mixed doses: 2 time since vaccination: vaccinated before infection vs unvaccinated infected people	0.64 (0.45–0.92) OR for long COVID, 2 doses vs no vaccination	meta-analysis	Watanabe et al. 2023 Vaccine quote Two-dose vaccination was associated with a lower risk of long COVID compared to no vaccination (OR, 0.64; 95% confidence interval [CI], 0.45-0.92) and one-dose vaccination (OR, 0.60; 95% CI, 0.43-0.83). abstract, RESULTS Observational comparison among infected people; vaccinated and unvaccinated groups differ in age, health and testing. The same sentence gives the two-dose versus one-dose comparison. Among people who already had long COVID, most reported no symptomatic change after vaccination.
Multisystem inflammatory syndrome in children (MIS-C) after Delta infection severity: MIS-C strain: Delta case definition: CDC MIS-C case definition, nationwide prospective ascertainment	5-17 years country: Denmark period: August 1, 2021 to February 1, 2022 5-11y12-17y	COVID-19 vaccine (Danish programme, mRNA) platform: mRNA doses: fully vaccinated vs unvaccinated individuals, per infected person-years	94 (55–99) VE (%) = 1 - incidence rate ratio	cohort	Nygaard et al. 2022 Lancet Child Adolesc Health quote The estimated vaccine effectiveness against MIS-C after the delta variant was 94% (95% CI 55-99; p=0·0061) in individuals aged 5-17 years. abstract, FINDINGS Based on a single MIS-C case among vaccinated adolescents, so the interval is wide. The authors attribute the effect to prevention of infection and possibly a lower MIS-C risk after breakthrough infection. The unvaccinated MIS-C risk from the same cohort is a post-acute record.
Post-acute sequelae of SARS-CoV-2 infection (PASC) at 1 year, vaccinated vs unvaccinated infected persons severity: any PASC diagnosis strain: Omicron case definition: Pre-specified PASC outcomes in VA health records	adults (US veterans) sex: predominantly male veteran population prior infection: SARS-CoV-2 infection country: United States setting: Veterans Affairs health system period: Omicron era, to January 2022 18-49y50-64y65+	COVID-19 vaccines (as recorded in VA records) platform: mixed doses: as recorded time since vaccination: vaccinated before infection vs unvaccinated infected veterans, same era	-4.26 (-4.49–-4.05) difference in 1-year cumulative incidence of PASC, events per 100 infected persons (vaccinated minus unvaccinated)	cohort	Xie et al. 2024 N Engl J Med quote Vaccinated persons had a lower cumulative incidence of PASC at 1 year than unvaccinated persons (difference during the delta era, -4.18 events per 100 persons [95% CI, -4.47 to -3.88]; difference during the omicron era, -4.26 events per 100 persons [95% CI, -4.49 to -4.05]). abstract, RESULTS An absolute difference in events per hundred infected people, not a ratio. Vaccinated and unvaccinated veterans differ in ways the adjustment may not capture. Decomposition in the same abstract attributes most of the era-over-era decline in PASC to vaccination.

Gaps

No pre-vaccine-era population hospitalisation rate by age (e.g. COVID-NET 2020 cumulative rates) is compiled; the burden records for hospitalisation are Delta/Omicron-era surveillance peaks and vaccination-status comparisons. A 2020 COVID-NET age-stratified rate would complete the pre-vaccine picture.
The post-acute cardiovascular cohort (Xie 2022, Nature Medicine, PMID 35132265) reports hazard ratios for MI, stroke, heart failure and dysrhythmia only in the full text; its abstract carries no numbers, so no record was compiled from it. The Swedish SCCS covers acute MI and stroke in the first weeks only; a 1-year post-infection cardiovascular HR with uninfected comparator still needs a full-text snapshot.
No controlled estimate of long COVID in children versus uninfected controls was found in abstract form; the paediatric prevalence record is uncontrolled.
No record quantifies vaccine effectiveness against Delta-era hospitalisation in older adults separately from the mixed-age Qatar and Danish estimates; the Danish abstract states hospitalisation VE was above ninety-eight percent for Alpha and Delta but gives no point estimate with CI that could be compiled.
Searches for mRNA-1273 effectiveness in children 6 months to 4 years in a test-negative design, and for VE in children 6 months to 4 years against hospitalisation specifically (rather than ED visits plus hospitalisation combined), found no abstract with usable numbers beyond the KidCOVE RCT and the NVSN estimate compiled.
No HIV-specific or transplant-specific clinical VE record was compiled; the immunocompromised records are the pooled VISION immunocompromised estimate, the England immunosuppressed cohort and the cancer cohort. The BMJ meta-analysis on immunocompromised patients reports seroconversion, not clinical endpoints, and was not compiled.
No safety record was compiled for thrombosis with thrombocytopenia after adenovirus-vector vaccines or for myocarditis after mRNA vaccination in young adult males from an SCCS, because no such controlled source was fetched in the course of this efficacy-focused compilation. VDN covers vaccine harms; the two safety records here are only those that fell out of sources already in hand.
No LMIC-specific vaccine effectiveness record (e.g. CoronaVac or ChAdOx1 effectiveness in Brazil, Chile or sub-Saharan Africa) was compiled; the LMIC content is limited to the developing-country IFR record and the inactivated-vaccine RCT estimate from the Cochrane review.

Flags for review

covid-bur-001 to covid-bur-003 are infection fatality rates (denominator: all infections from serology) while covid-bur-005, covid-bur-007, covid-bur-008 and covid-bur-015 are case fatality rates with hospital, ICU, reported-case or positive-test denominators. They differ by orders of magnitude for reasons of denominator, not severity, and must not be shown in one column without the denominator label.
covid-bur-009, covid-bur-011 and covid-bur-013 are unadjusted or age-standardised surveillance comparisons by vaccination status. They are filed as burden with vacc=unvaccinated because the brief asks for burden by vaccination status, but they function as crude effectiveness ratios and are vulnerable to healthy-vaccinee bias and differential testing. Do not present them as vaccine effectiveness.
covid-pa-001 and covid-pa-003 are uncontrolled prevalence figures (no uninfected comparator) and are several times higher than the controlled excess-incidence figures in covid-pa-004 to covid-pa-006 from the VA cohort. A page that shows the uncontrolled prevalence alone will overstate attributable long COVID; show the controlled figures beside them.
covid-pa-011 records a risk as "one in 3400" with the CI given on the denominator (2600 to 4600), not on a proportion. The renderer and site must not treat 2600 and 4600 as bounds of a percentage.
covid-eff-006 (Ad26.COV2.S interim efficacy) resolves to a sentence fragment because the cache's sentence splitter breaks on the abbreviation vs. inside the parenthesis. The numbers (66.9, 59.0, 73.4) are correct and in the fragment; a reviewer should confirm the quote reads acceptably on the page.
covid-eff-008 (ChAdOx1) quotes the two-standard-dose efficacy; the same sentence contains the higher low-dose/standard-dose estimate from an unplanned subgroup, and the overall estimate in the following sentence uses a 95.8 percent CI, not 95 percent. Neither was compiled; if someone adds the overall estimate the CI level must be labelled.
covid-eff-022 and covid-eff-038 carry negative point estimates (VE -4 and -124). Both intervals include zero and both are late-waning strata of otherwise protective vaccines. They are compiled because the rules forbid selection; the page must display them with their intervals and the early-interval estimates from the same sentence, or readers will read them as evidence of harm.
covid-eff-020 (bivalent booster, VE 84 percent) has no confidence interval in the abstract and a median interval of under a month since the dose. It should not be compared with the season-average XBB.1.5 and 2024-2025 estimates (covid-eff-021 to 024) without noting the time-since-dose difference.
The 2023-2024 and 2024-2025 estimates (covid-eff-021 to 024) compare an updated dose against people who mostly had prior doses and prior infection. They are incremental effectiveness of an additional dose, not effectiveness versus never-vaccinated, and are not comparable with the RCT efficacies in covid-eff-001 to 011.
covid-eff-027 (frailty) is VE conditional on a positive test (protection against progression among infected veterans) and is not a population VE. It must not be averaged with the other hospitalisation VE records.
covid-eff-040 (hybrid immunity) combines vaccine and prior infection; the abstract does not state the reference group, so comparator is recorded as defined by the included studies. The previous-infection-only effectiveness figures in the same abstract could not be filed as vaccine records (no product) and are carried only in notes; a reader comparing infection-acquired with vaccine-acquired protection needs to open the source.
covid-pa-012 and covid-saf-002 come from the same English cohort and the same abstract, which also gives absolute six-month excess risks of myocarditis or pericarditis per hundred thousand after infection versus after vaccination. Those absolute figures were not compiled as records (they would need a comparator-free measure type) but are the numbers a parent would most want; consider adding them when the schema allows an absolute-excess measure.
Every efficacy estimate from a test-negative or cohort design against an unvaccinated comparator after 2022 is subject to depletion-of-susceptibles and prior-infection misclassification; the Omicron-era estimates against infection (covid-eff-013, 018, 035) are the ones most affected.

Search log (31 searches)

COVID-19 infection fatality rate by age systematic review meta-analysis · PubMed → Found PMID 33289900 (Levin 2020 age-specific IFR), 34604571 (Alimohamadi CFR meta-analysis), 38309460 (Xia CFR by variant), 35618305 (Levin developing countries); compiled as covid-bur-001 to covid-bur-005, 007 and 008.
long COVID post-acute sequelae incidence systematic review meta-analysis · PubMed → Found PMID 35429399 (Chen global prevalence), 35739136 (Lopez-Leon children), 36418912 (Ssentongo diabetes), 36774332 (Watanabe vaccination vs long COVID); compiled as covid-pa-001, 003, 007 and covid-eff-042.
safety and efficacy of the BNT162b2 mRNA Covid-19 vaccine Polack · PubMed → Found PMID 33301246 (Polack 2020) and 34525277 (Thomas 2021, 6 months); compiled as covid-eff-001 and 002.
Covid-19 vaccine effectiveness against omicron and delta variants Andrews test-negative England · PubMed → Found PMID 35249272 (Andrews 2022 NEJM) and 39902238 (Kirsebom 2024 pregnancy and infants); compiled as covid-eff-012, 013 and 037.
long-term cardiovascular outcomes of COVID-19 Xie Al-Aly · PubMed → Found PMID 35132265 (Xie 2022 Nat Med); abstract carries no numbers, so not compiled (see gaps).
efficacy and safety of the mRNA-1273 SARS-CoV-2 vaccine Baden · PubMed → Found PMID 33378609 (Baden 2021) and 34551225 (El Sahly 2021); compiled as covid-eff-004 and 005.
Ad26.COV2.S vaccine efficacy against Covid-19 Sadoff · PubMed → Found PMID 33882225 (Sadoff 2021) and 35139271 (Sadoff 2022 final); compiled as covid-eff-006 (final analysis fetched, not compiled).
ChAdOx1 nCoV-19 vaccine efficacy interim analysis randomised controlled trials Voysey · PubMed → Found PMID 33306989 (Voysey 2021); compiled as covid-eff-008.
NVX-CoV2373 efficacy phase 3 trial · PubMed → Found PMID 36210481 (Heath 2023, end of placebo-controlled phase); compiled as covid-eff-009.
protective effectiveness of prior SARS-CoV-2 infection and hybrid immunity systematic review meta-analysis · PubMed → Returned only antibody-waning reviews; re-run with author name below.
Bobrovitz protective effectiveness of previous SARS-CoV-2 infection and hybrid immunity against omicron · PubMed → Found PMID 36681084 (Bobrovitz 2023 Lancet ID); compiled as covid-eff-040.
BNT162b2 vaccine effectiveness children 5-11 years omicron · PubMed → Found PMID 37084750 (Piechotta 2023 meta-analysis), 35780801 (Sacco 2022 Italy), 36863005 (Glatman-Freedman Israel, fetched but not compiled as Sacco already carries the waning record); compiled as covid-eff-028 to 031.
COVID-19 vaccine effectiveness children 6 months 4 years · PubMed → Found PMID 36260859 (Anderson 2022 KidCOVE RCT), 38032834 (Tannis 2023 NVSN), 41379943 (Irving 2025 VISION children); compiled as covid-eff-033, 034 and covid-bur-014.
maternal COVID-19 vaccination during pregnancy infant hospitalization effectiveness · PubMed → Returned mostly reviews and antibody studies; the infant protection record comes from Kirsebom 2024 found in the Andrews search.
COVID-19 vaccine effectiveness immunocompromised systematic review meta-analysis · PubMed → Found PMID 35236664 (Lee 2022 BMJ, seroconversion only, fetched but not compiled); clinical immunocompromised records came from later searches.
multisystem inflammatory syndrome in children incidence per SARS-CoV-2 infections · PubMed → Found PMID 34110391 (Payne 2021) and 35526537 (Nygaard 2022 Denmark); compiled as covid-pa-010, 011 and covid-eff-043.
myocarditis risk after SARS-CoV-2 infection versus vaccination cohort · PubMed → Found PMID 41198364 (Sampri 2025 England children) and 42607625 (Toraih 2026 TriNetX); compiled as covid-pa-012 and covid-saf-002 (Toraih fetched, not compiled).
Cochrane efficacy and safety of COVID-19 vaccines · PubMed → Found PMID 36473651 (Grana 2022 Cochrane); compiled as covid-eff-010, 011 and covid-saf-001.
COVID-19 vaccine effectiveness hospitalization adults 65 years older omicron VISION · PubMed → Found PMID 40560584 (Link-Gelles 2025 JAMA Netw Open 2023-2024 VE), 38421945 (DeCuir 2024 MMWR, fetched, superseded by the full-season paper), 39535047 (Nunes 2024 VEBIS older adults); compiled as covid-eff-021 and 022.
COVID-19 mRNA vaccine effectiveness hospitalization unvaccinated versus vaccinated rates MMWR 2021 delta · PubMed → Found PMID 34710076 (Taylor 2021 COVID-NET Delta severity; fetched, not compiled as its figures are proportions of hospitalised patients rather than rates).
2023-2024 XBB.1.5 COVID-19 vaccine effectiveness hospitalization adults · PubMed → Found PMID 38547037 (Link-Gelles 2024 immunocompromised XBB.1.5, fetched; superseded by the 2024-2025 VISION immunocompromised estimate compiled as covid-eff-024).
SARS-CoV-2 infection risk of myocardial infarction stroke self-controlled case series · PubMed → Found PMID 34332652 (Katsoularis 2021 Sweden SCCS); compiled as covid-pa-008 and 009.
COVID-19 hospitalization rates by age unvaccinated vaccinated COVID-NET · PubMed → Returned no usable results with this wording; re-run below.
long COVID vaccinated unvaccinated post-acute sequelae cohort veterans · PubMed → Found PMID 39018527 (Xie 2024 NEJM PASC by era); compiled as covid-pa-004 to 006 and covid-eff-044.
COVID-19 hospitalization rates unvaccinated vaccinated adults MMWR · PubMed → Found PMID 35085223 (Johnson 2022 case and death IRRs), 35176003 (Marks 2022 children COVID-NET), 35324880 (Taylor 2022 adults Delta/Omicron COVID-NET), 36006841 (Havers 2022 BA.2, fetched, not compiled); compiled as covid-bur-009 to 011.
COVID-19 pediatric hospitalization rate omicron children MMWR · PubMed → Found PMID 35446827 (Shi 2022 children 5-11 COVID-NET); compiled as covid-bur-013.
bivalent COVID-19 vaccine effectiveness hospitalization adults · PubMed → Found PMID 36580424 (Surie 2022 IVY bivalent 65+); compiled as covid-eff-020.
COVID-19 vaccination pregnancy effectiveness pregnant women meta-analysis · PubMed → Found PMID 35538060 (Prasad 2022 Nat Commun); compiled as covid-eff-039.
COVID-19 vaccine effectiveness immunocompromised hospitalization omicron · PubMed → Found PMID 38635481 (Zambrano 2024 durability in children 5-18); compiled as covid-eff-035.
COVID-19 vaccine effectiveness older adults 65 years hospitalization test-negative · PubMed → Found PMID 42295789 (Wiegand 2026 2024-2025 VE) and 35617989 (Lee 2022 cancer UKCCEP); compiled as covid-eff-023 and 024 (cancer cohort fetched, not compiled).
COVID-19 mRNA vaccine effectiveness delta variant hospitalization · PubMed → Found PMID 34728831 (Tang 2021 Qatar Delta), 36048766 (Gram 2022 Denmark), 36156146 (Schrag 2022 pregnancy), 37579793 (Whitaker 2023 clinical risk groups), 35935474 (Tang 2022 frailty); compiled as covid-eff-015 to 019, 026, 027, 038 and covid-bur-015.