1. Basic Information
Respiratory syncytial virus (RSV) is a leading cause of bronchiolitis and pneumonia in infants and a significant cause of morbidity in older adults. U.S. prevention now includes three distinct product classes — not interchangeable:
| Product | Type | Who | Manufacturer |
|---|---|---|---|
| Arexvy | Adjuvanted recombinant RSV vaccine (GSK) | Adults ≥60; pregnancy indication (maternal immunization) | GSK |
| Abrysvo | Bivalent recombinant RSV prefusion F vaccine (Pfizer) | Adults ≥60; maternal immunization (32–36 wks) | Pfizer |
| Beyfortus (nirsevimab) | Long-acting RSV monoclonal antibody — not a vaccine | Infants & toddlers (seasonal) | AstraZeneca / Sanofi |
Source: FDA prescribing information; CDC RSV pages (2024–2026). Beyfortus reports in VAERS may appear under RSV product labels.
Ingredients (Package Insert)
Structured composition for 2 branded products covered on this page, taken from FDA-approved package inserts (DailyMed / manufacturer prescribing information). Lists are per product — formulations differ by manufacturer and presentation. Click an ingredient name to open its safety-context page when available.
Arexvy GlaxoSmithKline Biologicals · Recombinant protein
Delivery
Route: Intramuscular (IM)
Form: Lyophilized powder (reconstitute)
Dose volume: 0.5 mL
Presentation: antigen vial + AS01E adjuvant suspension
Encapsulation / delivery vehicle
Liposome — AS01E is a liposomal adjuvant system (half-dose AS01 relative to AS01B).
| Component | Role | Amount |
|---|---|---|
| DOPC | liposomal phospholipid | 0.5 mg |
| Cholesterol | cholesterol | 0.125 mg |
Antigens
| Antigen | Type | Amount / dose |
|---|---|---|
| Recombinant RSV prefusion F glycoprotein (RSVPreF3) | Recombinant protein | 120 mcg |
Adjuvants
- AS01E — MPL 25 mcg + QS-21 25 mcg
- MPL — 25 mcg
- QS-21 — 25 mcg
Preservatives
- None — Single-dose presentation; label states no preservative.
Excipients & residuals
| Ingredient | Category | Amount | Role |
|---|---|---|---|
| Trehalose | Stabilizer | 14.7 mg | stabilizer |
| Sodium chloride | Buffer | 4.4 mg | tonicity |
| Potassium dihydrogen phosphate | Buffer | 0.83 mg | buffer |
| Dipotassium phosphate | Buffer | 0.26 mg | buffer |
| Polysorbate 80 | Surfactant | 0.18 mg | surfactant |
| Disodium phosphate anhydrous | Buffer | 0.15 mg | buffer |
Source: FDA package insert · Verified 2026-07-09
Abrysvo Pfizer Inc. · Recombinant protein
Delivery
Route: Intramuscular (IM)
Form: Lyophilized powder (reconstitute)
Dose volume: 0.5 mL
Presentation: single-dose vial + sterile water diluent / prefilled presentations per labeling
Encapsulation / delivery vehicle
None (no nanoparticle/VLP encapsulation system)
Antigens
| Antigen | Type | Amount / dose |
|---|---|---|
| RSV prefusion F (bivalent: subgroup A and B) System: CHO cells | Recombinant protein | 60 mcg each antigen (120 mcg total) |
Adjuvants
None listed on the package insert for this product (common for live attenuated and some inactivated whole-virus vaccines).
Preservatives
- None — Single-dose presentation; label states no preservative.
Excipients & residuals
| Ingredient | Category | Amount | Role |
|---|---|---|---|
| Tromethamine / tromethamine hydrochloride | Buffer | label quantity | buffer |
| Sucrose | Stabilizer | label quantity | stabilizer |
| Mannitol | Stabilizer | label quantity | stabilizer |
| Polysorbate 80 | Surfactant | label quantity | surfactant |
| Sodium chloride | Buffer | label quantity | tonicity |
Unadjuvanted protein subunit RSV vaccine (contrast Arexvy AS01E).
Source: FDA package insert · Verified 2026-07-09
ⓘ How to read this section
Ingredient lists are sourced from official package inserts for the specific brands named above. Formulations can change between lots and over time — verify against the current label before any clinical decision. Presence of a substance does not by itself indicate harm; toxicology is dose-, route-, and context-dependent. Browse the full ingredient database: Vaccine Ingredients index.
Causality assessment & potential mechanisms
Conditions below combine WHO-style causality levels with potential biological mechanisms from the site mechanism catalog (ae_mechanisms_catalog.json). HRSA VICP table listing (where shown) indicates a compensable temporal association under U.S. program rules — not automatic proof of causation for every case. Mechanisms are hypothesis-level pathways with graded evidence.
| Condition | Time window | Causality | Potential mechanism(s) |
|---|---|---|---|
| Anaphylaxis | 0–1 days |
Very likely / Probable
Evidence: High |
IgE-mediated hypersensitivity (anaphylaxis) (primary · hypersensitivity) Pre-existing or newly formed IgE against vaccine antigens or excipients (e.g., gelatin, egg proteins, PEG, polysorbate) triggers mast-cell and basophil degranulation with systemic mediator release. |
| Local/systemic reactogenicity | 0–3 days |
Very likely / Probable
Evidence: High |
Adjuvant-driven local and systemic reactogenicity (primary · innate_inflammation) Aluminum or other adjuvants (e.g., AS01B) amplify innate immune signaling, producing injection-site inflammation and transient systemic symptoms (fever, myalgia, fatigue). |
| Guillain-Barré Syndrome | 0–42 days |
Possible
Evidence: Low |
Molecular mimicry → Guillain-Barré syndrome (primary · molecular_mimicry) Vaccine- or infection-triggered immune responses cross-react with peripheral-nerve gangliosides or myelin components, producing demyelinating or axonal polyneuropathy. Temporal association — mechanism unknown (alternative · unknown) Reports show temporal clustering after vaccination but a specific pathogenic pathway is not established; alternative (coincidental) explanations remain plausible. |
| SIRVA | 0–2 days |
Very likely / Probable
Evidence: High |
SIRVA — incorrect injection into shoulder structures (primary · procedural) Needle placement into the subdeltoid/subacromial bursa or joint rather than deltoid muscle causes prolonged local inflammation and restricted range of motion (procedural, not antigen-specific). |
Framework: WHO causality + HRSA VICP (where applicable) + AE mechanism catalog.
Last updated: 2026-07-18.
Schema: schemas/vaccine_injury_table.schema.json
· Mechanisms: schemas/ae_mechanism.schema.json.
Not medical or legal advice.
Rank-aggregated VAERS signal detection (rankv)
No pairs mapping to this product family appear in the rank-aggregated common-signal set from rankv (intersection of GPS, PRR, ROR, and BCPNN signals). That does not mean absence of all VAERS reports — only that no pair met the four-method consensus filter in the published pipeline.
- Methods combined: BCPNN (IC), GPS/EBGM, PRR, ROR — then rank aggregation.
- Data: ~30 years of public VAERS (rankv processed tables).
- Origin: precisionFDA “Gaining New Insights by Detecting Adverse Event Anomalies” challenge solution.
- Caveat: Disproportionality signals are statistical associations in spontaneous reports. They do not establish causality, incidence, or product defect. Many top pairs reflect administration/product-use coding rather than clinical injury.
Source: nanx.me/rankv · Code: github.com/nanxstats/rankv (MIT) · Built: 2026-07-30.
2. Pre-Licensure Clinical Trial Data
Licensure trial design (ICAN / OpenVAERS)
This vaccine is not listed in ICAN’s childhood-schedule No Placebo Table (which covers CDC routine pediatric injectable products). Pre-licensure trial comparators for travel, adult, or specialty vaccines should be taken from FDA review documents and product labels in the sections below.
Source: OpenVAERS — No Placebo Table · ICAN original PDF · Attribution: Informed Consent Action Network (ICAN) via OpenVAERS · Last fetched: 2026-07-16. For many trials listing '6 months' safety review, ICAN notes review was typically ~30 days post-injection with a phone call at 6 months.
| Product | Pivotal evidence | Common reactogenicity (trials) |
|---|---|---|
| Arexvy (AReSVi-006) | ~82–89% efficacy vs. RSV-LRTD in adults ≥60 over one season | Injection-site pain, fatigue, myalgia, headache, arthralgia |
| Abrysvo (MATISSE maternal) | ~82% efficacy vs. severe RSV disease in infants through 90 days when given in pregnancy | Maternal: injection-site pain, headache, myalgia; infant outcomes monitored in trials |
| Beyfortus (HARMONIE / MELODY) | ~74–80% reduction in medically attended RSV LRTI in infants | Rash, injection-site reactions (mAb, not live virus) |
Trial efficacy is against RSV disease endpoints — distinct from VAERS adverse-event report counts post-licensure.
3. Post-Licensure Safety Data
RSV preventives licensed in 2023–2024; post-marketing databases are still accumulating. Guillain-Barré syndrome signal monitoring was highlighted in FDA communications for older-adult RSV vaccines — see primary FDA reviews for context.
⚠ Critical Caveat
VAERS reports are unverified temporal associations. High report volume for new products partly reflects stimulated reporting and large rollout scale.
Passive Surveillance: AE Type Breakdown (Multi-System)
Side-by-side view of U.S. VAERS, Health Canada Canada Vigilance, Japan JADER (PMDA), EU EudraVigilance, and live-scraped international systems via SurVigilance (VigiAccess, Lareb, DAEN, DMA, Medsafe). SurVigilance panels show MedDRA PT mention totals (not individual-case counts). Category assignment uses keyword matching — approximate, not official SOC coding. VAERS ZIP CAPTCHA downloads use this site’s vaers_pipeline.py; FAERS is bulk quarterly ZIP via SurVigilance (not product search).
VAERS (United States)
No VAERS category summary is mapped for this vaccine page.
Canada Vigilance (Canada)
No matching vaccine reports in the current Canada Vigilance extract.
JADER (PMDA, Japan)
No matching vaccine reports in the current JADER public extract.
EudraVigilance (EU)
No matching vaccine cases in the current EudraVigilance DAP export.
SurVigilance: VigiAccess · Lareb · DAEN · DMA · Medsafe
VigiAccess (WHO)
No VigiAccess (WHO) data yet — run python scrape_survigilance_one.py vigiaccess <vaccine-id> or python survigilance_pipeline.py --system vigiaccess (SurVigilance + direct scrapers: GitHub).
Lareb (Netherlands)
No Lareb (Netherlands) data yet — run python scrape_survigilance_one.py lareb <vaccine-id> or python survigilance_pipeline.py --system lareb (SurVigilance + direct scrapers: GitHub).
DAEN (Australia)
No DAEN (Australia) data yet — run python scrape_survigilance_one.py daen <vaccine-id> or python survigilance_pipeline.py --system daen (SurVigilance + direct scrapers: GitHub).
DMA (Denmark)
Denmark DMA interactive ADR search is currently offline (Danish Medicines Agency IT transition; public overviews frozen at 12 Mar 2024). Live product PT tables cannot be retrieved until DKMA restores the search. See DKMA notice. Denmark continues to report into EU EudraVigilance (panel above).
Medsafe (New Zealand)
Compare AE patterns across all vaccines →
VAERS Lot-Level Reports
2,808 VAERS reports with usable lot data (U.S.). Signal flags are hypothesis-generating only — not proof of an unsafe lot. Full dashboard →
4. Disease Prevention Context
RSV causes an estimated 58,000–80,000 hospitalizations and 100–300 deaths annually among U.S. children <5 years (prevention era), and substantial burden in adults ≥65. Seasonal immunization and infant mAb programs aim to reduce LRTI hospitalization — effectiveness in real-world settings is tracked separately from pharmacovigilance report counts.