1. Basic Information
Disease Overview
- Yellow Fever: Mosquito-borne flavivirus (Aedes and Haemagogus species vectors) endemic to 47 countries in sub-Saharan Africa and tropical South America. Most infections are mild or asymptomatic; roughly 15% progress to a severe "toxic phase" with jaundice, hemorrhage, and multi-organ failure. Case-fatality in the severe/toxic phase is 20–50%. WHO estimates ~200,000 cases and ~30,000 deaths annually worldwide, though true burden is likely underreported.
Recommended Use
| Population | Recommendation |
|---|---|
| Travelers ≥9 months to endemic areas | Single dose ≥10 days before travel |
| Required for IHR entry/transit | Many African and South American countries require proof of vaccination (International Certificate of Vaccination or Prophylaxis, "yellow card") for entry, especially from other endemic countries |
| Booster | WHO (2016) and CDC/ACIP concluded a single dose provides lifelong protection for most people; a booster is advised only for select groups (e.g., vaccinated during pregnancy, HIV infection, vaccinated before age 2, HSCT recipients) |
| Contraindicated | Infants <6 months, severe egg allergy (vaccine is egg-based), thymus disorder/thymectomy, symptomatic HIV or other significant immunosuppression |
Source: CDC Yellow Book; WHO Yellow Fever position paper (2013, reaffirmed 2016).
Licensed Products (U.S.)
- YF-VAX® (Sanofi) — live attenuated 17D-204 strain. Only vaccine licensed in the U.S.; administered exclusively at designated Yellow Fever Vaccination Centers.
- Stamaril® (Sanofi) — equivalent 17D-204 vaccine used outside the U.S.
Ingredients (Package Insert)
Structured composition for 1 branded product 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.
YF-VAX Sanofi Pasteur · Live attenuated
Delivery
Route: Subcutaneous (SC)
Form: Lyophilized powder (reconstitute)
Dose volume: 0.5 mL
Presentation: single-dose or multi-dose vial + sterile diluent (NaCl)
Encapsulation / delivery vehicle
None (no nanoparticle/VLP encapsulation system)
Antigens
| Antigen | Type | Amount / dose |
|---|---|---|
| Yellow fever virus (live, attenuated) Strain: 17D-204 · System: living avian leukosis virus-free chicken embryos | Live attenuated virus | ≥4.74 log10 PFU per 0.5 mL |
Adjuvants
None listed on the package insert for this product (common for live attenuated and some inactivated whole-virus vaccines).
Preservatives
- None — No preservative added.
Excipients & residuals
| Ingredient | Category | Amount | Role |
|---|---|---|---|
| Sorbitol | Stabilizer | stabilizer (label quantity) | stabilizer |
| Gelatin | Stabilizer | stabilizer (label quantity) | stabilizer |
| Egg protein | Residual (culture) | residual from chick embryo culture | residual — contraindicated in severe egg allergy |
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. |
| Yellow fever vaccine-associated viscerotropic disease (YEL-AVD) | 0–10 days |
Very likely / Probable
Evidence: High |
Yellow fever vaccine-associated viscerotropic disease (primary · live_replication) Rare multi-organ failure syndrome after live YF-17D vaccine, resembling wild-type yellow fever, with high case fatality; risk higher in older adults and thymectomy history. Uncontrolled live attenuated vaccine replication (contributing · live_replication) In immunocompromised or otherwise susceptible hosts, live attenuated vaccine strains can replicate beyond the intended limited infection, causing disseminated disease or organ-specific infection. |
| Yellow fever vaccine-associated neurologic disease (YEL-AND) | 0–30 days |
Very likely / Probable
Evidence: High |
Yellow fever vaccine-associated neurologic disease (primary · live_replication) Rare neurotropic disease after YF-17D (meningitis, encephalitis, GBS-like illness), more often reported in infants and older adults. Vaccine-strain encephalitis / encephalomyelitis (contributing · live_replication) Live viral vaccines can rarely cause CNS infection or demyelinating encephalomyelitis via direct viral invasion or post-infectious immune attack. |
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.
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.
The 17D strain was developed in the 1930s (Nobel Prize, 1951) and has been used in hundreds of millions of doses since. Modern licensure data rely on decades of immunogenicity studies rather than a single contemporary placebo-controlled efficacy trial, since a placebo trial would be unethical given established effectiveness and endemic disease severity.
| Metric | Data | Evidence Strength |
|---|---|---|
| Seroconversion after single dose | >90–99% by day 30 across studies | Strong |
| Durability of single-dose immunity | Neutralizing antibodies detected ≥30–40 years post-vaccination in long-term cohort studies; underpins 2016 WHO lifelong-protection policy | Strong |
| Randomized comparative safety trials | Limited; most safety data are observational/surveillance-based rather than from large modern RCTs | Limited |
Key Limitations
- No modern placebo-controlled efficacy trial: Effectiveness is inferred from immunogenicity (neutralizing antibody titers as a correlate of protection) and historical field experience, including outbreak-control campaigns, not a contemporary randomized clinical endpoint trial.
- Special-population data are sparse: Pregnant and breastfeeding people, and infants 6–8 months, are underrepresented in pre-licensure data; vaccination in these groups is generally deferred unless travel is unavoidable and risk is high.
3. Post-Licensure Safety Data
VAERS and Global Pharmacovigilance
Post-licensure surveillance since the late 1990s identified two rare but serious adverse event syndromes not apparent in earlier decades of use, prompting refined contraindications and age/risk-based precautions:
- Yellow Fever Vaccine-Associated Viscerotropic Disease (YEL-AVD): A multi-organ-failure syndrome resembling wild-type yellow fever, almost always after first-ever vaccination. Overall rate ~0.3–0.4 per 100,000 doses; substantially higher in people >60 years (~1–2.5 per 100,000) and those with thymus disorders.
- Yellow Fever Vaccine-Associated Neurologic Disease (YEL-AND): Encephalitis, Guillain-Barré syndrome, or other neurologic illness following vaccination. Rate ~0.8 per 100,000 doses overall; markedly higher in infants <9 months (historically up to several per 100,000, driving the age-6-months contraindication) and in adults >60 years.
- Anaphylaxis: Egg-based production means egg-allergic individuals are at elevated risk; skin testing/graded dosing protocols exist for those who must be vaccinated despite allergy history.
⚠ Critical Caveat
Because of YEL-AVD/YEL-AND risk being concentrated in first-time vaccinees over 60 and infants under 9 months, clinicians are advised to weigh individual destination risk against vaccine risk rather than vaccinating reflexively for any travel to an endemic country.
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)
Canada Vigilance (Canada)
JADER (PMDA, Japan)
EudraVigilance (EU)
3,791
individual cases · adrreports.eu DAP export (up to 28/06/2026)
Reaction SOC breakdown not included in this workbook export.
SurVigilance: VigiAccess · Lareb · DAEN · DMA · Medsafe
VigiAccess (WHO)
Lareb (Netherlands)
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)
4. Documented Adverse Events — Evidence of Association
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.
▶ Strong Evidence of Causal Association
- Injection site reactions, low-grade fever, headache, myalgia: Common, ~10–30% of recipients, self-limited (2–5 days). Strong
- YEL-AVD (viscerotropic disease): Rare (~0.3–0.4/100,000 doses overall; higher in first-time vaccinees >60y). Can be fatal (~60% case-fatality among confirmed cases). Strong
- YEL-AND (neurologic disease): Rare (~0.8/100,000 doses; higher in infants <9mo and adults >60y). Strong
- Anaphylaxis (egg-allergic individuals): Attributable to residual egg protein from production process. Strong
▶ Moderate or Preliminary Evidence
- Vaccination during pregnancy: Observational cohorts have not found a consistent signal for major birth defects, but data remain limited in volume; inadvertent vaccination during pregnancy is not considered an indication for termination. Limited
5. Disease Prevention Benefits
Outbreak Control Effectiveness
| Event | Outcome |
|---|---|
| Angola/DRC outbreak, 2016 | Largest urban yellow fever outbreak in decades (>7,000 suspected cases); mass vaccination campaigns (including fractional-dose strategy to stretch limited supply) brought transmission under control |
| Brazil, 2016–2019 | Sylvatic outbreak spread toward major cities; large-scale campaign vaccinated tens of millions, averting an urban re-establishment of transmission |
| Historical elimination | Mass vaccination in the mid-20th century eliminated urban (Aedes-driven) transmission from most of the Americas, though sylvatic (jungle) transmission persists |
Source: WHO Disease Outbreak News; PAHO epidemiological updates.
6. Evidence Summary
The 17D yellow fever vaccine is one of the most effective live vaccines ever developed, with a single dose providing lifelong protection for the great majority of recipients. Its main safety concern — rare but serious viscerotropic and neurologic disease, concentrated in first-time vaccinees over 60 and infants under 9 months — is well characterized and is now explicitly factored into age-based risk-benefit vaccination guidance rather than blanket recommendations.
| Domain | Evidence Grade | Key Finding |
|---|---|---|
| Immunogenicity/durability | Strong | Single dose, lifelong protection for most people |
| YEL-AVD | Strong | Rare, age- and first-dose-dependent, can be fatal |
| YEL-AND | Strong | Rare, elevated in infants <9mo and adults >60y |
| Pregnancy safety data | Limited | No consistent signal, but limited volume of data |
7. International Surveillance & Global Data
Quick links to public pharmacovigilance databases and trial registries relevant to Yellow Fever Vaccine. Reporting counts do not establish causality.
8. Curated Adverse Event Literature
Curated peer-reviewed literature linking specific adverse events to Yellow Fever Vaccine. Each entry is a case report, case series, or related safety publication identified via PubMed. Expand Search PubMed for additional literature below to run custom queries.
9. Key References
- WHO. Vaccines and vaccination against yellow fever: WHO position paper. Wkly Epidemiol Rec. 2013;88(27):269–284.
- CDC. Yellow Fever. CDC Yellow Book, Travelers’ Health. cdc.gov/yellowbook
- Staples JE, et al. Yellow Fever Vaccine: Recommendations of ACIP. MMWR Recomm Rep. 2010;59(RR-7):1–27.
- WHO. Fractional dose yellow fever vaccination as a dose-sparing strategy. who.int
- PAHO. Epidemiological Updates — Yellow Fever. paho.org