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Pharmacology · Viral vaccines

Yellow fever vaccine !

Live attenuated 17D virus. One dose gives lifelong protection. It is part of Colombia's national schedule and is free through the PAI.

Updated 2026-11-01

  • Class: Viral vaccines
  • Target: Yellow fever virus envelope protein (E)
  • ATC code: J07BL
  • WHO Model List of Essential Medicines

Also called: 17D vaccine, Antiamarílica (Spanish)

The figure shows the soluble envelope protein of the 17D vaccine strain in its prefusion state; neutralising antibodies target this protein.

Target in 3D: Yellow fever virus envelope protein (E). PDB structure 6IW4 (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

The 17D virus replicates weakly and induces neutralising antibodies against the envelope protein. Most people are protected within ten days and nearly all within a month. Because it is live, it is avoided in severe immunosuppression and thymus disorders, and caution is needed over age 60, when the rare serious neurological and viscerotropic reactions are more frequent.

  1. Attenuated 17D virus is injected and replicates weakly
  2. Neutralising antibodies form against the envelope protein
  3. Most are protected within ten days, nearly all within a month
  4. One dose gives lifelong immunity; no booster is needed

Pharmacokinetics

Onset and duration
Immunity in 80–100% of people within 10 days and over 99% within 30 days (WHO)

Indications

  • People living in or travelling to areas with yellow fever transmission (sylvatic cycle via Haemagogus and Sabethes mosquitoes, urban cycle via Aedes)
  • Colombia: part of the national schedule, free and without the «open vial» barrier, under the 2025 health emergency for yellow fever (Resolución 691 de 2025, MinSalud)
  • Proof of vaccination for international travel when a country requires it (International Health Regulations)

Adverse effects

Common

  • Headache, myalgia, low-grade fever in the days after the dose
  • Local pain

Contraindications

  • Young infants (very high risk of encephalitis)
  • Severe allergy to egg, chicken proteins, gelatin or another component
  • Thymus disorders with abnormal immune function (thymoma, myasthenia gravis)
  • Severe immunosuppression: symptomatic HIV or low CD4 count, immunosuppressive therapy, transplant, malignancy

Key interactions

MMR (triple viral)
Given together, responses to yellow fever and rubella can be lower; when possible they are separated by one month
Immunosuppressive therapy
Contraindicated: risk of serious vaccine-virus disease

What is monitored

  • Fever, headache, confusion or jaundice in the weeks after the dose (possible serious reaction)
  • Vaccination recorded on the national card and, for travel, the international certificate

Administration and safety

  • Reconstitute with the supplied diluent only
  • Subcutaneous route
  • Check age, immune status, thymus history and egg allergy before giving
  • Record it on the vaccination card and the international certificate when needed

Nursing care

  • Screen for egg allergy, immunosuppression, thymus disease and age over 60
  • Ask about breastfeeding of a young infant
  • Teach the warning signs: high fever, severe headache, confusion, jaundice
  • Teach mosquito bite prevention

Pregnancy and breastfeeding

Not recommended in pregnancy except during outbreaks, after weighing risk; vaccinating a woman who breastfeeds a young infant is avoided when possible, because the vaccine virus has caused encephalitis in breastfed newborns.

Test yourself

Think of the answer, then tap the question to see it.

Is a booster of yellow fever vaccine needed?

No: WHO states that a single dose gives lifelong immunity.

Which thymus history contraindicates yellow fever vaccine?

Thymus disorders with abnormal immune function, such as thymoma or myasthenia gravis.

What are YEL-AND and YEL-AVD?

Rare serious reactions to the live vaccine: neurological disease (YEL-AND) and multiorgan viscerotropic disease (YEL-AVD), both more frequent after age 60.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: Yellow fever (World Health Organization, 2025); Yellow Fever | CDC Yellow Book™ (Centers for Disease Control and Prevention, 2025); Lineamiento Técnico y Operativo de la Primera Jornada Nacional de Vacunación (Ministerio de Salud y Protección Social (Colombia), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.