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Yellow fever

Yellow fever is a mosquito‑borne viral disease endemic in tropical/subtropical regions of Africa and South America. Transmission to humans occurs primarily via the bite of infected mosquitoes.

Clinical Presentation and Diagnosis

Illness ranges from mild (fever, aches, pains) to severe with hepatic injury, hemorrhage and jaundice. Diagnosis uses compatible symptoms, epidemiologic exposure (travel/residence in risk areas), and laboratory testing.

Treatment and Prevention

No specific antivirals exist; care is supportive. Prevention relies on mosquito‑bite avoidance and vaccination where indicated.

Vaccine Recommendations

Vaccinate persons ≥9 months traveling to or living in risk areas in South America/Africa, and when entry requirements mandate proof (ICVP). Because serious adverse events can occur, vaccinate only if exposure risk or proof is required. Review contraindications and precautions before vaccination.

Administration and Blood Donation

Defer blood donation ≥2 weeks post‑vaccination; rare transfusion/transplant transmission has occurred.

Booster Doses and New Guidelines

ACIP (Feb 2015): a single dose provides long‑lasting protection for most travelers. Additional doses may be considered for: women vaccinated during pregnancy; recipients of hematopoietic stem‑cell transplant; persons with HIV; travelers vaccinated ≥10 years ago visiting high‑risk areas; laboratory workers handling wild‑type YF virus.

Contraindications

• Severe allergy to a vaccine component
• Age <6 months
• Symptomatic HIV or CD4 <200/mm³ (or <15% if <6 years)
• Thymus disorders with abnormal immune function
• Primary immunodeficiencies; malignant neoplasms; transplantation
• Immunosuppressive or immunomodulatory therapies

Precautions

• Age 6–8 months; age ≥60 years
• Asymptomatic HIV with CD4 200–499/mm³ (15–24% if <6 years)
• Pregnancy; breastfeeding

Coadministration with Other Vaccines

Inactivated vaccines: give any time relative to YF vaccine (including simultaneous).

Live viral vaccines: generally may be given simultaneously; if not, separate by 30 days. Coadministration with MMR is acceptable, but consider 30‑day spacing to optimize antibody responses.

Live bacterial vaccines: limited data suggest oral typhoid (Ty21a) and oral cholera (CVD103‑HgR) can be given at any interval.

Reactions to Vaccine

Usually mild (headache, myalgia, low‑grade fever). Rare but serious events include anaphylaxis, yellow fever vaccine‑associated viscerotropic disease (YEL‑AVD) and neurologic disease (YEL‑AND).

References: CDC – About Yellow Fever | CDC – Vaccine Guidance

Yellow Fever