Yellow fever vaccine is a vaccine that protects against yellow fever. Yellow fever is a viral infection that occurs in Africa and South America. Most people begin to develop immunity within ten days and 99 percent are protected within one month of vaccination, and this appears to be lifelong. The vaccine can be used to control outbreaks of disease. It is given either by injection into a muscle or just under the skin.

The World Health Organization (WHO) recommends routine immunization in all countries where the disease is common. This should typically occur between nine and twelve months of age.Those traveling to areas where the disease occurs should also be immunized. Additional doses after the first are generally not needed.

The yellow fever vaccine is generally safe. This includes those with HIV infection but without symptoms. Mild side effects may include headache, muscle pains, pain at the injection site, fever, and rash. Severe allergies occur in about eight per million doses, serious neurological problems occur in about four per million doses, and organ failure occurs in about three per million doses. It appear to be safe in pregnancy and therefore recommended among those who will be potentially exposed. It should not be given to those with very poor immune function.