Global Alert and Response (GAR)

WHO Report on Global Surveillance of Epidemic-prone Infectious Diseases - Yellow fever


Immunization is the single most important measure for preventing yellow fever. In populations where vaccination coverage is low, vigilant surveillance is critical for prompt recognition and rapid control of outbreaks. Mosquito control measures can be used to prevent virus transmission until vaccination has taken effect.

Yellow fever vaccine is safe and highly effective. The protective effect (immunity) occurs within one week in 95% of people vaccinated. A single dose of vaccine provides protection for 10 years and probably for life. Immunization with yellow fever vaccine can and should be part of the routine immunization system (administered during the same visit as measles vaccine). In addition, preventive immunization can be done in mass "catch-up" campaigns to increase immunization coverage in areas where it is low. This is often done on an emergency basis after the beginning of an outbreak. WHO strongly recommends routine childhood vaccination, which includes yellow fever. This is more cost effective and prevents more cases (and deaths) than emergency immunization campaigns to control an epidemic. Mosquito control measures can also play a role in reducing the risk of yellow fever, but are not as effective as immunization.