Yellow Fever Booster Vaccination Not Required

The yellow fever ‘booster’ vaccination given ten years after the initial vaccination is not necessary, according to the World Health Organisation (WHO).  

The WHO through its Strategic Advisory Group of Experts on immunisation (SAGE) has reviewed the evidence and concluded that a single dose of vaccination is sufficient to confer life long immunity against yellow fever disease.

A valid certificate of initial vaccination presented by arriving travellers should not be rejected on the grounds that more than ten years have passed since the date the vaccination became effective as stated on the certificate and that boosters or revaccination cannot be required.

Since yellow fever vaccination began in the 1930s, only 12 known cases of yellow fever post-vaccination have been identified, after 600 million doses have been dispensed. Evidence showed that among this small number of “vaccine failures”, all cases developed the disease within five years of vaccination. This demonstrates that immunity does not decrease with time.

Yellow fever is an acute viral haemorrhagic disease, transmitted by infected mosquitoes, that is endemic to 44 countries in tropical areas of Africa and the Americas. Infection with the virus causes varying degrees of disease, from mild symptoms to severe illness with bleeding and jaundice and fatal outcomes.

There are an estimated 200,000 cases of yellow fever worldwide each year.  About 15% of people infected with yellow fever progress to a severe form of the illness, and up to half of those will die, as there is no cure for yellow fever.  The treatment is aimed simply at reducing patients’ discomfort.

The vast majority of reported cases and deaths occur in sub-Saharan Africa.  In endemic regions of Africa, yellow fever natural immunity is acquired with age, putting children at highest risk of infection.  Over the past two decades, the number of yellow fever cases worldwide has increased due to declining population, immunity to infection, deforestation, urbanisation, population movements and climate change.

Vaccination is considered to be the most important and effective measure against yellow fever. Protective immunity develops within 30 days for 99% of people receiving the vaccination. For routine immunisation programmes in Africa, home to 31 of the 44 yellow-fever endemic countries, the vaccine costs about US$0.82 per dose.