17 May 2013 -- The yellow fever ‘booster’ vaccination given ten years after the initial vaccination is not necessary. WHO’s Strategic Advisory Group of Experts on immunization (SAGE) has reviewed the latest evidence and concluded that a single dose of vaccination is sufficient to confer life-long immunity against yellow fever disease. This information is crucial for countries where yellow fever is endemic, because it will allow them to reconsider their vaccine scheduling. It is also important for travellers.