WHO says single yellow fever shot is enough

The World Health Organization says a yellow fever booster vaccination given 10 years after the initial shot isn't necessary.

The UN's global health agency said that its expert group on immunisation believes a single dose of vaccination is sufficient to confer lifelong immunity against the disease.

The Geneva-based body says only 12 known cases of yellow fever after vaccination have ever been identified. Some 600 million doses have been dispensed since yellow fever vaccination began in the 1930s.

Yellow fever is an acute viral hemorrhagic disease transmitted by infected mosquitoes that is endemic to 44 countries in tropical areas of Africa and the Americas.

There are an estimated 200 000 cases of yellow fever and up to 15 000 deaths worldwide each year.