Angola's yellow fever outbreak exposes vaccine supply dilemma

Some experts have called for a radical switch in strategy touse just one-tenth of the usual vaccine dose to conserve scarcestocks but the World Health Organization (WHO) says it can't besure this would work.

• Yellow fever outbreak kills 21 in Congo, WHO says

Most patients improve and their symptoms disappear after 3 to 4 days, according to the World Health Organization.

But death rates from yellow fever as high as 75 per cent in severecases requiring admission to hospital.

The condition, which takes its name from the jaundicedcolour of some patients, has spread to the Democratic Republicof Congo and there is concern it could gain a foothold for thefirst time in Asia.

The WHO says cases of yellow fever imported into China,which has close commercial ties with oil-rich Angola, show that"this outbreak constitutes a potential threat for the entireworld."

Low-dose vaccine proposed

Adding to the problem is the complicated process of makingyellow fever vaccine, which means there is no quick way to boostsupplies. Manufacturers, including the Institut Pasteur,government factories in Brazil and Russia, and French drugmakerSanofi, use a time-consuming method involving sterile chickeneggs.

"We need to get a low-dose vaccine authorized as soon aspossible because if we keep using full doses we will never catchup," he said.

The WHO, however, is not convinced. A spokesman said moreresearch was needed to measure immune response in children andduration of protection. The availability of suitable syringesfor delivering a smaller dose was also a limiting factor, hesaid.