November 06, 2005

Bird flu: kick-start vaccination or face the consequences

A test vaccine has been produced already for the avian flu but can we make enough of it in time for a global pandemic?
"This virus has done a number on us," says Robert Webster of St Jude Children's Research Hospital in Memphis, Tennessee. In August, human trials of the hybrid vaccine showed that each person would require two 90-ìg doses. That equates to enough vaccine worldwide for 75 million people, or around one quarter the US population.
There's a way to boost the number of people who could be vaccinated but the US trials didn't use the method:
The way round this, say vaccine experts, is to boost the power of the shots by combining them with a simple immunity-stimulating chemical called an adjuvant. Norbert Hehme at vaccine maker GlaxoSmithKline in Dresden, Germany, has made a vaccine that can induce full immunity against relatives of the H5 family of bird flu viruses with two doses of just 1.9 ìg each.

Given existing production capacity for H5N1, this would allow 3.5 billion people to be protected. That is as many as could practically be immunised, given other limitations, says David Fedson, founder of the vaccine industry's pandemic task force. But the US trials did not use adjuvant, despite warnings that without it only large doses would work (New Scientist, 26 March, p 10).


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