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October 15, 2005


NEW SCIENTIST - Substantial commercial, political and bureaucratic barriers remain that will stop us being able to vaccinate enough of the world's people to contain any pandemic. What is urgently required is a global plan to combat the threat.

The problem boils down to numbers. A hybrid vaccine virus has already been produced that could immunize people against the H5N1 bird flu virus. But manufacturers can't make enough of it. Production capacity will not significantly increase any time soon, beyond a few new plants already under construction in Europe, and with the equipment available they can make only a few kilograms of the viral protein that forms the basis of the vaccine. If each dose contains 15 micrograms of viral protein, as in vaccines against ordinary flu, that's enough for no more than 900 million doses of vaccine over a normal six-month production cycle.

But that doesn't mean 900 million people can be protected. Because H5N1 is new to our immune system, people will need two vaccinations a few weeks apart. That halves the number who can be protected within six months to 450 million.

And even that is likely to be wildly optimistic. "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-g doses. That equates to enough vaccine worldwide for 75 million people, or around one quarter the US population.

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 Glaxo Smith Kline 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 g 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 immunized, 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. . .

Fedson, however, believes these barriers can be overcome. What is needed, he argues, is a well-funded international body along the lines of the Global Fund to Fight AIDS, Tuberculosis and Malaria, launched by the UN in 2002, which has spent $3 billion tackling these diseases. A similar body for pandemic flu, Fedson says, could coordinate vaccine development and fund the testing that will get us the low-dose, adjuvanted vaccine that may be needed to fight a global pandemic. "Wouldn't it be horrible if a pandemic comes and afterwards we discover we could have made far more vaccine?" he says. "We'll look like fools."

Such a body could also head off the political crisis that would ensue if vaccine-manufacturing countries decide to immunize their own people before allowing vaccine to be exported. "Can you imagine the conflict that would result if people in Bordeaux get vaccinated and people in Barcelona don't?" says Fedson. . .

"We are confident that a vaccine is feasible even if it is not fully matched to the pandemic strain, as long as there is a strong adjuvant," Giuseppe del Giudice of Chiron told New Scientist. While it may not protect 100 per cent, it might mean that H5 does not kill so many people. And it would act as a "priming" dose, meaning people would later require only one shot of vaccine matched to the pandemic strain.

The science is in place. Now the world needs to push forward to test and license a vaccine. When pandemic fears surfaced with swine flu in 1976, the US government developed, tested and licensed a vaccine, then made enough for most of its people, within six months. "We did it in 1976," says Fedson. "Why can't we do it now?"

Posted by dymaxion at October 15, 2005 07:29 AM

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