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Vaccine failure could lead to flu pandemic
Robin McKie, science editor
Sunday October 9, 2005
The Observer
Prospects of providing protection against the expected global outbreak of avian flu have been dashed by US researchers. They have found that only massive doses of vaccine are likely to protect individuals against the disease. As a result, manufacturing plants would strain to make even meagre supplies for a small number of people, doctors have warned.
'There is now a tremendous anxiety among scientists - including me - about this,' said bioprocessing expert Professor Peter Dunnill, chairman of the Advanced Centre for Biochemical Engineering at University College, London. 'Instead of providing protection for up to a billion people across the world, we will be lucky to get enough doses to vaccinate a few dozen million.
'That is not going to halt this virus if it gets into the human population. The problem is that the science of vaccines is great but the technology for their manufacture is lousy.'
At present, millions of chickens and other poultry are known to be infected with a deadly strain of flu virus known as H5N1. People who have picked up the virus from these birds have become seriously ill and in some cases have died. Doctors and scientists now fear a version that could be passed from human to human could soon evolve from avian H5N1. The result would be a deadly flu pandemic, one that would rival the 1918 outbreak of the disease which killed more than 20 million people.
Two medicines have been put forward as key defences against the outbreak. The first, the anti-viral medicine Tamiflu, which blocks the flu virus's growth within the body, could protect key workers - doctors, nurses, transport staff and police - when the disease strikes Britain. Supplies of Tamiflu are limited, however.
Instead, the main line of defence would be to rely on injecting people with a vaccine - based on a crippled version of the H5N1 virus - to boost immune defences in preparation of future infection.
But a new study by the National Institute of Allergy and Infectious Disease in Bethesda, Maryland, has dashed these prospects. Scientists at the institute used a vaccine made to combat the H5N1 avian flu virus and tested various concentrations on 452 healthy adults.
Only those who received the maximum dose - two shots of 90 micrograms of vaccine - were protected. 'This is the worst-case scenario,' James Robertson, of the UK National Institutes for Biological Standards and Control, told Nature. 'You are not going to get far with that.'
At present, the world has the capacity to manufacture about 900 million doses of flu vaccine a year at drug plants round the globe. But these vaccines are designed to target existing flu strains. Only a single dose of 15 micrograms is required for these.
Professor Ian Jones, of Reading University said: 'It is possible we could improve dosage levels but legal disputes over manufacturing rights, problems of scaling up manufacturing, arguments about who owns vaccines made in a given country and many other problems will also affect vaccine manufacture. We will be lucky to get enough vaccine to protect the public against avian flu in the next five years. We should therefore be quite clear: the chances of stopping a flu pandemic before 2010 are going to be extremely slim.'
Scientists do however point out that a human version of H5N1 could still fail to emerge. The virus could remain isolated in bird populations, weakening over the years until it poses no risk to humanity. 'It is a possibility but do we want to do nothing and hope for the best given the stakes?' added Jones.
Instead, scientists are now pressing that more radical solutions be sought. 'The current vaccine system is not going to work,' said Dunnill. 'We need a new approach.'
Robin McKie, science editor
Sunday October 9, 2005
The Observer
Prospects of providing protection against the expected global outbreak of avian flu have been dashed by US researchers. They have found that only massive doses of vaccine are likely to protect individuals against the disease. As a result, manufacturing plants would strain to make even meagre supplies for a small number of people, doctors have warned.
'There is now a tremendous anxiety among scientists - including me - about this,' said bioprocessing expert Professor Peter Dunnill, chairman of the Advanced Centre for Biochemical Engineering at University College, London. 'Instead of providing protection for up to a billion people across the world, we will be lucky to get enough doses to vaccinate a few dozen million.
'That is not going to halt this virus if it gets into the human population. The problem is that the science of vaccines is great but the technology for their manufacture is lousy.'
At present, millions of chickens and other poultry are known to be infected with a deadly strain of flu virus known as H5N1. People who have picked up the virus from these birds have become seriously ill and in some cases have died. Doctors and scientists now fear a version that could be passed from human to human could soon evolve from avian H5N1. The result would be a deadly flu pandemic, one that would rival the 1918 outbreak of the disease which killed more than 20 million people.
Two medicines have been put forward as key defences against the outbreak. The first, the anti-viral medicine Tamiflu, which blocks the flu virus's growth within the body, could protect key workers - doctors, nurses, transport staff and police - when the disease strikes Britain. Supplies of Tamiflu are limited, however.
Instead, the main line of defence would be to rely on injecting people with a vaccine - based on a crippled version of the H5N1 virus - to boost immune defences in preparation of future infection.
But a new study by the National Institute of Allergy and Infectious Disease in Bethesda, Maryland, has dashed these prospects. Scientists at the institute used a vaccine made to combat the H5N1 avian flu virus and tested various concentrations on 452 healthy adults.
Only those who received the maximum dose - two shots of 90 micrograms of vaccine - were protected. 'This is the worst-case scenario,' James Robertson, of the UK National Institutes for Biological Standards and Control, told Nature. 'You are not going to get far with that.'
At present, the world has the capacity to manufacture about 900 million doses of flu vaccine a year at drug plants round the globe. But these vaccines are designed to target existing flu strains. Only a single dose of 15 micrograms is required for these.
Professor Ian Jones, of Reading University said: 'It is possible we could improve dosage levels but legal disputes over manufacturing rights, problems of scaling up manufacturing, arguments about who owns vaccines made in a given country and many other problems will also affect vaccine manufacture. We will be lucky to get enough vaccine to protect the public against avian flu in the next five years. We should therefore be quite clear: the chances of stopping a flu pandemic before 2010 are going to be extremely slim.'
Scientists do however point out that a human version of H5N1 could still fail to emerge. The virus could remain isolated in bird populations, weakening over the years until it poses no risk to humanity. 'It is a possibility but do we want to do nothing and hope for the best given the stakes?' added Jones.
Instead, scientists are now pressing that more radical solutions be sought. 'The current vaccine system is not going to work,' said Dunnill. 'We need a new approach.'
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