The initial doses of bird flu vaccines that were stockpiled by US authorities are less effective now - they lose their strength over time. As the vaccines have a shorter 'shelf-life' than was first expected, it is possible that the US stockpile would now cover one million fewer people than previously thought.
In other words - as the vaccines have a shorter shelf-life than we had previously thought, many of the first ones that were bought may now not be so good.
(Shelf life = How long a drug can be kept/stored before it has to be thrown away. A bit like 'expiry date' on foods. If a drug has a two-year shelf life and was made on 1 January, 2007, it must be discarded by the end of 2008.)
Authorities may have to re-think their contingency plans. It was first thought that by having large stocks of H5N1 vaccines, a nation would be better prepared against a possible pandemic by vaccinating health workers, key personnel and other high-risk groups.
Even so, authorities stressed that the loss of strength is gradual, not total. It does not mean that the strength of the oldest vaccines in stock have gone down from 100 to zero.
Novartis Wins Contract To Top Up USA H5N1 Vaccine Stockpile
Novartis has been awarded a $40.95 million contract to top up the USA's bird flu vaccine stockpile. US authorities aim to have enough vaccines to cover 20 million people. Last year Novartis was awarded a $62.5 million contract.
The pre-pandemic egg-based vaccine will be manufactured by Novartis in 2007 in Liverpool, UK.
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