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Flu Vaccine Market Chaotic Years
January 10, 2005
>>Chiron Corp.'s forced departure in October from the flu vaccine market has turned upside down planning for the 2005-06 influenza season.
"This coming season is going to be difficult," said Len Lavenda, spokesman for Aventis Pasteur, one of only two companies besides Emeryville-based Chiron with a U.S. license to manufacture flu vaccine. "There are numerous scenarios that could play out."
The uncertainty is two-pronged. First, federal officials don't know which companies will be making vaccine. Second, they can't predict demand.
Accordingly, manufacturers that already have U.S. licenses don't know how much to make. And those who buy the vaccine aren't sure how much and from where they can order.<<
The above problems relate to manufacture of an FDA approved flu vaccine involving the two companies approved to sell the vaccine in the Unites States. The two manufacturers, Aventis Pasteur and Chiron are the same two companies working on a bird flu pandemic vaccine. Chiron is targeting vaccines against H5N1 and H9N2 while Aventis Pasteur is targeting H5N1.
The uncertainties surrounding the manufacture of a human vaccine dwarf potential problems with a pandemic vaccine. The human vaccine has been slowly changing, although the change in the H3N2 version may be accelerating. In the northern hemisphere Panama-like viruses had been used since 1999. This year Panama was replaced by Fujian-like. However, the virus has already changed, so the next vaccine for the southern hemisphere is Wellington.
On the avian flu front, a pandemic vaccine was made against the H5N1 that infected 18 and killed 6 in Hong Kong in 1997. However, that vaccine was not effective against the current H5N1 in Vietnam and Thailand. Thus, 2 million new doses are slated for trials which should be starting soon. However, H5N1 has been evolving much more rapidly than H3N2. This is due in part to the extreme genetic instability of H5N1 in Asia. H5N1 evolves via recombination, and each year new sequences fly into the region via migrating birds. The version from last year generated a high case fatality rate in Thailand and Vietnam.
Human cases have now been reported for this season in Vietnam. There have been 4 confirmed cases and 2 suspect cases in the Mekong Delta region. Three of the four confirmed cases have dies, and the fourth is in critical condition on a ventilator. The sequences of the current versions have not been made public yet, so it is hard to say how effective a vaccine against last years version will be. The virus has not achieved efficient human to human transmission, but flu ca be quite contagious, and could spread around the world in days.
Creating millions of doses of a well matched pandemic vaccine in response to a virus that has acquire efficient human to human transmission will be a major challenge.