Monday, May 30, 2005

Vietnamese bird flu vaccine effort withdrawn

The story of the Vietnamese human bird flu vaccine is a curious one. Vietnam has suffered serious economic loss in the current outbreak of bird flu and also had 76 human cases and 37 deaths. Experimental vaccines are in trial in the US and Canada, but there is no timeline for any product to be available. Thus the Vietnamese decision to make their own vaccine made sense, at least from their standpoint. WHO claims, however, that Vietnam had assured them it would not do so, and now it is reported Vietnam has formally agreed not to pursue a vaccine on its own, but to use a prototype seed strain of the virus provided by WHO.
[WHO flu Chief Klaus] Stohr said his agency had been prepared to raise formal objections with the Health Ministry in Hanoi after the head of the vaccine development project told The Washington Post that Vietnam was determined to develop a vaccine on its own.

The comments by Prof. Nguyen Thu Van, including the disclosure of plans to hold human trials by August, contradicted guarantees from Vietnamese officials that they would call off the endeavor, WHO officials said.

WHO researchers expressed concerns that material used to produce the vaccine strain could be contaminated by other viruses and that a breach of security in the laboratory could allow a more dangerous version of the bird flu virus to escape. (Alan Sipress, WaPo)
Three issues seem to be involved. One is that an H5N1 vaccine, when administered to someone co-infected with an easily transmissible human influenza virus could result in a disastrous reassortment of genes that would produce a pandemic strain. The process for producing the vaccine was also considered risky by some at WHO. The virus would be grown in monkey kidney cells and thus become adapted to primates. While the vaccine was being produced, workers could become infected and an epidemic start this way. Finally, concerns were expressed about security in the labs, although exactly what kind of problem this presents is unclear.

Some of these arguments seem plausible. On the other hand, it is hard not to sympathize with a country with essentially no available supply of antiviral medication and a legitimate suspicion that in the face of a pandemic they will be left unable to afford vaccines made by international drug companies. Both sides of this curious episode make sense.

Meanwhile the Chinese are claiming to have their own vaccine. I don't see Klaus Stohr writing them angry letters. I wonder what the difference is.