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Efficacy of H5N1 Vaccine in Qinghai China Unclear
May 28, 2005
>> "Experiments show the efficiency rate of the newly developed vaccines in preventing infection by the H5N1 virus is 100 percent," Chen Hualan, director of the China National Bird Flu Reference Laboratory,
was quoted as saying in an overnight report.
China's Ministry of Agriculture had given its approval, and a sales permit, for the vaccines, Xinhua said, without mentioning whether the treatments had been evaluated outside the country.
The agency said supplies of the new vaccines had already been sent to far-flung western Qinghai province, where China has been scrambling to contain its 1st breakout since late 2004, after 178 geese were
found dead of the H5N1 virus on 4 May 2005. <<
Although the vaccine may be 100% effective against the H5N1 used in testing, H5N1 is evolving, so efficacy against the H5N1 that has now killed over 1000 birds in Qinghai Lake Nature Reserve remains to be proven.
Several pieces of data suggest the H5N1 in Qinghai Lake has changed. Initial reports indicatd the geese were not dying of bird flu, suggesting the pathology was different. The number of reported birds continues to increase. The May 21 OIE report indicated at least 5 species of wild waterfowl had died, which is unprecedented. Now the number dead has more than doubled. The number of species involved has not been reported, but the H5N1 spread seems to be rapid and deadly.
The reports of human fatalities have also been without precedence. 121 deaths and 79 infections in 18 communities have been reported. Although blanket denials have been issued, the specific cases, some of whom were named, have not been addressed. No cause of death for these cases has been offered by China.
In addition, Qinghai Lake is located within the intersection of the East Asia and Central - South Asia flyways, so waterfowl from many locations in Asia intermingle, allowing for more dual infections leading to more recombination and more evolution.
The dead birds were initially discovered on May 4 and the lab results were available May 18. Therefore testing of the vaccine on the H5N1 in Qinghai Lake was not possible prior to shipment. Based on the presentation of the H5N1 infections, it seems unlikely that the H5N1 in Qinghai Lake will be closely related to the H5N1 previously found in China.
Thus, the efficacy of the current vaccine of the H5N1 in birds and/or people near Qinghai Lake remains to be demonstrated.