Commentary
H5N1 Pre-Pandemic Vaccinations
Recombinomics Commentary 21:31
July 9, 2008
Unfortunately, the overall control picture is bleak.
Thailand, Vietnam and China have notched up successes in curbing outbreaks in birds, which is key to minimizing the chance that the virus can pass to humans.
But South Korea had its worst outbreak ever in April, and the disease has become endemic in Indonesia, Bangladesh, Vietnam and Egypt.
The Commentary on page 162 endorses what might be an intriguing adjunct: 'pre-pandemic' vaccines, which would be matched not to the exact pandemic strain, but to earlier variants.
Even if these vaccines were only partly effective, advocates argue, they might confer sufficient protection to prevent death or severe disease.
Although this idea is untested, it merits consideration — especially as strain-specific vaccines would be available only several months into the pandemic, and even then would be in very short supply.
The above comments in today’s Nature highlight the downward spiral of efforts to contain H5N1. Since its explosion out of China in late 2003, H5N1 has expanded its geographical reach to over 60 countries, most of which were due to the spread of H5N1 into Europe, the Middle East, and Africa. As noted above, the countries initially hit by H5N1 in late 2003 and early 2004 have fought a losing battle and H5N1 has been declared endemic in multiple Asian countries, and within the past week has been declared endemic in Egypt also.
A recent report on H5N1 from patients in Thailand has identified quasi-species with multiple receptor binding domain changes, including S227N, which has been reported in human cases in Turkey and Egypt in 2006 and 2007, as well as M230T. M230I has been linked to fatal cases in Egypt, while the vaccine resistant strain in Egypt and Israel has M230V. M230I is also in the clade 2.3.2 sequences in Japan, southeast Russia and presumably South Korea, where a soldier / culler has tested positive for H5. Human fatalities have been reported in Turkey, Iraq, Azerbaijan, and Egypt and receptor binding domain changes have been reported in all human outbreaks.
Thus, it has become increasingly clear that the spread and diversity of H5N1 will pose a significant challenge, and the implementation of a pre-pandemic vaccine to prime the world’s population has significant merit.
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