Debate on H5N1 death rate and missed cases continues
Lisa Schnirring Staff Writer
Feb 24, 2012 (CIDRAP News) – Two leading voices on the potential threat of lab-modified H5N1 viruses laid out their arguments about the human H5N1 fatality rate and undetected cases today and yesterday, with one group claiming “millions” likely have been infected and the other group saying current World Health Organization (WHO) fatality-rate estimates are about right.
Here are the abstracts:
Seroevidence for H5N1 Influenza Infections in Humans: Meta-Analysis
“The prevalence of avian H5N1 influenza A infections in humans has not been definitively determined. Cases of H5N1 infection in humans confirmed by the World Health Organization (WHO) are fewer than 600 in number, with an overall case fatality rate of >50%. We hypothesize that the stringent criteria for confirmation of a human case of H5N1 by WHO does not account for a majority of infections, but rather, the select few hospitalized cases that are more likely to be severe and result in poor clinical outcome. Meta-analysis shows that 1 to 2% of more than 12,500 study participants from 20 studies had seroevidence for prior H5N1 infection. ”
doi: 10.1128/mBio.00045-12 24 February 2012 mBio vol. 3 no. 2 e00045-12
Osterholm MT, Kelley NS. 2012. Mammalian-transmissible H5N1 influenza: facts and perspective. mBio 3(2):e00045-12. doi:10.1128/mBio.00045-12.
Mammalian-Transmissible H5N1 Influenza: Facts and Perspective
Two recently submitted (but as yet unpublished) studies describe success in creating mutant isolates of H5N1 influenza A virus that can be transmitted via the respiratory route between ferrets; concern has been raised regarding human-to-human transmissibility of these or similar laboratory-generated influenza viruses. Furthermore, the potential release of methods used in these studies has engendered a great deal of controversy around publishing potential dual-use data and also has served as a catalyst for debates around the true case-fatality rate of H5N1 influenza and the capability of influenza vaccines and antivirals to impact any future unintentional or intentional release of H5N1 virus. In this report, we review available seroepidemiology data for H5N1 infection and discuss how case-finding strategies may influence the overall case-fatality rate reported by the WHO. We also provide information supporting the position that if an H5N1 influenza pandemic occurred, available medical countermeasures would have limited impact on the associated morbidity and mortality.
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