AsianScientist (Jun. 26, 2012) – A new study reports that the 2009 pandemic H1N1 flu may have killed as many as half a million people around the world.
In a new report published today in The Lancet Infectious Diseases, researchers from the Centers for Disease Control and Prevention (CDC) estimate that the true number of deaths that took place during the pandemic from April 2009 through August 2010 was in a range of 151,700 to 575,400.
The average figure is fifteen times higher than the 18,500 laboratory-confirmed deaths reported to the World Health Organization.
“This is a better approximation of the number of deaths that occurred,” said researcher Dr. Marc-Alain Widdowson from the influenza division at the CDC.
“This study also confirms that the majority of deaths were in the under-65s, which is very different than seasonal influenza, where the vast majority of deaths are in the over 65s,” he added.
As a rule, the number of laboratory-confirmed deaths from any disease outbreak is assumed to underestimate the actual deaths. This could be due to the lack of diagnostic and treatment facilities in these areas, which mean that fewer patients are tested for the flu, and fewer deaths are attributed to the flu, Widdowson explained.
Hence, the authors believed that regions in Southeast Asia and Africa, where 51 percent of the deaths may have occurred, were more affected than official numbers suggest.
To get a better estimate of the actual number of H1N1-related deaths, the researchers created a model drawing on data from 12 high-, middle- and low-income countries, accounting for regional differences and income levels. Researchers also included data on lower respiratory tract infection mortality rates from the World Health Organization to assess health differences across countries.
In an accompanying comment by Dr. Cecile Viboud of the National Institutes of Health and Lone Simonsen of George Washington University, they noted that the method used to calculate the deaths has not been used before and contained uncertainties.
These findings were also based on those countries that collect data on the number of people who get the flu and die from it. The lack of accuracy in the data from low- and medium-income countries accounted for the wide variation in the estimate, they explained.
“These results are likely to be refined as more studies from low-income and middle-income regions become available, particularly from China and India, where about a third of the world’s population live but where little information is available about the burden of influenza,” Viboud said.
The article can be found at: Dawood FS et al. (2012) Estimated global mortality associated with the first 12 months of 2009 pandemic influenza A H1N1 virus circulation: a modelling study.
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