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Rate of death linked to H1N1 15 times higher than previously confirmed
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Researchers from the CDC estimate that the rate of death associated with the 2009 pandemic influenza A H1N1 was actually 15 times higher than the reported laboratory-confirmed deaths.
“This study is one of the first to provide a global estimate of deaths caused by the 2009 H1N1 virus,” Fatimah Dawood, MD, of the CDC, told Infectious Disease News. “Unlike most other mortality estimates for the 2009 pandemic, this study includes estimated mortality for countries in Southeast Asia and Africa, where surveillance data on influenza-associated mortality are limited.”
Fatimah Dawood
According to the researchers, most mortality rates associated with the pandemic influenza A H1N1 are from high-income countries. The researchers sought out to estimate the global mortality and the number of years of life lost. They estimated the 12-month cumulative symptomatic attack rate across low-income, middle-income and high-income countries and multiplied it by the estimated symptomatic case fatality ratio from high-income countries. They stratified the results into three age groups: 0 to 17 years, 18 to 64 years and older than 64 years.
“We estimate that 80% of deaths during the first year that the 2009 H1N1 virus circulated were in people younger than 65 years of age, which is in stark contrast to typical influenza epidemics, during which the majority of deaths occur in persons aged 65 years and older,” Dawood said. “Because the 2009 pandemic affected younger populations more than older populations, we estimate that the global burden in terms of years of life lost was higher during this pandemic than it would be for a typical influenza season.”
The median estimate of country-specific respiratory deaths was 201,200, which was more than 10 times the number of global deaths reported to WHO from April 2009 to August 2010. Of these deaths, 29% occurred in the African region, where the estimated mortality rate was two to four times higher than in other countries. Of the deaths, 65% were among those aged 18 to 64 years and 13% were among those aged at least 64 years.
The researchers estimated an additional 83,300 cardiovascular deaths associated with the 2009 pandemic influenza A H1N1 among those aged older than 17 years. With the inclusion of cardiovascular deaths, the mortality rate in Africa remained two to three times higher than elsewhere. There was an estimated 9,707,000 years of life lost in the pandemic, with the Southeast Asia region experiencing the greatest number of years of life lost.
“These findings underscore the importance of influenza prevention measures such as influenza vaccines and emphasize the need to continue to improve the global response to future influenza pandemics by improving delivery of influenza prevention measures to regions of the world that may suffer more deaths,” Dawood said.
References:
Dawood FS. Lancet Infect Dis. 2012;doi:10.1016/S1473-3099(12)70121-4.
Disclosures:
Dr. Dawood reports no relevant financial disclosures.
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