A new study published this week in the Lancet has estimated the death toll from 2009’s H1N1 pandemic to be fifteen times higher than originally reported by the WHO. While 18,000 deaths from the flu virus were confirmed in 2009, experts now believe as many as 500,000 may have died.
Researchers at the CDC developed a new model for estimating deaths from H1N1 using flu and death rate data from twelve countries. They explained that data scarcity, common in developing countries, may account for the discrepancy between the previous estimate and the new model. Because of limited access to laboratory testing in resource-scarce regions, underestimating of flu mortality is not unusual.
The study also found that the H1N1 virus affected certain demographic groups more than the seasonal flu. Unlike seasonal flu, which tends to disproportionately affect the elderly, 80 percent of H1N1 deaths occurred among adults under 65.
Moreover, 59 percent of deaths were in Africa and Southeast Asia, regions that account for only 38 percent of the world’s population. This is a huge increase from the original estimate that twelve percent of deaths occurred in this region.
By providing more accurate estimates, this study will help experts to better allocate vaccinations and treatment, and prepare for future outbreaks.
H1N1, originally called swine flu, is a type of influenza virus that causes respiratory symptoms similar to those of seasonal flu. The WHO declared a world-wide pandemic of H1N1 in 2009. While this pandemic was deadly, it killed far fewer than the 1918 Spanish flu pandemic, which is estimated to have caused 50 million deaths.
The CDC recommends annual flu vaccination, which includes protection against H1N1, as the best means to prevent flu.