As a rule, the number of laboratory-confirmed deaths from any disease outbreak is assumed to underestimate the actual deaths, since many people who get the disease are not tested or may not see a doctor or go to the hospital.
Applying this rule to the data, Widdowson's team estimated that the actual number of deaths from the pandemic H1N1 flu from April 2009 to August 2010 was between 151,700 and 575,400 across the globe.
Moreover, 80 percent of those who died were under 65, which is the reverse seen with usual seasonal flu, they noted.
And, they said, the flu was projected to have taken its greatest toll in southeast Asia and Africa, home to 38 percent of the world's population, where 51 percent of the deaths may have occurred.
Lone Simonsen, a research professor in the department of global health at George Washington University and co-author of an accompanying journal editorial, said, "This first estimate of the global mortality burden of the 2009 pandemic is an important study that confirms the impression that the laboratory-confirmed deaths had deeply underestimated the burden of this pandemic."
She cautioned, however, that the method used to calculate the deaths has not been used before and needs to be validated before the findings can be taken as gospel.
"Therefore, there is still uncertainty about the exact number of deaths in individual regions and countries," Simonsen added.
For more on the 2009 pandemic, visit the U.S. Centers for Disease Control and Prevention.
SOURCES: Marc-Alain Widdowson, VetMB, influenza division, U
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