In a study published on Monday in the Lancet Infectious Diseases, researchers from the Centers for Disease Control and Prevention (CDC) said the 2009 H1N1 swine flu pandemic likely killed about 284,500 people worldwide between August 2009 and August 2010, a number 15 times higher than the 18,500 deaths reported to the WHO, Bloomberg News reports. “More than half the deaths may have been in southeast Asia and Africa, compared with 12 percent of officially reported fatalities, the authors wrote,” the news agency states (Bennett, 6/25). The reported cases “were only the deaths confirmed by lab testing, which the WHO itself warned was a gross underestimate because the deaths of people without access to the health system go uncounted, and because the virus is not always detectable after a victim dies,” Reuters writes (Begley, 6/25).

The study authors used statistical modeling to estimate the number of H1N1-related deaths, which “could range anywhere from 151,700 to 575,400,” CNN’s “The Chart” blog notes. The researchers used three types of data in their analysis: “[t]he percentage of people who were sickened by H1N1 in 12 countries”; “[t]he proportion of people who got sick from H1N1 and then went on to die (data that was only available from five countries)”; and “[p]reviously published country-specific overall mortality rates,” the blog writes (Desai, 6/25). “The new numbers could be used ‘to improve the public health response during future pandemics in parts of the world that suffer more deaths, and to increase the public’s awareness of the importance of influenza prevention,’ said lead author Fatimah Dawood, a CDC epidemiologist,” MyHealthNewsDaily reports (6/25). The study is accompanied by a commentary by Cecile Viboud of the NIH and Lone Simonsen of the George Washington University School of Public Health and Health Services (6/26).