Actual pandemic flu death toll was much higher in 2009

A research team consisting of more than 60 collaborators in 26 countries has estimated the global death toll from the 2009 outbreak of the H1N1 virus to be 10 times higher than the World Health Organization’s count, which was based on laboratory-confirmed cases of this flu.

The study suggests that the pandemic virus caused up to 203,000 respiratory deaths around the world.

“This study confirms that the H1N1 virus killed many more people globally than originally believed,” says lead author Lone Simonsen, PhD, a research professor in the Department of Global Health at the George Washington University School of Public Health and Health Services. “We also found that the mortality burden of this pandemic fell most heavily on younger people and those living in certain parts of the Americas.”

The World Health Organization (WHO), which funded this study, had reports of 18,449 laboratory-confirmed deaths from the 2009 flu pandemic, but that is widely regarded as a low number because it is based only on people with confirmed cases of H1N1. This study shows that the actual death toll was much higher than the official count because most infected people never got an H1N1 lab test.

The low number of confirmed deaths at least initially led many to label the subsequent public health response as excessive. Yet this study shows that the H1N1 virus, although not as lethal as the infamous Spanish flu virus, still represented a formidable foe-killing many more people around the globe than the original estimates.

In order to do this study, the team obtained weekly virology data from the WHO and actual mortality data from 21 countries accounting for about 35 percent of the world’s population. They used the information to estimate the number of respiratory deaths, which often occur when H1N1 gets into the lungs and causes pneumonia, in each of those 21 countries. They then used a novel statistical procedure to project those results to the rest of the countries in the world.

In addition to deaths caused by respiratory diseases, the H1N1 virus can also kill by exacerbating existing health problems. And in fact, this team found that when the H1N1 deaths due to cardiovascular disease and other causes are included, the 2009 pandemic toll might be as high as 400,000.

The team discovered that an estimated 62 to 85 percent of those who died in the 2009 pandemic were younger than age 65. That high death toll for younger people is in marked contrast to that caused by seasonal influenza, which mostly targets seniors.

Source: George Washington University, USA

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