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Swine flu no big deal? Look at years of life lost
31 March 2010 by Debora MacKenzie

AS THE dust settles from the swine flu pandemic, the notion that it was no worse than seasonal flu persists. But it seems that while the number of deaths in the US was comparable to a bad seasonal flu, swine flu claimed three times as many years of life because the victims were so young.

In Paris, France, this week, the Council of Europe held further hearings on allegations that health agencies "faked" the pandemic to make money on vaccines. Such accusations irk flu researcher Lone Simonsen of George Washington University in Bethesda, Maryland. "I got angry when I saw people trying to claim this was ordinary flu," she says, pointing out that official death tolls so far are "only the tip of the iceberg" as many flu deaths are not recognised as such.

Because better official counts of deaths due to swine flu will not be available for another two years, Simonsen turned to the number of deaths from "flu-like illness", which is measured in 122 US cities every year to gauge the severity of the flu season. She used the relationship between these deaths and all flu deaths in previous years to estimate total US flu-season deaths in 2009.

Her figure of 44,100 deaths is slightly less than for pre-2009 flu seasons that were caused by the worst non-pandemic virus, which she calculates killed 47,800 on average.

While seasonal flu deaths are in people aged 76 on average, the average age of people killed by swine flu was 37. So Simonsen also decided to calculate years of life lost to swine flu, a common measure for the impact of disease. She used the ages of people who died in 2009 and their life expectancy to calculate that the US lost nearly 2 million years of life to the pandemic - more than in the 1968 pandemic (see graph). By contrast, she calculates that 600,000 years of life are lost on average to seasonal flu. Her work appears in PLoS Currents: Influenza.

The pandemic is not over yet. With autumn, swine flu has now returned to the southern hemisphere. Simonsen warns that most people killed in the UK by the 1968 pandemic died in its second wave, and advises vaccination.

Preliminary Estimates of Mortality and Years of Life Lost Associated with the 2009 A/H1N1 Pandemic in the US and Comparison with Past Influenza Seasons
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