Swine flu death rate similar to seasonal flu: expert

WASHINGTON Wed Sep 16, 2009 12:06pm EDT

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WASHINGTON (Reuters) - The death rate from the pandemic H1N1 swine flu is likely lower than earlier estimates, an expert in infectious diseases said on Wednesday.

New estimates suggest that the death rate compares to a moderate year of seasonal influenza, said Dr Marc Lipsitch of Harvard University.

"It's mildest in kids. That's one of the really good pieces of news in this pandemic," Lipsitch told a meeting of flu experts being held by the U.S. Institute of Medicine.

"Barring any changes in the virus, I think we can say we are in a category 1 pandemic. This has not become clear until fairly recently."

The Pandemic Severity Index set by the U.S. government has five categories of pandemic, with a category 1 being comparable to a seasonal flu epidemic.

Seasonal flu has a death rate of less than 0.1 percent -- but still manages to kill 250,000 to 500,000 people globally every year.

A category 5 pandemic would compare to the 1918 flu pandemic, which had an estimated death rate of 2 percent or more, and would kill tens of million of people.

Lipsitch took information from around the world on how many people had reported they had influenza-like illness, which may or may not actually be influenza; government reports of actual hospitalizations and confirmed deaths.

He came up with a range of mortality from swine flu, from 0.007 percent to 0.045 percent.

Either way, having new information about how many people were infected and did not become severely ill or die makes the pandemic look very mild, he said.

"The news is certainly better than it was in May and even better than it was at the beginning of August," Lipsitch said.

H1N1 swine flu was declared a pandemic in June after flashing around the world in six weeks. Experts all said a true death rate would not be clear for weeks because it is impossible to test every patient and because people with mild cases may never be diagnosed.

This lack of information made the epidemics in various countries and cities look worse at first than they actually were, Lipsitch said. People sick enough to be hospitalized are almost always tested first.

"Yes, there's been hype, but I don't think it's been an outrageous amount of hype," Lipsitch said.

Seasonal flu is usually far worse among the elderly, who make up 90 percent of the deaths every year. In contrast, this flu is attacking younger adults and older children, but they are not dying of it at the same rate as the elderly, Lipsitch said.

(Editing by Eric Beech)

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