THE NATION : More proof that H1N1 targets young

At least 22 million Americans have contracted pandemic H1N1 influenza since the outbreak began in April and 3,900 have died, including about 540 children, according to new estimates from the Centers for Disease Control and Prevention. The numbers confirm what officials have been saying all along -- that swine flu is a young person’s disease.

The total is about three times the number of deaths that the agency has been reporting, but the previous figures were based on laboratory-confirmed cases, whereas the new number reflects agency epidemiologists’ best estimate of the total.

The new death toll is compiled in the same manner used for estimating deaths from seasonal flu, and gives a better comparison to those numbers. The numbers suggest that the toll from swine flu may approach that normally associated with seasonal flu. In a typical flu season, about 35,000 Americans die from influenza and related causes.

The estimates are compiled from both the number of laboratory-confirmed cases and from cases that may be listed on death certificates as pneumonia, organ failure or other infections, but which were precipitated by flu.

The new estimate does not mean that swine flu is worse than previously thought, simply that the CDC is getting a better handle on the situation. The previous numbers were “potentially giving an incomplete story of the pandemic,” Dr. Anne Schuchat, director of the CDC’s National Center for Immunization and Respiratory Diseases, said at a Thursday news conference. “What we are really trying to do is give a bigger picture.”

To compile the estimates, researchers use comprehensive data from 62 counties in 10 states, including deaths outside hospitalizations in which laboratory confirmation did not occur; a fraction of deaths in which lab tests were negative (the tests give as many as 40% false negatives); and a variety of other data. The results are then extrapolated to the country at large.

CDC estimated that:

* 8 million children up to age 17 were stricken by swine flu; 36,000 were hospitalized; and 540 died.

* 12 million adults ages 18 to 64 were infected; 53,000 were hospitalized; and 2,900 died.

* 2 million people 65 or older were infected; 9,000 were hospitalized; and 440 died. In a normal flu season, 90% of deaths occur in those over 65.

The new estimates do not include infections and deaths since Oct. 17, a period in which swine flu has been circulating at its highest rate. Schuchat said the agency would provide updates every three to four weeks.

She said that 41.6 million doses of swine flu vaccine were available Thursday, “not as much as we have hoped to have by today.” About 94 million doses of seasonal flu vaccine have been distributed, 3 million more than last week.

Food and Drug Administration Commissioner Dr. Margaret Hamburg said at the Reuters Health Summit in New York, however, that she expected to see the supply of swine flu vaccine improve soon.

“The gap between need and availability is narrowing,” she said. “I think we are going to see doses coming off the lines and into people’s arms or noses on a regular basis now.”

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thomas.maugh@latimes.com