Children and obese hard hit by swine flu: experts

WASHINGTON (Reuters) - People who were morbidly obese and school-aged children were much more likely to become seriously ill or to die from H1N1 swine flu, U.S. experts said on Wednesday.

Preliminary data showed the morbidly obese had four times the rate of hospitalizations and deaths, while the death rate for children was five times higher than usual, experts at the U.S. Centers for Disease Control and Prevention said.

They are working up detailed studies of the pandemic in the United States, the CDC's Dr. Nancy Cox, Dr. Anne Schuchat and Dr. Lyn Finelli told a meeting of the Advisory Committee on Immunization Practices.

"We estimate that the deaths in children are probably five fold higher, at least, than what is usually seen in seasonal flu," Schuchat told the meeting.

Deaths among the elderly were about five times less than in a usual flu season, Schuchat added.

Earlier on Wednesday, the World Health Organization said it was too early to say the pandemic had peaked globally, although it has clearly waned in North America and Europe.

Cox said the pandemic version of H1N1 had clearly replaced its distant cousin, seasonal H1N1, this year.

WHO and advisers to the U.S. Food and Drug Administration chose this week to replace the seasonal H1N1 component in next season's flu vaccine with the swine flu strain.

But Cox said it is too soon to say H1N1 is just one of several circulating seasonal influenza strains.

"We have yet to see what would happen in the Southern Hemisphere. We would prefer not to jump the gun and say the 2009 H1N1 virus is a seasonal virus," she said.

TESTS DOWN

Results from Quest Diagnostics show the number of H1N1 positive tests have dropped 96 percent since the peak in early November.

"The report also finds that 99 percent of all flu tests are H1N1 positive," Quest wrote in a statement released on Wednesday.

The CDC estimates H1N1 has killed up to 17,000 people in the United States alone.

This compares to about 36,000 people killed every year by seasonal flu, but Finelli noted that it takes months to gather data on deaths. Flu weakens people who then can die of heart attacks or strokes and Finelli said once that data is included, deaths this season from swine flu may be more than the normal 36,000.

The CDC and WHO both say people who have not been vaccinated should still get an H1N1 vaccine.

The CDC's Dr. James Singleton told the meeting that by February 13, 97 million H1N1 vaccine doses had been given to 86 million people in the United States, or 78 percent of doses shipped.

Singleton said a monthly telephone survey of 6,000 U.S. households suggested that a third of children, many of whom need two doses, and about 20 percent of adults had received swine flu vaccines.

People will need seasonal flu vaccines, too, Cox noted. Globally, H1N1 or untypeable viruses likely to be H1N1 made up about 90 percent of viruses taken from patients but H3N2 flu viruses accounted for nearly 6 percent and are on the rise in China. And a new variant of H3N2 has emerged that is different from the one covered in the current season's vaccine.

Vaccine makers must reformulate the three-ingredient seasonal flu vaccine every year because of such changes.

The United States has contracts with five influenza vaccine makers -- Novartis, AstraZeneca unit MedImmune, Sanofi Aventis, GlaxoSmithKline and Australian vaccine maker CSL.

(Editing by Mohammad Zargham)