August 25, 2009 in Nation/World

Swine flu could infect half of U.S.

President’s council says pandemic will strain nation’s health system
Rob Stein Washington Post

Vaccine slow to take effect

It will likely be Thanksgiving before a significant number of Americans who get the swine flu vaccine are protected, health officials said Monday.

Roughly 50 million doses of vaccine are expected to be available by mid-October. But for those who get initial doses right away, that will only mark the beginning of a vaccination process that will take five or more weeks.

Here’s why: Health officials believe most people will need two shots, spaced three weeks apart, and it will take a week or two after the second dose before immunity kicks in. That’s five or six weeks in all.

Associated Press

Swine flu could infect half the U.S. population this fall and winter, hospitalizing up to 1.8 million people and causing as many as 90,000 deaths – more than double the number that occur in an average flu season, according to an estimate from a presidential panel released Monday.

The virus could cause symptoms in 60 million to 120 million people, more than half of whom might seek medical attention, the President’s Council of Advisors on Science and Technology estimated in an 86-page report to the White House assessing the government’s response to the first influenza pandemic in 41 years.

Although most of the cases probably would be mild, up to 300,000 people could require intensive care, which could tie up all those beds in some parts of the country at the peak of the outbreak, the council said.

“This is going to be fairly serious,” said Harold Varmus of Memorial Sloan-Kettering Cancer Center in New York, co-chairman of the 21-member council. “It’s going to stress every aspect of our health system.”

The estimates mark the first time experts have released specific calculations about the possible impact of the pandemic in the United States.

The “plausible scenario” is based on previous pandemics, especially the 1957-’58 Asian flu, and how the swine flu behaved in the United States this spring and during the Southern Hemisphere’s winter over the past few months, said Mark Lipsitch of the Harvard School of Public Health, who helped prepare the estimate.

“They are not a prediction, but they are a possibility,” he said in a telephone interview, noting that the estimates are based on various assumptions, including that the virus will not mutate into a more dangerous form or infect more older people.

While the seasonal flu causes about 36,000 deaths and 200,000 hospitalizations each year, the lack of immunity to the swine flu virus probably will lead to many more people becoming infected and possibly dying – as many as 90,000, the council said. And while most deaths during a typical flu season occur in the elderly, swine flu is more likely to kill children and young adults, the panel said.

“This isn’t the flu that we’re used to,” said Health and Human Services Secretary Kathleen Sebelius. “The 2009 H1N1 virus will cause a more serious threat this fall. We won’t know until we’re in the middle of the flu season how serious the threat is, but because it’s a new strain, it’s likely to infect more people than usual.”

The report recommends that a portion of the vaccine be made available by mid-September for those at highest risk by asking the manufacturers to start filling vials with vaccine even though the studies to determine dosages and whether a booster will be necessary have not been completed.

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