Swine flu to hit 50% of us?

Swine flu to hit 50% of us?

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...

By Rob Stein

The Washington Post

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H1N1 virusscenarios
90,000

Maximum projected deaths in United States

1.8 million

Number who could end up in a hospital

120 million

Number of Americans who could show symptoms

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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, clinically called H1N1, could cause symptoms in 60 million to 120 million people, more than half of whom might seek medical attention, and could peak before a vaccine is widely available, the President's Council of Advisors on Science and Technology estimated in an 86-page report assessing the government's response to the first influenza pandemic in 41 years.

Although most 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.

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 last spring and during the Southern Hemisphere's winter, 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, noting the estimates are based on various assumptions, including that the virus will not mutate into a more dangerous form or infect more older people.

"If it turned out to affect a lot more adults," Lipsitch said, "the severity would be a lot worse."

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.

Lipsitch stressed that the outbreak could turn out to be milder, too. The primary purpose of the estimates was to help guide planning to protect the public. For example, it was estimated that the outbreak could peak in mid-October, so the panel urged expediting a vaccine.

In addition, the panel recommended clarifying how antiviral drugs should be used to fight the pandemic. The swine-flu virus emerged last spring in Mexico and quickly spread to the United States and around the world. Although far less dangerous than initially feared, the virus has sickened children and young adults more frequently than the typical seasonal flu.

"This isn't the flu that we're used to," Health and Human Services Secretary Kathleen Sebelius said. "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 pandemic has caused significant disruptions and economic damage in parts of the Southern Hemisphere, and has contributed to 1,799 deaths in at least 168 countries, including at least 522 in the United States. A second wave of infection is expected to begin within weeks in the Northern Hemisphere as schools reopen and cooler temperatures return.

Overall, the panel praised the federal government's response, which has included signing contracts to spend nearly $2 billion to buy at least 159 million doses of vaccine from five companies rushing to produce it. But the first batch is not expected until mid-October, when the outbreak could peak.

The report recommends that some vaccine be made available by mid-September for those at highest risk by asking manufacturers to start filling vials with vaccine even though studies to determine dosages and whether a booster is necessary aren't complete.