Up to 40% in U.S. could get swine flu

ATLANTA — In a new projection, health officials say up to 40 percent of Americans could get swine flu this year and next and several hundred thousand could die without a successful vaccine campaign and other measures.

The estimates by the Centers for Disease Control and Prevention (CDC) are roughly twice the number of those who catch flu in a normal season.

Because the swine-flu virus is new, most people haven't developed an immunity to it. So far, most of those who have died in the United States have had other health problems, such as asthma.

The virus has killed 302 Americans and experts think it has sickened more than 1 million.

Health officials say flu cases may explode in the fall, when schools open and become germ factories, and the new estimates illustrate the need to have vaccines and other measures in place.

The U.S. expects to begin testing on some volunteers in August, with 160 million doses ready in October. Seattle is among the eight U.S. cities in which testing will be done.

The CDC came up with the new projections for the virus' spread last month, but it was first disclosed Friday.

Because so many more people are expected to catch the new flu, formally known as H1N1 influenza, the number of deaths over two years could range from 90,000 to several hundred thousand, the CDC calculated. Again, that is if a new vaccine and other efforts fail.

In a normal flu season, about 36,000 people die from flu and its complications, according to the American Medical Association.

That too is an estimate, because death certificates don't typically list flu as a cause of death. Instead, they attribute a death to pneumonia or other complications.

The World Health Organization says as many as 2 billion people could become infected in the next two years, nearly a third of the world population.

Material from The Seattle Times archive and the Los Angeles Times is included in this report.