Centers for Disease Control Estimates 22 Million Cases of H1N1 Flu in US

At least 22 million Americans have come down with the H1N1 swine flu since the virus first surfaced in April and approximately 3,900 people have died, including an estimated 540 children, federal health officials reported Thursday.

While these numbers represent a significant jump in the numbers of sick, hospitalized and dead from previous figures, they don't mean that the swine flu has suddenly gotten worse. Instead, the new numbers are based on extrapolations from laboratory-confirmed cases of swine flu. The earlier numbers were based on laboratory-confirmed cases, Dr. Anne Schuchat, director of the U.S. Centers for Disease Control and Prevention's National Center for Immunization and Respiratory Diseases, said during an afternoon press conference.

H1N1 swine flu has killed more than 4,000 Americans -- perhaps as many as 6,000, the CDC now estimates.

Shockingly, 14 million to 34 million U.S. residents -- the CDC's best guess is 22 million -- came down with H1N1 swine flu by Oct. 17, the six-month anniversary of the beginning of the pandemic. There were about 98,000 hospitalizations (estimates range from 63,000 to 153,000).