Government health officials say swine flu has sickened about 22 million Americans since April.

They say about 4,000 have died, including 540 children.

The startling new figures -- about four times higher than previous death estimates -- don't mean swine flu has suddenly gotten worse. Instead, the Centers for Disease Control and Prevention on Thursday called them a long-awaited better attempt to understand the virus' true toll.

The CDC now believes that about 98,000 people have been hospitalized in the first six months of the nation's swine flu epidemic, including 36,000 children.