About 1 in 5 Americans have been vaccinated against swine flu, according to the government's first detailed estimates of vaccination rates against the new pandemic.

The estimate is based on two government telephone surveys done in December and early January. The surveys concluded that an estimate 61 million people — or about 20 percent of the population — got a shot or nasal spray vaccination against swine flu since the vaccine became available this fall.

One CDC spokesman said the numbers are good, considering it was a hurried campaign against a novel flu virus using a vaccine that did not become available to the general public until early October — and, then, only in limited supplies.

"From our point of view, this looks very successful," said the spokesman, Richard Quartarone.

The report backs up a rough estimate used by health officials in recent weeks that more than 60 million Americans had been vaccinated.

It also shows that vaccination rates were a bit higher for people deemed to be especially vulnerable to the new influenza, including pregnant women, children and people with underlying health conditions

About 28 percent of the 160 million in those targeted groups got vaccine. The report also offered a specific estimate for children — about 29 percent of children ages 6 months through 18 years were vaccinated, CDC officials reported.

Health officials had tried to reserve doses for those groups, especially in the first two months, when vaccine trickled out in short supply.

They were largely successful, according to the new report: Through mid-November, 85 percent of the 21 million doses administered went to people in the target groups.

Supplies improved as the year drew to a close, and more vaccination clinics took all comers. That explains why — as of the end of December — about 74 percent of administered doses had been given to people in the target groups, the CDC said.

The results were released Friday through a CDC publication, Morbidity and Mortality Weekly Report. One survey involved about 6,000 people. The number who responded to the second survey was not included in the report.

Also on Friday, CDC officials released new estimates of the numbers of Americans sickened, hospitalized and killed by the virus.

An estimated 55 million became ill from swine flu from the time it was first identified in April through mid-December — the first eight months of the pandemic. About 246,000 Americans were hospitalized and 11,160 killed.

The CDC last estimated that through mid-November, the pandemic had sickened 50 million Americans and killed 10,000.

The World Health Organization numbers are confirmed, laboratory cases of H1N1; while the CDC number is an educated estimate for the U.S and is acknowledged to be very low.

Swine flu infections have been waning since late October, and no states were reporting widespread cases as of last week.

The Associated Press contributed to this report.

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On the Net:

CDC report: http://www.cdc.gov/h1n1flu