Swine flu was widespread in only 25 states last week - mostly in the Northeast and Southwest, officials at the Centers for Disease Control and Prevention said Friday.
In late October, 48 states were reporting widespread cases of swine flu. But since then, there's been a decline across the country, and it appears that a fall wave of swine flu infections has peaked.
Meanwhile, a shortage of swine flu vaccine is easing, with 73 million doses now available, roughly twice as much as there was a month ago. And another 10 million doses are expected in the next week, said Dr. Thomas Frieden, the CDC's director.
Initially, limited supplies caused the CDC to advise state and local health officials to reserve doses for those at highest risk for severe complications from swine flu or those who take care of them. That group includes pregnant women, children and young adults, health-care workers and people with asthma and certain other health problems.
Demand for the vaccine is still high in many places, but enough has become available that some communities are now giving it to people outside the priority groups, Frieden said.
"The number of communities that do that will increase in the coming weeks," he predicted, at a press conference in Atlanta.
At least three states - Alaska, Arkansas and Oklahoma - have begun offering swine flu vaccine to all comers. And some communities have opened vaccinations up, including Broward County, Fla., and Sacramento County, Calif., said Paula Steib, spokeswoman for the Association of State and Territorial Health Officials.
Since it was first identified in April, swine flu has sickened an estimated 22 million Americans and killed 4,000. It has proved to be similar to seasonal flu but a bigger threat to children and young adults.
The swine flu pandemic has so far hit in two waves in the United States: First in the spring, then a larger wave that started in the late summer.
Flu is hard to predict, and health officials say they are worried of the possibility of a third wave this winter. The CDC said a new round of public service announcements about getting vaccinated are to begin next week.