The swine flu pandemic has taken a turn in the United States. Doctors in several cities are now reporting fewer cases of the H1N1 virus, prompting some to believe the outbreak may have peaked. Still, the virus has killed nearly 7,000 people worldwide since April, and health officials say there could be another outbreak in the U.S.
At its peak, there were so many outbreaks of H1N1 flu, this children's hospital in Texas had to set up tents for its patients. Two months later, the tents are down and so are the number of people who are sick.
"At some points we were seeing as many as 70 percent of patients testing positive for the flu, and now it's down below 10 percent," Dr. Pat Crocker, Dell Children's Medical Center estimates.
Hospitals in many cities across the United States are seeing the same decline in the number of H1N1 cases.
Flu experts say the cities that were hit hardest with the flu last spring are seeing fewer cases now. There are also a smaller number school closings.
"I believe it's because of herd immunity. The virus spread so widely in the U.S. to a point where 22 million people probably have come into contact with the virus," Dr. Pascal Imperato said.
Officials at the Centers for Disease Control and Prevention say the virus is still widespread, and is behaving in a way they expect.
"So far, no change in the virus," Dr. Anne Schuchat said. "It hasn't become more virulent or changed genetically. We still think the vaccine is a good match with this virus that's circulating."
But scientists in Norway say they have found a mutated form of the H1N1 virus in three of their patients. Two died. The mutation has caused a more severe form of the flu, but health officials don't expect the mutated form to spread.
CDC officials still say that anyone not infected with the H1N1 virus should get the vaccine. They say even though the number of flu cases are declining in U.S. a large number of people are still getting sick in some parts of the country.
"We do not know how long this wave will last, whether there may be multiple waves," Dr. Schuchat said. "We know that flu season can last until May."
And with the holiday season just the around the corner, doctors say there may be another outbreak of the H1N1 flu when people start to travel.