U.S. officials said Monday that it's too early to say the swine-flu threat is receding, even though there are some signs the outbreak may not be as serious as originally feared.
Homeland Security Secretary Janet Napolitano said the outbreak could die down with warmer weather only to roar back during fall flu season. And she said the public shouldn't be alarmed if the World Health Organization declares that the new virus has officially begun a pandemic, meaning it has spread pretty much globally.
That word describes "geography, not severity" and thus wouldn't change U.S. steps to stem infections that have been confirmed in more than 380 people in more than half the states, she said.
Another top U.S. health official said "there are encouraging signs" of a leveling off in the severity of the threat, but added that it's still too early to declare the problem under control.
"I'm not ready to say that yet," Dr. Richard Besser, acting director of the Centers for Disease Control and Prevention, said when asked about indications by Mexican health authorities that the disease has peaked there.
"What we're seeing is an illness that looks very much like seasonal flu. But we're not seeing the type of severe disease that we were worrying about," Besser told network television interviewers. He noted that roughly 36,000 people die each year in this country from the winter flu, so it's still a serious matter.
About 300 cases of swine-flu virus have been confirmed in 36 states so far, according to a count by The Associated Press.
"We are by no means out of the woods," Besser said. "In previous pandemics, there have been waves and you don't know what this virus is going to do."
U.S. confirmed cases from CDC or states: New York, 90; Texas, 43; California, 29; Delaware, 20; Arizona, 18; South Carolina, 15; Illinois, nine; Colorado, Louisiana, Massachusetts and New Jersey, seven; Florida, five; Alabama and Maryland, four; Indiana, Ohio, Oregon, Virginia and Wisconsin, three; Connecticut, Kansas and Michigan, two; and one each in Nebraska, Iowa, Kentucky, Minnesota, Missouri, Nevada, New Hampshire, New Mexico, North Carolina, Pennsylvania, Rhode Island, Tennessee, Idaho and Utah.
There has been one death in the United States, a toddler who succumbed to the disease after he was brought to this country from Mexico.
Besser said health authorities also are concerned about indications that the flu had so far struck the young more heavily than older people, and that there still may be deaths from it.
He also said he didn't think it was necessarily time to ease off on school closings and other steps that have been taken to contain the spread of the infection.
"We're seeing infections in almost every state," Besser said, "and as that occurs, those who have underlying problems (such as the elderly and people with compromised immune systems) may be affected more. ... It may be that this disease is starting first in children, and then moving to the elderly, so there's still much that we do not know."
Besser said that as a parent and a pediatrician, he thinks it's best for kids to be in school, whenever possible, and that adjustments in school shutdowns might be possible "as we learn and see that this virus is not more serious than ordinary flu."
Asked whether the food supply has been compromised, he said, "It may be that pigs have more to fear from people than people have to fear from pigs."
"With each day some of the uncertainty goes away, we learn more, and we're seeing encouraging signs," Besser said. "The encouraging signs have to do with severity." He summed up the situation by saying he was "precautiously optimistic" about trends now surfacing.
But he hastened to add that people still need to take everyday precautions, like vigorous and frequent hand washing, covering their noses and mouths when they sneeze and staying home when they're sick.
Besser said that what now ensues in the Southern Hemisphere, which is just entering flu season, will be "critically important for us to understand as we think about the decisions around vaccination."
The CDC chief was interviewed on CBS's "The Early Show" and NBC's "Today" show.