President Obama said today that while the United States is still preparing for the worst in the wake of the swine flu scare, the outbreak could end up falling short of a pandemic and run its course just "like ordinary flus" that pass through the country every winter.
"I'm optimistic that we're going to be able to manage this effectively," Obama said.
"We don't know for certain that this will end up being more severe than other flus," he said. "It may turn out that H1N1 runs its course like ordinary flus."
The head of the CDC's influenza division, Dr. Nancy Cox, said today that preliminary research suggests the makeup of this current virus is lacking some key components of the 1918 flu pandemic that killed between 30 million and 50 million people and to which the new strain has recently been compared.
"What we have found by looking very carefully at the sequence of the new H1N1 virus is that we're not seeing the markers for virulence that we saw in the 1918 virus," she said. But she added that scientists still may not know all they need to know about the 1918 H1N1 strain and are "continuing to look for virulence markers."
Dr. Julie Gerberding, former head of the CDC, said on ABC's "Good Morning America" that we "have to be careful not to over-rely on that kind of information because these flu viruses always evolve."
Officials still remain cautious about the outbreak. Friday afternoon a United Airlines flight from Germany to Washington, D.C., was diverted to Boston after a passenger complained of flu-like symptoms.
Meanwhile, as more schools across the United States close in response to the swine flu outbreak, some estimate that more than a quarter of a million schoolchildren were out of school this morning.
In Brownsville, Texas, officials ordered the closing of the entire school district today, a move taken in several school districts around the country, including nearby Fort Worth.
But Dr. Richard Besser, acting director of the Centers for Disease Control and Prevention, told "GMA" they still believe schools should only be closed if they have a confirmed case of the flu.
"Our recommendation right now is you have a case in the school, you dismiss the students until you've been able to sort out the situation and ensure there is not ongoing transmission."
The school closures have turned the lives of thousands of families upside down as they struggle to arrange child care and work schedules.
But Besser said the final decision should still be made locally, in accordance with the communities' "comfort level."
In the U.S., the CDC reports a total of 144 cases in 21 states and one confirmed death, with more flu cases likely to come as state and federal health officials analyze samples.
The latest state to join the list of state-confirmed cases as of this afternoon is Florida, where Gov. Charlie Crist announced two cases of swine flu -- an 11-year-old boy and a 17-year-old girl.
South Korea and Germany became the latest countries to report confirmed cases of swine flu Friday. A total of 12 countries now have at least one case, and the number of confirmed cases is 331, according to the World Health Organization, up from 257 Thursday.
U.S. authorities have promised to produce enough swine flu vaccine for the country, but it won't be available until fall at the earliest.