WASHINGTON — Nearly 300 schools scattered around the country closed as the nation's swine flu caseload rose to 130 yesterday, and U.S. authorities said they eventually could produce enough vaccine for everyone if necessary — but that shots couldn't begin until fall at the earliest.

The outbreak penetrated more than a dozen states and even touched the White House, which disclosed that an aide to Energy Secretary Steven Chu apparently got sick helping arrange President Obama's recent trip to Mexico but that the aide did not fly on Air Force One and never posed a risk to the president.

The CDC confirmed 109 cases yesterday, and state officials confirm 21 more. Cases now are confirmed in: New York, Texas, California, South Carolina, Kansas, Massachusetts, Indiana, Ohio, Arizona, Michigan, Nevada, New Jersey, Delaware, Colorado, Georgia, Minnesota and Virginia.

An estimated 12,000 people logged on to a webcast where the government's top emergency officials sought to cut confusion by answering questions straight from the public: Can a factory worker handling parts from Mexico catch the virus? No. Can pets get it? No.

And is washing hands or using those alcohol-based hand gels best? Washing well enough is the real issue, answered Dr. Richard Besser, acting chief of the Centers for Disease Control and Prevention. He keeps hand gel in his pocket for between-washings but also suggested that people sing "Happy Birthday" as they wash their hands to make sure they've washed long enough to get rid of germs.

It is safe to fly, U.S. officials found themselves stressing after Vice President Joe Biden got off message yesterday. Biden said he'd discourage family members from flying or even taking the subway. The White House insisted the vice president meant to say he was discouraging just nonessential travel to Mexico, the hardest-hit area.

"It is safe to fly. There is no reason to cancel flights," Transportation Secretary Ray LaHood said. Not just planes but "all modes of transportation are safe in America," he added.

But anyone with flu-like symptoms shouldn't be traveling anywhere unless they need to seek medical care — the same advice that doctors give during the winter when regular flu kills 36,000 Americans each year.

"If you're ill, you shouldn't get on an airplane or any public transport to travel," CDC's Dr. Anne Schuchat told a congressional hearing. "If you're sick, stay home. I can't tell you how many times I've said that this week."

FAIRLY MILD CASES

So far, U.S. cases are fairly mild for the most part, with one death, a Mexican toddler who visited Texas with his family — unlike in Mexico where more than 160 suspected deaths have been reported. In fact, Schuchat said most of the U.S. cases so far didn't need a doctor's care.

The WHO also said it will stop using the term "swine flu" to avoid confusion over the danger posed by pigs. It will instead refer to the virus by its scientific name, "H1N1 influenza A."

The Health and Human Services Department said yesterday the government was buying 13 million treatment courses of anti-flu drugs to replenish the U.S. strategic stockpile and help fight the flu outbreak. The U.S. yesterday also began sending 400,000 treatment courses of the drugs to Mexico to help against swine flu there.

HHS Secretary Kathleen Sebelius said the government was spending an estimated $251 million to replace the 11 million treatment courses offered to states recently and to purchase 2 million more courses. Part of the additional 2 million treatment courses will replace the drugs sent to Mexico.

Along with the cases in the U.S. and Mexico, confirmed cases elsewhere include: 34 in Canada, 13 in Spain, eight in Britain, three in Germany and in New Zealand, two in Israel and one each in Switzerland, Austria and the Netherlands.

The Red Cross said it was readying an army of 60 million volunteers who can be deployed around the world to help slow the virus' spread.

SPORTS SUSPENDED

The number of closed schools in the U.S. more than doubled overnight to nearly 300 when the Fort Worth Independent School District in Texas announced it was closing its 140 schools, affecting about 80,000 students. High schools sports were suspended in Texas and Alabama.

"We do think it's very prudent to close schools when a case has been confirmed or is highly suspect," CDC's Schuchat told lawmakers yesterday.

Colleges are seeing cases, too. Four were confirmed at the University of Delaware, and in Pennsylvania, Slippery Rock University will hold a separate graduation tomorrow for 22 students who recently returned from Mexico and won't be beyond an incubation period.

"People went to Mexico for spring break, came back and now we're seeing second and third generation spread," said Dr. Dan Jernigan, CDC senior science officer.

MEXICO OPTIMISTIC

Mexico's top medical officer, meanwhile, voiced optimism yesterday that swine flu has slowed in the nation hardest hit by the virus, but the WHO cautioned there is no evidence the worst of the global outbreak is over.

Mexican Health Secretary Jose Angel Cordova said new cases have leveled off and the death rate has been nearly flat for several days. He said the next few days would be critical in determining whether the virus was truly on the decline.

"The fact that we have a stabilization in the daily numbers, even a drop, makes us optimistic," he said. "Because what we'd expect is geometric or exponential growth. And that hasn't been the situation. So we think we're on the right track."

The health ministry, which earlier said 168 people were believed killed by swine flu in Mexico, yesterday would only confirm 12 deaths and would not say how many were suspected.

Mexico has imposed what amounts to a five-day shutdown of the country, beginning today, in hopes of slowing the virus. All but the most essential government services will be suspended, most businesses have been urged to close, and Mexicans have been encouraged to stay in their homes.