Today's guidelines for K-12 schools will be followed in the weeks ahead by guidelines specific to colleges, day care facilities and employers.
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Government recommendations on swine flu preparations and prevention can also be accessed at www.flu.gov.
Today the first three of thousands of volunteers also begin clinical trials in Seattle so health officials can learn more about whether the immunization shots are safe.
Tests also start Monday at the University of Maryland, Children's Hospital in Cincinnati and Emory University.
The test centers in the United States have been flooded with volunteers to try out the vaccine. The U.S. government alone wants nearly 160 million Americans to be vaccinated, and students are among the first in line. Also on the priority list are pregnant women, people who care for infants under 6 months of age, health care and EMS workers, and anyone under the age of 64 with underlying medical conditions.
Two shots of the swine flu vaccine -- in addition to one shot for the regular seasonal flu -- are expected to be administered to protect people.
"Young adults haven't seen it before," said Dr. William Schaffner, a volunteer in the clinical trials and professor and chairman of the department of preventive medicine at Vanderbilt University School of Medicine in Nashville, Tenn. "You need the first shot to get things going and then the second as a kind of booster that will actually give you complete protection," he added.
The results of this month's clinical trials in the U.S. are expected at the end of September. It could take another four to six weeks from that time to begin a vaccination program, pushing the start of the nation's voluntary vaccination program into November.
That could mean a two-shot series, with shots likely given about three weeks apart, may not bring full immunity against the swine flu virus until December.
"We first recommend that people who are ready and willing to get a seasonal flu vaccine do that quickly," Sebelius said today.
Today health officials also said it would make sense to designate schools as places where vaccinations take place. Duncan said he met yesterday with school boards and teachers associations who are receptive to that plan.
The government's school guidelines released today come in response to extensive school closings last spring when swine flu first surfaced.
In May, the Obama administration urged schools to shut down to stop the spread of swine flu, and hundreds did -- affecting half a million students. But within weeks, the CDC revised its lesson plan.
"In the spring, we had much less information about H1N1 than we have today," said Frieden, who was health commissioner in New York City at the time.
"Once you close a school, as we saw last spring, that causes a very significant ripple effect. We do not want kids going to the mall or anywhere else," Napolitano said. "The whole point is to reduce transmission."
ABC News' Dan Childs contributed to this report.