It seems one shot, instead of two, may protect from swine flu. But you also need your usual seasonal flu shot.

RODALE NEWS, EMMAUS, PA—One dose of the H1N1, or swine flu, vaccine could be potent enough to provide adults with protection against the virus that is now circulating in schools and universities around the country. Previously, many researchers and doctors believed two doses of the vaccine would be necessary to provide sufficient protection. But two new studies out of Britain and Australia, and just published online in the New England Journal of Medicine, found that adults mounted a strong enough immune response to offer full protection within two weeks of getting the shot. Friday, the National Institutes of Health announced they were finding similar results in the preliminary round of clinical trials.

THE DETAILS: In the NIH trials, early data mimic results out of Britain and Australia. In eight to 10 days after swine flu vaccination, researchers noted a "robust immune response" in 96 percent of adults 18 to 64 years old, and in 56 percent of those 65 and older who received a single 15-microgram vaccine. Trials including children and pregnant woman are being studied now, and results are expected within the next few weeks. Also of note, the U.S. Centers for Disease Control and Prevention (CDC) announced recommendations dealing with who should get the swine flu antiviral drugs. High-priority patients for antiviral medications include people hospitalized with suspected or confirmed influenza, and people with suspected or confirmed flu who are at higher risk for complications.