WASHINGTON - The new swine flu vaccine appears to be highly effective for adults with just one shot, a major boost to the massive immunization campaign that officials are planning to protect against the first influenza pandemic in 41 years, researchers reported Thursday.
Preliminary data from a study involving 240 adults in Australia found that a single standard dose of vaccine produced an immune response within 21 days that appeared easily adequate to protect against the new virus, known as H1N1. The vaccine also appeared safe.
The eagerly awaited findings mark the first results from a flurry of studies that scientists have been rushing to conduct as part of a crash program to develop a vaccine against the virus.
"This is good news," said Anthony Fauci of the National Institute of Allergy and Infectious Diseases, which is leading the nation's efforts to develop the vaccine. "This is very good news. If you needed two doses that would be a major strain on vaccine supplies nationally and globally."
The Health and Human Services Department is planning to release the results of its studies testing the vaccine today. Fauci would disclose no details except to say that the information will be consistent with these findings and show the response occurs even more quickly, after just eight to 10 days.
Results from additional studies will be needed to see whether children need one or two doses, he added. Young children usually need two flu shots because they have never been exposed to the flu.
The National Institutes of Health is conducting a series of studies testing the vaccine on 4,600 volunteers, including adults, children and pregnant women.
Since the virus, known as H1N1, emerged in Mexico, it has spread globally, causing at least 2,837 deaths, including at least 556 in the United States and prompting the World Health Organization to declare the first influenza pandemic since 1968.
The federal government has already spent $2 billion to buy 195 million doses of vaccine and plans to purchase enough to vaccinate every American if necessary. The vaccine campaign would be the most ambitious in U.S. history.
Federal health officials are urging everyone ages 6 months to 24 years to get vaccinated, along with pregnant women, people who care for children younger than age 6, health care workers and adults 25 to 64 with health problems that put them at risk for complications.