One Dose Of Swine Flu Vaccine Effective For Adults
Posted on: Friday, 11 September 2009, 12:45 CDT
Australian and U.S. researchers said Thursday that one dose of the new swine flu vaccine looks strong enough to protect adults - and can spark protection within 10 days of the shot, The Associated Press reported.
Results of a study conducted by Australian vaccine maker CSL Ltd. found between 75 percent and 96 percent of vaccinated people should be protected with one dose - the same degree of effectiveness as the regular winter flu shot.
Scientists originally thought it would take two doses to protect most people.
Dr. Anthony Fauci of the National Institutes of Health told The Associated Press that U.S. data to be released Friday confirmed those findings and show that protection starts rapidly.
Therefore, people will only have to receive two influenza vaccinations this year instead of three -- one for the regular winter flu shot and a second to be inoculated against swine flu, or the 2009 H1N1 flu strain.
However, the new swine flu vaccine reports center on adults, as studies in children aren't yet completed.
Experts originally believed that people of all ages would need two shots about a month apart because the new H1N1 strain is so genetically different from normally circulating flu strains that most of the population has little if any immunity.
In the CSL study of 240 adults, half younger than 50 and half over, one shot prompted the same kind of immune response indicating protection that is seen with regular flu vaccine. And a standard 15-microgram dose - not the double dose that also was tested - was enough, according to the report published in the New England Journal of Medicine late Thursday.
Dr. John Treanor, a flu specialist at the University of Rochester who examined the data, said it was really striking how incredibly similar the data is to every other study of a seasonal flu vaccine she had ever seen.
Fauci said the NIH is set to release results of its own studies on Friday involving hundreds of adults confirming that one shot works. He said the U.S. work also shows that people are protected between 8-10 days after that inoculation.
The U.S. has ordered 195 million doses, based on the hope that 15 micrograms was indeed the right dose. Had it taken twice that dose, or two shots apiece, half as many people could have received the vaccine.
Now that the winter flu vaccine is widely available, U.S. health authorities urged people Thursday to get it out of the way now before swine flu shots start arriving in mid-October.
Even though swine flu has become the main influenza strain circulating in the world, doctors do expect some garden-variety flu, which every year kills 36,000 Americans and hospitalizes 200,000, to hit this fall as well.
Health and Human Services Secretary Kathleen Sebelius, who scheduled her own seasonal shot for Friday, advised Americans to take some individual responsibility to stay healthy during the flu season.
Dr. Nancy Nielsen, past president of the American Medical Association, said waiting to get the first inoculation out of the way is not in anybody's best interest. She advised that doctors must have completed regular vaccinations by the time H1N1 shots are due.
Meanwhile, experts have warned that there’s no way to predict how much of either flu strain will circulate.
Dr. Thomas Frieden, director of the Centers for Disease Control and Prevention, warned that we are in uncharted territory this year.
“Some parts of the Southeast in the past few weeks have experienced as much flu as is usually seen in the middle of winter. So far, it's all the H1N1 variety, with schools and colleges experiencing outbreaks almost as soon as classes began,” he said.
A stark new estimate published Thursday in the journal Science suggests a typical school student who catches swine flu will spread it to two to three classmates.
That estimate was based on how swine flu spread through a New York City school in April, and some other schools, said flu specialist Ira Longini of the University of Washington in Seattle.
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Source: RedOrbit Staff & Wire Reports
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