WASHINGTON — Good news in the world’s flu fight: One dose of the new swine flu vaccine looks strong enough to protect adults — and can spark protection within 10 days of the shot, Australian and U.S. researchers said Thursday.
Australian shot maker CSL published results of a study that 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. That’s remarkable considering scientists thought it would take two doses.
U.S. data to be released today confirm those findings, and show the protection starts rapidly, Dr. Anthony Fauci of the National Institutes of Health told The Associated Press.
“This is quite good news,” Fauci said.
The dose question has an important ramification: It means people will have to line up for influenza vaccinations twice this year instead of three times — once for the regular winter flu shot and a second time to be inoculated against swine flu, what doctors call the 2009 H1N1 strain.
Thursday’s swine flu vaccine reports center on adults; studies in children aren’t finished yet.
But scientists had feared 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.
Chinese manufacturers gave the first hint a week ago that one dose could be enough. But different manufacturers make different formulations of the vaccine, so more evidence was needed.
Thus the CSL study, rushed out by the New England Journal of Medicine late Thursday, is welcome news. In a 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.
“It’s really striking how incredibly similar this is to every other study of a seasonal flu vaccine I’ve ever seen,” said Dr. John Treanor, a flu specialist at the University of Rochester who examined the data.
CSL, which is one U.S. vaccine supplier, found the same side effects in its study that people experience with regular flu vaccine, which is no surprise since this shot is merely a recipe change from the annual standby. About 45 percent of recipients had mild reactions such as a headache, sore arm or redness at the shot site.
Today, the NIH is set to release results of its own studies of hundreds of adults that confirm that one shot works, Fauci said. Plus, the U.S. work shows that people are protected between eight days and 10 days after that inoculation, he said.
One dose means tight supplies of H1N1 vaccine won’t be stretched so badly after all. 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.
The winter flu vaccine is widely available now, and U.S. health authorities urged people Thursday to get it out of the way now before swine flu shots start arriving in mid-October.
Despite all the headlines about swine flu, which has become the main influenza strain circulating in the world, doctors do expect some garden-variety flu.
to hit this fall too — the kind that every year kills 36,000 Americans and hospitalizes 200,000.
