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One Dose Of H1N1 Vaccine May Be Enough

Four and a half months after the new H1N1 swine flu virus was first found infecting people in California and Mexico, researchers are reporting that they've got a vaccine that works better than anyone expected. Researchers say one shot appears to be strong enough to offer protection within 10 days of the shot.

STEVE INSKEEP, host: Here's one less thing to be terrified about - maybe. Researchers are reporting that they've got a swine flu vaccine that works better than anyone expected. NPR's Joanne Silberner reports.

JOANNE SILBERNER: Work on the vaccine began almost as soon as the new H1N1 swine flu virus was discovered last spring. Yesterday, a biotech company headquartered in Australia announced the first results of a vaccine made using conventional vaccine technology. They tried their product on 120 people. Paul Perreault is head of CSL Biotherapies.

Mr. PAUL PERREAULT (President, CSL Biotherapies): What we ended up with was a 97 percent coverage.

SILBERNER: That means 97 percent of the people had an immune response that suggests they could fight off swine flu. CSL also tried the double dose that many people thought would be necessary in another 120 volunteers. The low dose actually worked a bit better - a relief for manufacturers, since the virus that produces the vaccine has been slow to grow in the lab.

And what's especially important to government health officials, the response was seen after just one dose. Now, with most medical treatments, doctors like Kathleen Noozal(ph) want to see lots of studies with big numbers.

Noozal heads a government committee that advises the Department of Health and Human Services. She says in this case that's not necessary because the new swine flu vaccine looks a lot like seasonal flu vaccine - not just the Australian one but four similar ones being tested.

Dr. KATHLEEN NOOZAL: Well, I think it's close to a done deal for healthy adults. Whether children or people with certain chronic diseases that may make it harder for them to respond to vaccines, I think we need to wait and see.

SILBERNER: Those studies are going on now. The flu experts were also really worried about having to give two shots. Added to the seasonal flu vaccine that's now available, that would be three visits to a health facility for vaccination this autumn, and it's hard enough to get people to come even once.

Again, Kathleen Noozal.

Dr. NOOZAL: It's good news for logistics. It's going to be much easier and should save costs to only have to give one dose of vaccine.

SILBERNER: Tony Fauci, head of the National Institute of Allergy and Infectious Diseases, says the new study is exciting and encouraging, and government studies are showing good results as well.

Dr. TONY FAUCI (National Institute of Allergy and Infectious Diseases): We find that a single dose of 15 micrograms of the vaccine, given to adults, induces a robust immune response but does it at an even earlier time point. We get good responses eight to ten days following the single dose of 15 micrograms.

SILBERNER: Earlier than the 21 days in the CSL trial, and important because the vaccine is not expected to be available before mid-October, while the swine flu pandemic is already in high gear in some parts of the country. Fauci suspects that the reason people are responding so well is because the new H1N1 in some way looks like other flu viruses that have been around before, so the body is ready for it.

Trials in another type of vaccine are also going well. In a second report, also in the New England Journal of Medicine, British researchers describe their success with a different type of vaccine, one that contains a chemical that boosts the immune system. But because of the booster, this vaccine will have to go through more extensive human testing before the Food and Drug Administration will approve it.

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