Single shot of vaccine may be all adults need

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. The findings indicate that plans to vaccinate millions of Americans – the most ambitious vaccine campaign in U.S. history – and around the world could occur much more quickly and require far less vaccine than officials had feared when they assumed two doses would be necessary.

“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 findings will be consistent with these findings and show the response occurs even more quickly, after just eight to 10 days.

“The NIH clinical trials results verify and corroborate the exciting results” from the Australian study, Fauci said, adding there was no reason to suspect vaccine produced by any of the five companies producing the vaccine would be different.

“They are really the same. The seed virus is the same. They are made the same way,” Fauci said. “Even though they are from different companies you don’t usually see differences from one company to another.”

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 a total of 4,600 volunteers, including adults, children and pregnant women.

“We will hopefully get some information about kids from our trial in a couple of weeks,” Fauci said.

The results from the CSL vaccine manufacturer in Australia will be published in the New England Journal of Medicine but were released early by the journal online Thursday because of the urgency of the findings. The study involved a standard dose of 15 micrograms of vaccine.

They were published with a second study led by Iain Stephenon of the Leicester Royal Infirmary in Britain involving 175 healthy British adults ages 18 to 50 who received another version of the vaccine made by Novartis. They received half that dose along with a substance known as an adjuvant, which can boost the vaccine’s effectiveness. The study found that produced adequate immune response within 14 days. Adjuvants have been used widely in Europe, which could extend the supplies even further.

U.S. officials were considering approving an adjuvant in this country if supplies ran low.

Since the virus, known as H1N1, emerged last spring in Mexico the virus has spread around the world, 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.

Because the virus is new, most people have no immunity against it, raising concerns that it could cause widespread illness and death. A presidential advisory council recently estimated the virus could infect half of all Americans, leading to 1.8 million hospitalizations, including at least 300,000 who would require intensive care, and as many as 90,000 deaths. About 36,000 Americans die each year from the seasonal flu.

The virus continued to spread throughout the summer, causing outbreaks at summer camps and elsewhere, but officials are expecting a second larger wave of cases beginning this fall and winter as children and college students return to class and colder temperatures return. Increased cases are already being reported in some parts of the United States, particularly the Southeast.

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.

The results came as top U.S. health officials urged Americans to get vaccinated against the seasonal flu, which they warned could also still pose a danger, especially to the elderly.