In an effort to assuage growing concerns about the swine flu pandemic, the U.S. Department of Health and Human Services (HHS) pulled out all stops today to broadcast the news that one dose of a vaccine against the novel H1N1 virus will likely will protect adults.
As HHS Secretary Kathleen Sebelius explained at a press conference this afternoon, the preliminary findings from clinical studies that one dose triggers a strong antibody response in adults “is critically important news.” Flanked by top officials from the National Institutes of Health, the Centers for Disease Control and Prevention, and the Food and Drug Administration, Sebelius noted that if two doses were necessary, as some had predicted, it would take longer to immunize the population and require more product. But she also emphasized that no data yet exist about how the vaccine works in children and pregnant women, two groups that remain at high risk for developing severe disease from the virus. And the timing of the vaccine's arrival remains a major concern, she said.
Anthony Fauci, head of the NIH’s National Institute of Allergy and Infectious Diseases, described early data from adult trials sponsored by his institute. In people ages 18 to 64 who received one of two different pandemic H1N1 vaccines, 80% to 96% developed a “robust immune response” 8 to 10 days after a single 15 microgram dose. People 65 and older did not respond as well, with only 56% to 60% reaching similar antibody levels. The new data mesh with data reported yesterday in The New England Journal of Medicine of trials conducted outside the United States.
The unusual high-level press conference to discuss preliminary results from clinical studies reflects the high level of anxiety in the country about the pandemic. The new information, Sebelius said, “shortens the window of worry, and more people can be protected much earlier.” It also means that the limited supply of vaccine, which will not start to arrive in the United States until mid-October, can be made available to more people in other countries more quickly.
Still, many experts say it appears that the pandemic may well peak in the United States in mid-October, before the vaccine arrives. “The models are based on assumptions,” said Fauci. “Certainly there could clearly be peaks before people get vaccinated, but there are other ways to mitigate the spread.” Anne Schuchat, head of the CDC’s National Center for Immunization and Respiratory Diseases, stressed that the virus pops up in different communities at different times. “We do believe that many prevention opportunities will be possible with vaccine, particularly now that we have this great news that protection might be possible in adults after that first dose,” said Schuchat.