An increasing number of influenza experts in the United States are concerned that the wave of the swine flu started to hit the country may peak before a vaccine can do much good, a news story in today's edition of science explains.
On October 15, the US government expects to receive the first batches of a vaccine to thwart the new H1N1 virus causing the pandemic. But this is just as many experts now believe the virus spread can peak in the country. Since it takes about 2 weeks to build immunity after vaccination and there will be a limited quantity for at least a month or more, the vaccine may have little impact in the United States this fall. "This shift in potential timing could significantly diminish the usefulness of vaccination for mitigating the epidemic and could put many at risk of severe disease," predicted the Presidential Council of Advisors on Science and Technology in report of the White House issued August 24
On the good news front, many scientists were afraid that the vaccine against the new H1N1 virus would need two doses to build substantial immunity would mean further delays in the time required to protect the population and twice as many products. But clinical testing of new vaccines against H1N1 published online yesterday by The New England Journal of Medicine show that a single dose can trigger high levels of antibodies in adults. No data are yet available for testing in children, who generally much less robust immune responses to the vaccine against seasonal influenza and require a second dose.
As another document released yesterday, this one in Science Express, once again underlines the widespread use of a vaccine could have a powerful impact against the H1N1 virus, s it arrived early and was widely used. Biostatistician Ira Longini of the University of Washington, Seattle, and colleagues show that the vaccine should be at least 70% of the population, starting with children first, to significantly impede the spread. But Longini, a flu modeler noted, also suspects that the pandemic now spread across the United States as children return to school may peak in mid-October.
Longini and others noted that the pandemic accurately reflects the one that hit the United States in the fall of 1957. If this happens, Longini said in an e-mail notes, "given the plan production and distribution of current vaccines, we will be too late to affect the epidemic. "this is precisely what happened to the vaccine effort in 1957.
with the new pandemic H1N1, the vaccine effort began almost immediately after the virus was isolated in late April. "in May, it seemed that we were in good shape with the vaccine," noted Longini. "There seemed have time. "But now the time seems to be short rapidly.
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