By Tom Randall Nov. 12 (Bloomberg) — Seasonal flu shots didn’t protect against the new swine flu strain that’s now responsible for 99.6 percent of U.S. infections, according to a federal study. Patients who were vaccinated in the 2008-2009 flu season were just as likely as unvaccinated people to become infected during the first wave of the swine flu pandemic, according to today’s study by the U.S. Centers for Disease Control and Prevention in Atlanta. The study supports findings from a similar analysis in Australia, where scientists found no evidence of any effect from the seasonal vaccine on swine flu. Swine flu, or H1N1, infected as many as 5.7 million Americans from April through July, according to the CDC. The outbreak is at its highest level now and is responsible for almost 8 percent of U.S. doctor visits, the agency said. “These results, taken together with other studies, do not support an effect of seasonal 2008-2009” vaccine on swine flu, CDC scientists said in an editorial following the study in the agency’s Morbidity and Mortality Weekly Report . “Results from additional studies using more rigorous study designs and methods currently under way in the U.S. and other countries will further define seasonal influenza vaccine effectiveness.” Previous studies from Mexico and Canada showed conflicting results, with the Mexico study showing a protective effect from the seasonal vaccine and a cluster of five Canadian studies showing that the seasonal vaccine actually increased chances of contracting swine flu. The report from Mexico may have been skewed by the people chosen for the study, and the Canadian studies haven’t been published yet, according to the CDC. The CDC study compared vaccination rates of 356 people who contracted swine flu with rates among people who stayed healthy, finding no significant difference. It also supports studies that showed levels of swine flu protective antibody in the blood aren’t affected by the seasonal flu vaccine. To contact the reporters on this story: Tom Randall in New York at trandall6@bloomberg.net
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Seasonal Flu Shots Don’t Protect Against Swine Flu Strain, U.S. Study Says
