Dr. Marc Siegel, an associate professor of medicine at New York University School of Medicine in New York City, isn't surprised to hear that a seasonal flu shot offers some protection from the swine flu.
"The implication is that if you trigger an antibody response to an H1N1 flu virus of any kind, it may be useful as part of the body's attempt to fight the flu," he said. "That would explain why it wouldn't immunize you, but could prevent you from having a severe outcome."
Siegel cautioned that the seasonal vaccine the study participants received was last year's vaccine. This year's seasonal vaccine is a different mix of viruses so it may not have any protection against the H1N1 swine flu, he said.
"People who have gotten a seasonal flu shot should not assume they are protected from the H1N1 flu," Siegel said. "Clearly, the amount of protection you are getting from a seasonal flu shot is not nearly of the magnitude that would take the place of getting this year's H1N1 vaccine."
You need both shots, he said.
For more information on flu, visit the Flu.gov.
SOURCES: Jose Luis Valdespino-Gomez, M.D., M.P.H., epidemiologist, Laboratorios de Biologicos y Reactivos de Mexico, Mexico City; Marc Siegel, M.D., associate professor, medicine, New York University School of Medicine, New York City, and author, Swine Flu: The New Pandemic; Oct. 7, 2009, British Medical Journal, online
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