Had flu? You may have H1N1 protection

Mon Nov 16, 2009 6:15pm EST
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By Maggie Fox, Health and Science Editor

WASHINGTON (Reuters) - People who have had repeated flu infections -- or repeated flu vaccines -- may have some protection against the new pandemic swine influenza, U.S. researchers said on Monday.

They found evidence that the human immune system can recognize bits of the new H1N1 virus that are similar to older, distantly related H1N1 strains.

"What we have found is that the swine flu has similarities to the seasonal flu, which appear to provide some level of pre-existing immunity. This suggests that it could make the disease less severe in the general population than originally feared," said Alessandro Sette, director of the Center for Infectious Disease at California's La Jolla Institute.

The study, published in the Proceedings of the National Academy of Sciences, may also help explain why many older people are less likely to have severe disease, said Allison Deckhut-Augustine of the National Institute of Allergy and Infectious Diseases.

"Adults may have some pre-existing immunity for H1N1," Deckhut-Augustine said in a telephone interview.

That does not mean older people are protected from infection, and Deckhut-Augustine stressed that people should still be vaccinated against H1N1.

Swine flu has infected millions of people globally and killed an estimated 3,900 in the United States alone, according to the U.S. Centers for Disease Control and Prevention. Drug makers are struggling to make vaccines and governments are working to vaccinate their populations.

Bjoern Peters and colleagues at the La Jolla Institute looked at flu epitopes -- molecular markers or structures that the immune system recognizes -- dating back 20 years.   Continued...

<p>Three-year-old Charles Clarke Jr. gets an H1N1 swine flu vaccine injection in his leg at an Asthma fair at Children's Hospital in Boston, Massachusetts November 14, 2009. REUTERS/Brian Snyder</p>