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...