Swine-Flu Vaccines Carry Slight Risk of Rare Disease

Vaccines for the 2009 swine flu virus carry a small increased risk of a rare paralyzing disease, though the benefits of the shots far outweigh their risks, according to a study funded by the U.S. government.

In a survey of about 23 million people in the U.S. who were vaccinated against the H1N1 virus responsible for the first flu pandemic in four decades, there were 77 cases of Guillain-Barre syndrome, or about 1.6 extra cases for every 1 million people vaccinated, researchers led by Daniel Salmon at the U.S. National Vaccine Program Office wrote in the online version of The Lancet medical journal today.