Main Flu Strain Has Mutated; Current Flu Vaccines May Not Prevent Infection
It's bad news for the vaccine, said Scott Hensley, a professor of microbiology at the University of Pennsylvania who led the study. Flu vaccines protect against four strains: H3N2, H1N1 and two strains of influenza B. The study covers just H3N2, but that happens to be the main circulating strain.