Flu Vaccine Impeded by Mutation Last Year, May Underperform This Year, Too

Last year’s influenza vaccine has egg on its face, having demonstrated only 20% to 30% effectiveness—a low level of performance attributed to an adaptive mutation that affected egg-grown vaccines, but not vaccines that were produced in non-egg systems. The adaptive mutation, which was uncovered by scientists based at the University of Pennsylvania School of Medicine, affects a hemagglutinin (HA) protein that occurs in H3N2 viruses.Due to the mutation, most people receiving the egg-gr