Penn Study Pinpoints H3N2 Mutation in Last Year’s Flu Vaccine as Responsible for Lowered Efficacy
Perelman School of Medicine at the University of PennsylvaniaThe below average efficacy of last year’s influenza vaccine (which was only 20 to 30 percent effective) can be attributed to a mutation in the H3N2 strain, a new study reports. With the mutation, most people receiving the egg-grown vaccine did not have immunity against H3N2 viruses that circulated last year.