Flu Vaccine Benefit Is “Modest”

Formulation of the seasonal influenza vaccine is a bit of a guessing game, and sometimes antigenic mismatch between vaccine and circulating flu strains is cited to explain suboptimal vaccine performance. But the vaccine used during the 2010–2011 season was well matched to circulating strains: So how did it perform?

Researchers at four large U.S. medical centers ascertained vaccine status among almost 5000 infants, children, and adults who presented with flu-like illness during the 2010–2011 flu season; they used standard polymerase chain reaction techniques to diagnose acute influenza A or B. Overall, about 30% of flu cases occurred in vaccinated people. The overall age-adjusted efficacy of either inactivated or live-attenuated vaccine was e…