Prevention of Antigenically Drifted Influenza by Inactivated and Live Attenuated Vaccines

Abstract

For many years, placebo-controlled trials of the inactivated influenza vaccine used in the military found that it was 70 to 90% efficacious in preventing infection with influenza as identified by a rise in serum antibody titer, as long as the virus strain used in the vaccine resembled the strain in circulation.1 Questions have been raised as to how well the vaccine provides protection against infection when the circulating virus has antigenically drifted and differs to some extent from the strain used in the vaccine.2 The validity of using serologic confirmation of infection, rather than isolation and identification of the virus, . . .