Scientists investigating why an unusually high number of middle-aged individuals contracted H1N1 influenza last year are blaming the increase on a newly discovered mutation in the virus.
“We identified a mutation in recent H1N1 strains that allows viruses to avoid immune responses that are present in a large number of middle-aged adults,” Scott Hensley, an assistant professor at Wistar’s Cancer Center and a member of Wistar’s Vaccine Center, said.
Researchers from Wistar Institute discovered 41 percent of people born from 1965 to 1979 have this antibody response.
Wistar researchers further determined that the antibodies produced for determining which influenza strain to focus on each year may not be as similar to immunity as originally thought.
“...We may need to re-evaluate how we, as a community, detect antigenically distinct influenza strains and how we choose vaccine strains," Hensley said.
Influenza causes 36,000 deaths in America and approximately 500,000 deaths worldwide each year.
"Our immune systems are imprinted the first time that we are exposed to influenza virus," Hensley said. "Our data suggest that previous influenza exposures that took place in the 1970s and 1980s influence how middle-aged people respond to the current H1N1 vaccine."