There is evidence indicating that getting flu shots year after year could actually lower your immune system’s effectiveness. Recently, Dr. Edward Belongia of Wisconsin’s Marshfield Clinic Research Foundation discussed findings that children who had been vaccinated annually over a number of years were more likely to contract the flu than kids who were only vaccinated in the season in which they were studied.
Belongia, an epidemiologist, stated in a recent interview [2]:
The vaccine was significantly more effective … if they had not been vaccinated in the previous five years.