Why do you have to get vaccinated with the influenza vaccine (flu vaccine) every year?

You should.: Annual flu shot is recommended for most adults.

Influenza vaccine: Influenza virus changes each year therefore every year new vaccines are made to cover the most likely circulating strains of the virus.

Reality: The flu viruses tend to mutate more often than other viruses.That mutation changes the shell surrounding their insides so the antibodies from past vaccines do not recognize them.(or kill them). In a given year there are at least 4-6 strains circling the globe & air travel increases the spread. Each year they pick the newest strains by frequency to be in the new shot. It's the best plan we have.