To everything there is a season, and for the flu, it’s wintertime. Flu cases peak between December and February, and the flu vaccine is your best defense. Getting the vaccine means you will be less sick even if you get a breakthrough infection.
However, your immune system is in a constant race against the flu virus. Like the virus that causes COVID-19, influenza rapidly changes and mutates into new variants, so manufacturers have to update the flu shot to try to keep pace. After identifying a new flu variant, it takes manufacturers about six months to update the vaccine – and in the meantime the virus can mutate again. This phenomenon is called antigenic drift, and can reduce the effectiveness of the flu vaccine for that season.
