Hmmm
Just so everyone knows, there is such a thing as a flu vaccine. Just because you don’t get your flu shots every year doesn’t mean it doesn’t exist. But to this person’s credit, the flu shot isn’t 100% foolproof. On average, it can save between 40 and 60% of people from falling ill during the flu season.

If you’re wondering why you need a flu shot every one or two seasons, it’s because the vaccine loses its potency over time, unlike the MMR vaccine which can last a lifetime. We’re just thankful that the OP is questioning the existence of a flu vaccine and not the efficacy of vaccines in general.