Originally Posted by
threeighteen
In fact, it's so well proven that you have to get it every year, and even if you do get it, you still have a good chance of getting the flu.
That may because unlike COVID where they are vaccinating against a known virus, vaccine makers have to guess what will be the dominant strain of flu every year. As to yearly updates that’s because the flu mutates significantly all the time. Finally people who get the flu shot rarely end up in the hospital with severe flu.