From what I understand, random interactions with wild pathogens can prime the immune system in the wrong way, leading it down the wrong path. This is why some people can get lucky with immunity and be super resistant to flu, because they happened to luck into a response that targets a common factor in most flu strains. Other people have bad luck and target some area that mutates frequently, and they proceed to get walloped by every flu strain, every year.
This is why it's hard to make a 'super vaccine' for flu, becuase it takes many rounds of shots to retrain some people's immune systems once they've latched on to the wrong recipe for antibodies.
And every time you generate an immune response you are honing your natural receptors so although they are more specific to the specific virus at hand, they lose general response, so this can backfire for example if you over-vaccinate with the wrong strain of flu and this one year the flu changes direction, mutationally.
Wait, so what are we supposed to do. If you over vaccinate is bad, if you under vaccinate is bad, but if you vaccinate a little bit you can end up on the wrong strain. Great! /s
actually, the 'little bit' one is probably correct, unless you are in a susceptible group like the elderly then probably vaccinate a lot
we can also get better at predicting what each year's mutations are going to be, though that takes funding
but the idea that more vaccination is always better is technically not true, especially for a virus that is extremely good at mutating/shuffling its genome like the flu does.
but the reasons given by anti-vaxxers are generally BS.
Yeah I'm not in the anti-vaxxers thing, I was thinking more about the COVID vaccine we are given basically every year. After... I think 6 iterations (or 7?!) me and my family decided to go for the flu shot only, mainly because the flu shot can be given as a nasal shot, which is way less problematic.
Also the COVID shot is damn painful for some reason
This is why it's hard to make a 'super vaccine' for flu, becuase it takes many rounds of shots to retrain some people's immune systems once they've latched on to the wrong recipe for antibodies.