All I know ow from redneck medical observation 8s that getting a flu shot increases your chance of getting the flu. Why is pure speculation, but I suspect dumping a boatload of viruses directly into your blood stream must ay he’ll with your immune system.
Also from observations of all the anti vaxers saying on threads that they don’t get the vaccine and have not had the flu in 20 years and all the vaxers saying they do, it is an obvious statistical elephant in the room.
Last flu I got, I had a shot to protect me. I caught the flu two weeks after getting 5he shot. That was the last flu shot I took, in the late 80’s.
Your milage may vary.
Are you one of those people who is really smart on political things and really dumb on scientific things?