I’m thinking that the flu vaccine acts as a crutch for the immune system that leaves it unprepared to fight off a similar virus not included in the shot.
What doesn’t kill me only makes me stronger.
I don't know if I would describe the shot as a "crutch," but instead, I would call it a "kick-start" for the immune system. It allows the body to start producing antibodies that can help defend against the flu should the person be exposed to the flu later that season.
Read that last part carefully, Freepers. So many people are misinformed, or have unrealistic expectations about what the flu shot does or is supposed to do. It does not prevent you from getting the flu; if you have the flu shot and allow enough time to develop antibodies (about two weeks after receiving the shot) and are later exposed, the vaccine can help your body fight off the flu faster and with less severe symptoms.
Of course, predicting the strain that will emerge season by season is part science, part art. There is some data that suggest even similar vaccines may be partially effective, such as what's going on this year.