Studies have shown that deaths from COVID among children are incredibly rare, and more kids die from the flu than from COVID. People with auto-immune diseases, transplant patients and certain kinds of cancer have always been more susceptible to illness. Never have we mandated flu vaccines before, and those people would be equally as susceptible. However, I think you should be asking yourself.. if an mRNA vaccine presents auto-immune response, who is to say that isn't harming those being forced to be vaccinated? There is little to be understood about many auto-immune diseases, just look at fibromyalgia, which has often been labeled as a psychological condition and not a physical one. Many doctors still don't believe it is real, and if you use it for a disability claim it is difficult to prove.
If what you're saying is to be considered, then it must also be considered that the vaccine could have subtle side effects that may not be immediately known and later exhibit themselves as incredibly hard to diagnose and nearly impossible to detect illnesses.