My father got his first flu vaccine shot when he was about 62, and immediately came down with the flu. He was quite ill for several days. (I doubt that he previously had any other vaccinations for many years, maybe none). He never had another vaccination, and never got ill again.
He had a good constitution and never looked after himself. He smoked and drank and never exercised at all. He died at 87 of ‘old age’, so the death certificate said.