Consider two possibilities, both fairly remote and I have absolutely no reason to believe that they're real.

First, suppose that the people who suffer badly from the vaccines/virus do so 100% because of some factor that comes and goes, such as having slept badly. In this case, suffering badly from a vaccine does not mean that you would suffer badly from the disease.

Second, suppose that the people who suffer badly do so 100% because of some genetic factor, such as having a single gene for a particular recessive disease. In this case, if you suffer badly from a vaccine it means that you've saved yourself even worse suffering when the disease finally finds you.