What can happen with getting vaccines like these ones is that they can promote and stimulate other medical biological problems in which people had existing and their bodies were already under stress fighting with.
This is a real minute percentage of the population as its been noted.
It should also be honestly accepted that these vaccines have been abnormally rushed to the public's use in comparison to how others been tested and evaluated in the past but still their documented effects have proven safe overall for 99% to those who have taken them.