Having a "reaction" after a vaccination because they had an issue they didnt previously know about perhaps.
This isnt the same as vaccinations cause autism crowd,bu4 people get lumped in with that crowd.
Which is why i cited the cdc stating that seizures,coma , brain damage are ,though rare, real impacts of some vaccinations on people. Those happen because people didnt know that would happen otherwise they wouldnt have vaxed their child.