If you or your child has had the Influenza FLU ( inactivated ) Vaccine, you may develop the following side effects
In my own experience, it seems to be safer to take your child in for a vaccination when they are not already sick/ill and be sure never to give them fever medication before their vaccination.
Side effects for other Vaccines found here https://www.cdc.gov/vaccines/vac-gen/side-effects.htm