The flu vaccine has been studied very carefully and is safe. The CDC and FDA continue to monitor the safety of vaccines including all the influenza vaccinations available annually (as with each year the prevalence of different strains change). The CDC uses 3 systems to monitor the safety of vaccines including the Vaccine Adverse Event Reporting System (VAERS), Vaccines Safety Datalink (VSD), and the Clinical Immunization Safety Assessment Project (CISA). The immunization may cause mild symptoms, like soreness and a low fever, but that is not influenza. These symptoms usually go away a day or two after vaccination. You cannot get the flu from the flu shot.