Vaccine Adverse Effects: An Overview

Vaccines are one of the most successful medical advances in modern times. Patients are increasingly questioning the necessity of immunizing themselves and their families, and family physicians should be aware of the risks and benefits of recommended immunizations to accurately counsel about adverse effects and address vaccine hesitancy. Vaccines are associated with local adverse reactions, such as pain and redness. Thimerosal is currently used only in multidose vials of influenza vaccine; exposure to thimerosal through vaccines is not associated with adverse neurologic outcomes. The measles-mumps-rubella vaccine is not associated with autism spectrum disorder. The respiratory syncytial virus vaccine does not increase the risk of stillbirth, infant death, birth defects, or growth restriction when administered during pregnancy. COVID-19 vaccine minimally increases the risk of myocarditis and pericarditis. Physicians should counsel patients and guide them to credible resources if patients are considering vaccine refusal. The Vaccine Adverse Event Reporting System and National Vaccine Injury Compensation Program track adverse events from vaccines; the National Vaccine Injury Compensation Program provides compensation for documented harms from vaccinations.