Chapter 21: Surveillance for Adverse Events Following Immunization Using the Vaccine Adverse Event Reporting System (VAERS)

Vaccinations are usually administered to healthy persons and often are mandated; therefore, they are held to a higher standard of safety than other medical products.4 However, as with all medical products, no vaccine is perfectly safe or effective. Vaccines can cause minor adverse effects such as fever or local reactions at the injection site. Rarely, they can cause serious adverse effects such as febrile seizures or severe allergic reactions. Adverse events (AE) can also occur coincidentally after vaccines (i.e. they would have occurred in the absence of vaccination). To reduce the occurrence of vaccine AE and maintain public confidence in vaccines, it is important to improve the understanding of vaccine safety. Robust vaccine safety monitoring may foster the discovery of adverse events associated with vaccination, and thus the development and use of safer vaccines and recommendations to minimize the risk of AE after vaccination (e.g., define new recommendations, contraindications and precautions).5 One way to enhance our understanding of vaccine safety is to improve surveillance for vaccine AE.