As with all medications, there are risks and side effects with vaccines, although serious side effects are mostly rare. There are various tools and programs to monitor and study vaccine safety, either before or after vaccine licensure.
This section explains how vaccine safety research and monitoring is done.
Because of the success of vaccines, vaccine-preventable diseases aren’t feared anymore and concerns about vaccine safety are common. But these diseases are not gone.
The VSD project was created in 1990 by the Centers for Disease Control and Prevention (CDC) and currently involves partnerships with 8 large health maintenance organizations (HMOs) to continually monitor vaccine safety.
When an adverse event occurs after vaccination, it needs to be determined whether the adverse event was caused by the vaccine or whether it was just coincidental in time with the administration of the vaccine—that is, it was going to happen anyway. How can researchers determine if a vaccine causes a particular disease or not?
The Vaccine Adverse Event Reporting System (VAERS) is a national system for reporting possible adverse reactions or side effects after any US-licensed vaccine. This article explains how VAERS works and describes its strenghts and limitations.