How does FDA assess the safety of vaccines?

Vaccines undergo rigorous and extensive testing to determine their safety and effectiveness. Highly trained scientists and medical personnel at FDA carefully review all of the information in a marketing application before a vaccine can be approved for use by the public.

Following approval, FDA also carefully monitors the quality of vaccines—all manufactured lots must pass tests before they can be used. And as with all manufacturers of medical products, vaccine manufacturers must follow strict manufacturing standards. In addition, FDA conducts routine inspections of manufacturing sites.

FDA also works closely with the Centers for Disease Control and Prevention (CDC) to monitor reports of side effects (adverse events) of vaccines. FDA and CDC take all reports seriously, and work together to evaluate and address any potential problems.