Ensuring Vaccine Safety

The United States' long-standing vaccine safety system ensures that vaccines are as safe as possible. In fact, currently, the United States has the safest, most effective vaccine supply in its history.

Safety monitoring begins with the U.S. Food and Drug Administration (FDA), who ensures the safety, effectiveness, and availability of vaccines for the United States. Before a vaccine is approved by the FDA for use by the public, results of studies on safety and effectiveness of the vaccine are evaluated by highly trained FDA scientists and doctors. FDA also inspects the sites where vaccines are made to make sure they follow strict manufacturing guidelines.

Although most common side effects of a vaccine are identified in studies before the vaccine is licensed, rare adverse events may not be detected in these studies. Therefore, the U.S. vaccine safety system continuously monitors for possible side effects after a vaccine is licensed. When millions of people receive a vaccine, less common side effects that were not identified earlier may occur.

If a link is found between a possible side effect and a vaccine, public health officials take appropriate action. They will weigh the benefits of the vaccine against its risks to determine if recommendations for using the vaccine should change.

Learn more about the Vaccine Adverse Event Reporting System (VAERS).

Why is it important to monitor vaccine safety?

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