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Vaccine Safety

Family talking to doctor about vaccine safety concerns

In the United States, a number of safeguards are required by law to help ensure that the vaccines we receive are safe.

The safety of vaccines is often a topic of media stories and blog postings. This attention may make you wonder, “How do we know our vaccines are safe?” Here are some important things to know about vaccine safety.

1. The safety of vaccines is thoroughly studied before they are licensed for public use.

Clinical trials are conducted to evaluate the safety and effectiveness of a vaccine before it can be brought to market. Vaccines are first tested in laboratory studies and animal studies. If the results indicate the vaccine is safe, additional testing in people must be done before the vaccine can be approved by the Food and Drug Administration (FDA). Learn more about vaccine clinical trials.

2. There is a strong system in place to help scientists monitor the safety of vaccines.

Multiple systems are used to monitor the safety of vaccines after they have been licensed for public use. These systems, such as the Vaccine Adverse Event Reporting System (VAERS), the Vaccine Safety Datalink (VSD), and the Clinical Immunization Assessment (CISA) project, complement each other and help scientists monitor the safety of vaccines and conduct vaccine safety research. Learn more about how vaccines are monitored for safety.

Doctor injecting an older patient with a vaccine

Making sure vaccines are safe is a priority for CDC.

3. Like any medicine, vaccines can cause side effects. However, serious adverse events from vaccines are rare.

Most side effects from vaccines, such as pain and redness at the injection site, are mild and go away quickly on their own. Serious adverse events are rare. If you have questions or concerns about a vaccine, talk with your healthcare provider. Learn more about the safety of recommended vaccines.

4. Receiving combination vaccines or several different vaccines during one visit is safe and offers the quickest protection again multiple diseases.

It is safe to receive several different vaccines during one visit. Also, combination vaccines are as effective as individual vaccines. Learn more about multiple vaccines and the immune system.

5. You can play a role in monitoring the safety of vaccines.

Anyone can submit a report to VAERS, the vaccine safety monitoring system managed by CDC and FDA. The report of an adverse event to VAERS does not mean that a vaccine caused the event. It only indicates that the event occurred after the vaccine was administered. Proof that the event was caused by the vaccine is not required in order to send a report to VAERS. Learn more about submitting a report to VAERS.

Health officials are continuously monitoring information from many sources for any clues that a particular vaccine may cause an adverse health event. As a result, the United States has one of the best vaccine safety programs in the world.

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