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Be Informed

Vaccines are held to the highest standard of safety. The United States currently has the safest, most effective vaccine supply in history. Vaccines undergo a rigorous and extensive evaluation program to determine safety and effectiveness. If a vaccine does receive approval by FDA, it is continuously monitored for safety and effectiveness.

Read more about common questions related to vaccine safety, including:

Many partners work together to make sure vaccines are safe. Government health scientists work with manufacturers, health care providers, academia, and global health groups such as the World Health Organization to offer a comprehensive vaccine safety system. At the Department of Health and Human Services, primarily three agencies are involved in vaccine safety:

  • Centers for Disease Control and Prevention (CDC)
  • Food and Drug Administration (FDA)
  • National Institutes of Health (NIH)

Vaccines undergo extensive testing and rigorous evaluation by FDA and are approved only after FDA has determined that the scientific information supports safety and effectiveness. Once a vaccine is approved, FDA regularly inspects vaccine manufacturing facilities to make sure strict regulations are followed. Vaccines are manufactured in batches called lots and vaccine manufacturers must test all lots of a vaccine to ensure safety, purity, and potency. Vaccine lots cannot be distributed to the public until released by FDA.

Scientists from FDA and CDC work closely to monitor reports of vaccine side effects (adverse events) after they are approved and used widely. FDA and CDC take all reports seriously, and work together to evaluate and address any potential problems.


After talking with parents across the country, CDC put together this short video to help answer the tough questions that real moms had about childhood immunizations. Understanding the importance of vaccines is crucial for you to protect your children’s health. To watch the video, click on the arrow in the embedded video below. You can also read the video script

Get The Picture: Childhood Immunizations

Source: National Center for Immunization and Respiratory Diseases
Running Time: (6:27) Release Date: 4/13/2009

How to Report Adverse Events

Vaccines, like any medication, may cause side effects. If you think that you or your child does have a serious reaction, first contact your doctor or other health care provider. Then, if you would like to learn more, read about the two programs below—VAERS and the National Vaccine Injury Compensation Program. Most people will never need these programs, but they are there if you do.

  • VAERS. This stands for the Vaccine Adverse Event Reporting System. It is a system for reporting adverse events following receipt of a vaccine. If you or your child has an unusual medical condition within a few days after getting a vaccine, you or your provider should report it to VAERS even if you don’t know whether it was related to the vaccine. One of the jobs of VAERS is to collect these reports and use the data to help identify serious adverse reactions that may require further investigation. Your provider will usually file a VAERS report for you. However, you can also file a report yourself. For more information, see the VAERS website at www.vaers.hhs.gov.
  • Vaccine Injury Compensation Program. If you believe you or your child was seriously injured by a vaccine, there is a no-fault federal program that may help compensate you for his or her care. To learn more about the Vaccine Injury Compensation Program, see their website at www.hrsa.gov/vaccinecompensation.

Last reviewed: April 2015