Vaccine Safety Assurance

Vaccines are held to a very high safety standard. They undergo careful safety testing before they are licensed, and they are monitored for safety throughout all stages of use. Parents can learn more about how their child’s vaccines are developed and tested for safety by watching this video, The Journey of Your Child's Vaccines.

CDC Infographic: The Vaccine Life Cycle

Post-Licensure Monitoring

Vaccine Safety Monitoring is conducted by the federal Immunization Safety Office.
The four main ways vaccines are monitored for safety include:

Vaccine Adverse Event Reporting System (VAERS)
The Vaccine Adverse Event Reporting System (VAERS) is a national program which collects information about adverse events associated with vaccinations for monitoring the safety of vaccines used in the United States.

Vaccine Safety Datalink (VSD)
The VSD is a collaborative project between CDC’s Immunization Safety Office and eight health care organizations. VSD monitors possible adverse events, when new vaccines are licensed or when there are new recommendations developed for a vaccine.

Clinical Immunization Safety Assessment (CISA) Project
CISA is a national network of vaccine safety experts from CDC’s Immunization Safety Office, seven medical research centers and other partners. US healthcare providers with vaccine safety questions about a particular patient, that is not addressed by Advisory Committee on Immunization Practices (ACIP) guidelines can contact CDC to request a CISA evaluation at

Emergency Preparedness for Vaccine Safety

CDC’s Immunization Safety Office (ISO) prepares for emergencies by ensuring that robust systems are in place to rapidly monitor vaccine safety in the event of an emergency vaccination program.
Emergency Preparedness for Vaccine Safety

Vaccine-specific Safety Research

Each of the common vaccines have a proven safety track record and research behind them.
Safety Information by Vaccine

Multiple Vaccines and the Immune System

Getting several vaccines at the same time is safe and ensures the best protection at the right time. 
Multiple vaccines at the same time

Common Misconceptions

Lots of questions come up about vaccines. Here are science-based answers to some common ones. 
Common Vaccine Safety Questions