Vaccine Safety

Vaccines are the best way to prevent serious illness and death from many infectious diseases. The Food and Drug Administration (FDA) adheres to rigorous testing standards before licensing vaccines.

Vaccines are developed through the same general process used to develop drugs and medicines. more A sponsor who wishes to begin clinical trials with a vaccine must apply to FDA. In their application, they must describe the vaccine, how it is manufactured, and the quality control tests that are done. The applications must also include information about the vaccine's safety and the results of testing in animals.

If the application is approved, the vaccine can be tested on people during clinical trials. These trials are typically done in three phases. Phase 1 studies are performed in a small number of closely monitored subjects. Phase 2 studies may enroll hundreds of subjects. Finally, Phase 3 trials typically enroll thousands of people. These trials are used to document the effectiveness of the vaccine. They also provide important additional safety data required for licensing. At any stage of the studies in animals or humans, if data raise significant concerns about either safety or effectiveness, FDA may request additional information or studies, or may halt ongoing clinical studies.

After reviewing clinical trial results and the proposed vaccine label, inspecting the facility where the vaccine will be made, and reviewing the vaccine production process, the FDA may decide to license the vaccine.

Once licensed, vaccines continue to be closely monitored through the national Vaccine Adverse Event Reporting System (VAERS) and Vaccine Safety Datalink (VSD) Project. Anyone can report a health problem to VAERS. Any problem with a vaccine may prompt further investigation by the Centers for Disease Control and Prevention and the Food and Drug Administration.

Leaders in the field of public health, such as the Centers for Disease Control and Prevention, the Public Health Service, and the nation's physicians (e.g., the American Academy of Pediatrics, the American Medical Association, and American Academy of Family Physicians continue to recommend vaccines for children, adolescents, and adults to prevent disease.

Trusted sources of information

People with questions or concerns about vaccine safety should contact their healthcare providers. Information found online should not replace the information given by a healthcare provider. However, there are several trusted organizations that parents and patients can turn to for additional information.