Understanding Vaccines and Vaccine Safety

The webpages below provide information about vaccine testing, safety, monitoring, and the process for establishing the U.S. immunization schedule.

Understanding MMR Vaccine Safety

Safety information on Measles, Mumps, Rubella (MMR) Vaccine addresses common questions about the MMR vaccine, including those related to side effects and effectiveness.

Understanding How Vaccines Work

Understanding How Vaccines Work explains how the immune system responds to vaccines to build immunity.

Ensuring the Safety of Vaccines in the United States

Ensuring the Safety of Vaccines in the United States outlines how vaccines are tested for safety before being licensed for use and how their safety is monitored after licensure.

Thimerosal and Vaccines

Questions and concerns on thimerosal and vaccines explains what thimerosal is, why it is used as a preservative in multi-dose vials of flu vaccine, and highlights conclusions from studies examining thimerosal safety in vaccines.

Autism and Vaccines

Autism and Vaccines explains that vaccines do not cause autism. Some people have had concerns that Autism Spectrum Disorder (ASD) might be linked to the vaccines children receive, but studies have shown that there is no link between receiving vaccines and developing ASD.

The Advisory Committee on Immunization Practices (ACIP)

The Advisory Committee on Immunization Practices (ACIP) and the Childhood Immunization Schedule provides details about the group of experts who make U.S. immunization recommendations.

Page last reviewed: August 17, 2021