MMR Vaccine Safety Studies

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Due to high vaccination rates, outbreaks of measles, mumps, and rubella in the U.S. are not as common as they were before the vaccine began being used. However, these diseases still appear in the U.S. and people who decide not to vaccinate their children because of religious or personal beliefs put their children and others at risk for getting these diseases.

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  • The MMR vaccine protects against dangerous, even deadly, diseases.
  • The most common adverse events following the MMR vaccine are pain where the vaccine is given, fever, a mild rash, and swollen glands in the cheeks or neck.
  • Studies have shown a small increased risk of febrile seizures occurs among children who are younger than 7 years old approximately 8-14 days after vaccination at a rate of one for every 3,000-4,000 children vaccinated with MMR vaccine. This is compared to children not vaccinated during the preceding 30 days.
  • No published scientific evidence shows any benefit in separating the combination MMR vaccine into three individual shots.
  • Measles outbreaks can occur in communities with a high number of unvaccinated people. Maintaining high overall MMR vaccination rates is needed to continue to limit the spread of measles.

Because signs of autism may appear around the same time children receive the MMR vaccine, some parents may worry that the vaccine causes autism. Vaccine safety experts, including experts at CDC and the American Academy of Pediatrics (AAP), agree that MMR vaccine is not responsible for recent increases in the number of children with autism. In 2004, a report by the Institute of Medicine (IOM) concluded that there is no link between autism and MMR vaccine, and that there is no link between autism and vaccines that contain thimerosal as a preservative.

MMR Vaccine Safety Research

Many carefully performed scientific studies have found no link between MMR vaccine and autism. These studies include:

  • A September 2008 case-control studyexternal icon published in Public Library of Science (PLoS) was conducted in 2004-2008 to determine whether results from an earlier study that claimed to find measles virus RNA in the intestinal tissue of a specific group of autistic children could be confirmed. The results could not be confirmed, and no link between MMR and autism was found.
  • An April 2006 study conducted by the National Institute of Child Health and Human Development (NICHD) of NIH and the CDC assessed data from 351 children with autism spectrum disorders and 31 typically-developing children. The study did not find a link between MMR vaccination and autism. The results were published in the Journal of Autism and Developmental Disorders.
  • A February 2004 case-control studyexternal icon examined the possible relationship between exposure to the MMR vaccine and autism in Atlanta, Georgia. The results were published in Pediatrics.
  • A November 2002 study by CDC and the Danish Medical Research Council that followed more than 500,000 children over 7 years and found no association between MMR vaccination and autism. The results were published in the New England Journal of Medicine.
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Page last reviewed: June 8, 2020
Content source: Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of Healthcare Quality Promotion (DHQP)