From the Guidelines
The MMR vaccine has an excellent long-term safety profile with minimal serious risks, and severe long-term complications from the MMR vaccine are extremely rare. The most significant documented long-term risk is a very rare chance (about 1 in 1 million doses) of developing a severe allergic reaction or a condition called thrombocytopenia, where blood platelets temporarily decrease 1. There is no credible scientific evidence linking the MMR vaccine to autism, developmental disorders, or other chronic conditions, despite extensive research investigating these concerns. The vaccine contains weakened forms of the measles, mumps, and rubella viruses that stimulate immunity without causing disease. For most people, any side effects are limited to mild, short-term reactions like fever or rash that resolve completely within days. Some key points to consider about the MMR vaccine include:
- The risk of febrile seizures is higher after the first dose of MMRV vaccine compared to MMR vaccine and varicella vaccine administered separately, but this risk is still very low 1.
- The long-term benefit of protection against these potentially serious diseases far outweighs the minimal risks associated with vaccination, as established through decades of use and monitoring in hundreds of millions of people worldwide 1.
- The MMR vaccine is not associated with an increased risk of long-term health impairment, such as epilepsy or neurodevelopmental delays, even in the rare cases where febrile seizures occur 1.
- The vaccine's safety profile has been extensively studied, and the evidence consistently shows that the benefits of vaccination outweigh the risks 1. Therefore, the MMR vaccine is a safe and effective way to protect against measles, mumps, and rubella, and its use is recommended for individuals of all ages who are eligible for vaccination.
From the Research
Long-term Risks of the Measles, Mumps, and Rubella (MMR) Vaccine
The MMR vaccine has been associated with several adverse events, including:
- Seizure
- Fever
- Immune thrombocytopenia purpura (ITP) 2, 3
- Ataxia
- Arthritis
- Meningitis/encephalitis
- Acute disseminated encephalomyelitis
- Kawasaki disease 2
Risk of Febrile Seizures
The risk of febrile seizures after MMR vaccination is higher among older children (12-23 months) than among younger children (12-15 months) 4. The combination measles, mumps, rubella, and varicella vaccine is associated with a 2-fold increased risk of febrile seizures 7 to 10 days following immunization compared with the separately administered measles, mumps, and rubella and varicella vaccines 2, 4.
Risk of Immune Thrombocytopenia Purpura (ITP)
The MMR vaccine is associated with an increased risk of ITP, particularly among children aged 12-15 months 3. The incident rate ratio for ITP was highest for children aged 12-15 months at 7.10, and 76% of ITP cases in children aged 12-23 months were attributable to MMR vaccination 3.
Risk of Other Adverse Events
The MMR vaccine has not been associated with an increased risk of other adverse events, such as:
- Anaphylaxis
- Ataxia (in fact, the risk of ataxia was lower after MMR vaccination) 2
- Arthritis
- Meningitis/encephalitis
- Acute disseminated encephalomyelitis
- Kawasaki disease 2
Age-Specific Risks
The risk of adverse events after MMR vaccination varies by age: