MMR Vaccination: Benefits and Risks
MMR vaccination is strongly recommended for all children as it provides crucial protection against measles, mumps, and rubella with benefits that significantly outweigh the minimal risks. 1
Benefits of MMR Vaccination
Disease Prevention
- Measles Prevention: MMR vaccine is at least 95% effective in preventing clinical measles and 92% effective in preventing secondary cases among household contacts 2
- Mumps Prevention:
- 69-81% effective in preventing clinical mumps with Jeryl Lynn strain
- 70-75% effective with Urabe strain
- Two doses provide 83-88% effectiveness against laboratory-confirmed mumps 2
- Rubella Prevention: Provides protection against rubella, which can cause severe birth defects when contracted during pregnancy
Public Health Benefits
- Significant reduction in disease incidence in countries with successful vaccination programs 3
- Contributes to herd immunity, protecting vulnerable populations who cannot be vaccinated
- Helps prevent outbreaks and epidemics through high community vaccination rates
Vaccination Schedule
Recommended Timing
- First dose: 12-15 months of age (can be given as early as 12 months in high-risk areas) 1
- Second dose: 4-6 years of age (before kindergarten or first grade) 1
- Catch-up vaccination is recommended for unvaccinated individuals or those who have received only one dose 4
Administration Options
- For first dose at 12-47 months:
- Either MMR vaccine and separate varicella vaccine OR
- MMRV (combined) vaccine may be used
- CDC recommends separate MMR and varicella vaccines unless parent/caregiver specifically requests MMRV 1
- For second dose or first dose at ≥48 months:
- MMRV vaccine generally preferred over separate injections 1
Risks and Side Effects
Common Side Effects
- Injection site reactions (redness and pain) - approximately 12% of recipients 4
- Fever - 3-5% of recipients 4
- Mild rash
- These reactions typically occur about one week after vaccination 3
Rare but Significant Risks
- Febrile Seizures:
- Slightly increased risk within 6-11 days after vaccination
- Higher risk with MMRV vaccine compared to separate MMR and varicella vaccines in children 12-23 months (approximately one extra febrile seizure per 2,300-2,600 MMRV vaccine doses) 1
- Thrombocytopenic purpura: Small increased risk within 6 weeks after vaccination 2
- Aseptic meningitis: Rare risk, primarily with Urabe strain (not used in US) 2
Special Considerations
Contraindications
- History of anaphylactic reaction to neomycin, gelatin, or previous dose of vaccine
- Altered immunity (leukemia, lymphoma, immunodeficiency)
- Systemic immunosuppressive therapy
- Pregnancy 1
Precautions
- Recent receipt of antibody-containing blood products
- History of thrombocytopenia
- Moderate or severe acute illness
- Personal or family history of seizures (use separate MMR and varicella vaccines instead of MMRV) 1
Important Clinical Considerations
- Family history of seizures: For children with personal or family history of seizures, separate MMR and varicella vaccines are recommended rather than MMRV 1
- Timing with other vaccines: MMR vaccine may be administered simultaneously with other vaccines or at least 28 days before/after other live vaccines 1
- No link to autism: Evidence indicates MMR vaccine is unlikely to be associated with autism, asthma, diabetes, Crohn's disease, or other chronic conditions 2
- Long-lasting immunity: Vaccine provides long-lasting and possibly lifelong immunity 3
Documentation of Immunity
- Children without documentation of vaccination or other evidence of immunity should be vaccinated 1
- Two doses of MMR vaccine are required for school entry in most states 1
MMR vaccination is a critical component of pediatric preventive care with a favorable benefit-risk profile that has significantly reduced the burden of these potentially serious diseases worldwide.