MMR Vaccine Dosing
Two doses of MMR vaccine are recommended for routine vaccination, with the first dose at 12-15 months and the second dose at 4-6 years of age, separated by at least 28 days. 1, 2
Standard Dosing Schedule
Routine Childhood Vaccination
- First dose: 12-15 months of age 1, 3, 2
- Second dose: 4-6 years of age (before kindergarten or first grade) 1, 3, 2
- Minimum interval between doses: 28 days 1, 3, 2
- Dose volume: 0.5 mL administered subcutaneously 1, 3
The two-dose schedule is critical because approximately 5% of vaccinees experience primary vaccine failure after the first dose, and almost all persons who don't respond to the first dose will respond to the second dose. 1, 3
Catch-Up Vaccination
- Previously unvaccinated children and adolescents: Two doses separated by at least 28 days 1
- No need to restart the series regardless of time elapsed between doses if a child is behind schedule 2
Special Populations
Adults
- Adults born in 1957 or later without evidence of immunity: At least one dose 1, 2
- Adults at higher risk (healthcare workers, international travelers, college students): Two doses separated by at least 28 days 2, 4
- Adults born before 1957: Generally considered immune; only one dose if vaccination is indicated 3
Infants (6-11 months)
- International travel or outbreak settings: One dose before travel or during outbreak 1, 3, 2
- Important caveat: This early dose does not count toward the routine two-dose series; these infants still need two full doses starting at 12-15 months 1
Special Circumstances
Mumps Outbreak Settings
- Third dose indication: A third dose of MMR is recommended for persons identified by public health authorities as being at increased risk during mumps outbreaks 3
- This is the ONLY routine indication for a third dose - it does not apply to measles or rubella outbreak settings 3
Post-Exposure Prophylaxis
- Measles exposure in unvaccinated persons: One dose of MMR within 72 hours of exposure, followed by completion of the two-dose series 3
Critical Clinical Pearls
Documentation Supersedes Serology
- Individuals with two documented doses of MMR are considered immune regardless of subsequent serologic testing results 1
- Do not routinely order serologic testing after two documented MMR doses, as antibody titers can wane over time without loss of immune memory 1
- Do not revaccinate based solely on negative titers in someone with proper documentation of two MMR doses 1
Administration Considerations
- MMR can be administered simultaneously with other vaccines at different anatomic sites 1
- Live virus vaccines not given on the same day should be separated by ≥4 weeks 1, 2
- If immune globulin is administered, delay subsequent MMR vaccination for 5-6 months 1