MMR Vaccine Schedule
Administer the first dose of MMR vaccine at 12-15 months of age and the second dose at 4-6 years of age. This two-dose schedule is the current standard recommendation endorsed by ACIP, AAP, and AAFP 1, 2.
Routine Childhood Schedule
First Dose
- Timing: 12-15 months of age (minimum age: 12 months) 2
- The vaccine can be given as early as 12 months, though seroconversion rates are slightly higher at 15 months (98%) versus 12 months (93-96%) 3
- This difference has limited clinical significance because the second dose compensates for primary vaccine failure 3
Second Dose
- Timing: 4-6 years of age (typically before kindergarten entry) 3, 1
- Minimum interval: The second dose may be administered earlier than 4 years, provided at least 28 days (4 weeks) have elapsed since the first dose 4, 2
- The primary benefit of the second dose is reducing the approximately 5% of children who fail to respond to the first dose due to primary vaccine failure 3
Special Situations
High-Risk Areas
In counties with large inner-city populations, recent measles outbreaks among unvaccinated preschoolers, or >5 measles cases among preschoolers in each of the last 5 years, administer the first dose at exactly 12 months rather than waiting until 15 months 3.
Early Vaccination (6-11 Months)
- Infants vaccinated before 12 months (such as during outbreaks or before international travel) must receive two additional doses 2:
- First routine dose at 12-15 months
- Second dose at 4-6 years
- This early dose does not count toward the two-dose series 2
Post-Exposure Prophylaxis
Administer MMR vaccine within 72 hours after measles exposure for unvaccinated individuals without contraindications 2.
Catch-Up Vaccination (≥7 Years)
For unvaccinated individuals aged ≥7 years, administer two doses separated by at least 28 days 4.
Adults
General Population
- Born before 1957: Generally considered immune; no vaccination required 5
- Born 1957 or later: Require at least one dose of MMR unless they have laboratory evidence of immunity or documented vaccination 5
High-Risk Adults (Require 2 Doses)
The following groups need two doses of MMR separated by at least 28 days 5:
- Healthcare workers
- College/post-secondary students
- International travelers
Women of Childbearing Age
All women of childbearing age should have documented rubella immunity (one dose of MMR is sufficient for rubella protection). If no evidence of immunity exists and the woman is not pregnant, vaccinate immediately. If pregnant without immunity, vaccinate upon completion or termination of pregnancy before hospital discharge 5, 3, 5.
Key Clinical Considerations
Common Pitfall: Do not restart the vaccine series regardless of time elapsed between doses. If the schedule is interrupted, simply continue where it was stopped 4.
Documentation: Acceptable evidence of immunity includes laboratory confirmation of disease or immunity, or documented age-appropriate vaccination—but physician-diagnosed disease is no longer accepted as evidence of immunity for measles and mumps 6.
HIV-Infected Children: Should receive MMR at 12 months if they do not have current severe immunosuppression 3.