MMR Vaccination for Adults Without Documented Immunity
Adults lacking documented immunity to measles, mumps, and rubella should receive 2 doses of MMR vaccine separated by at least 28 days. 1, 2, 1
General Recommendation
For adults born in 1957 or later without evidence of immunity, the standard approach is straightforward:
- First dose: Administer immediately upon identification of lack of immunity
- Second dose: Give minimum 28 days after the first dose 1
This two-dose series applies to all adults who cannot provide acceptable evidence of immunity, regardless of whether they believe they were previously vaccinated 3.
What Constitutes Acceptable Evidence of Immunity
Before vaccinating, verify the adult truly lacks immunity. Acceptable evidence includes 1, 3:
- Laboratory confirmation of immunity (serologic testing showing IgG antibodies)
- Documentation of 2 appropriately spaced MMR doses (minimum 28 days apart)
- Laboratory confirmation of disease (note: physician diagnosis alone is NOT acceptable for measles or mumps; only laboratory-confirmed disease counts)
- Birth before 1957 (with important exceptions below)
High-Risk Groups Requiring 2 Doses
Certain adults must receive 2 doses regardless of birth year 1, 4:
- Healthcare personnel (even those born before 1957 without laboratory evidence of immunity should be considered for 2 doses)
- Students in postsecondary educational institutions
- International travelers
- Persons in outbreak settings
For healthcare workers born before 1957 who lack laboratory evidence of immunity, facilities should strongly consider administering 2 doses at the appropriate interval 2.
Special Considerations
Women of childbearing age: Rubella immunity should be determined regardless of birth year. If non-immune and not pregnant, vaccinate immediately. If pregnant without immunity, administer MMR upon completion or termination of pregnancy before hospital discharge 1, 4.
Persons with previous killed measles vaccine (1963-1967): These individuals require 2 doses of current MMR vaccine regardless of previous vaccination history 1.
Important Caveats
Serologic testing after vaccination: Recent evidence suggests that some adults may not achieve seroconversion after 2 doses 5. However, current ACIP guidelines do not recommend routine serologic testing after vaccination or additional doses beyond the 2-dose series for immunocompetent adults 3. The 2-dose series is considered adequate for protection even if antibody titers are low or undetectable.
Waning immunity: Emerging data shows immunity may wane 10-15 years post-vaccination 6, but no third dose is currently recommended for routine use in immunocompetent adults.
Contraindications: Do not administer to pregnant women or severely immunocompromised individuals 1, 3.
The evidence consistently supports the 2-dose regimen across multiple ACIP guideline updates from 2007-2014, with the most recent comprehensive recommendations emphasizing this approach for all adults without documented immunity 1, 2, 1, 3.