Management of Low MMR Titers in Adults
Adults with low MMR titers should receive vaccination according to their specific risk category, with 1-2 doses of MMR vaccine depending on their circumstances, regardless of previous vaccination history. 1
Assessment of Immunity Status
Before determining the vaccination approach, evidence of immunity should be established:
Acceptable evidence of immunity includes:
- Laboratory evidence of immunity or laboratory confirmation of disease
- Documentation of appropriate vaccination (≥1 dose for most adults, 2 doses for high-risk groups)
- Birth before 1957 (except for healthcare personnel) 1
Not acceptable as evidence of immunity:
- Self-reported or physician-diagnosed disease without laboratory confirmation 2
Vaccination Recommendations Based on Risk Categories
General Adult Population (born 1957 or later)
- One dose of MMR if no evidence of immunity and no prior documentation of vaccination 1
- No routine testing of titers needed after vaccination in general population
High-Risk Adults
Adults in the following categories should receive two doses of MMR vaccine at least 28 days apart if they have low titers or no documentation of immunity:
- Healthcare personnel
- Students in postsecondary educational institutions
- International travelers
- Persons living in communities experiencing outbreaks 1
Special Considerations
Healthcare Personnel
- Healthcare workers born before 1957 who lack laboratory evidence of immunity should receive 2 doses of MMR for measles and mumps, or 1 dose for rubella 1
- This group should not rely on birth year as presumptive evidence of immunity 1
Women of Childbearing Age
- Rubella immunity should be determined regardless of birth year
- Women with low rubella titers who are not pregnant should receive 1 dose of MMR 1
- Pregnant women with low titers should be vaccinated postpartum before discharge 1
- Avoid pregnancy for 4 weeks after vaccination 1
Effectiveness and Safety Considerations
- MMR vaccination in previously immunized adults has been shown to effectively boost antibody levels, with the greatest increases occurring in those with the lowest pre-immunization titers 3
- Recent studies show that mumps antibody titers may wane more quickly than measles or rubella, potentially explaining recent mumps outbreaks among previously vaccinated adults 4
- MMR vaccine is generally safe in adults with low rates of adverse events. In a study of 785 adult travelers, only 25.2% reported any adverse events, most of which were mild 5
Common Pitfalls to Avoid
Don't assume prior infection provides immunity without laboratory confirmation - Clinical diagnosis of past infection is no longer considered acceptable evidence of immunity 2
Don't overlook the need for vaccination in adults born before 1957 who work in healthcare - This group should still be vaccinated if titers are low 1
Don't delay vaccination in women of childbearing age with low rubella titers - Congenital rubella syndrome is preventable with timely vaccination 1
Don't assume a single childhood dose provides lifelong immunity - Waning immunity, particularly to mumps, has been documented 4
By following these guidelines, clinicians can effectively address low MMR titers in adults and help prevent outbreaks of these vaccine-preventable diseases.