How is MMR (Measles, Mumps, and Rubella) vaccination confirmed through testing?

Confirming MMR Vaccination Through Testing

Laboratory evidence of immunity through serologic testing is an acceptable method to confirm MMR vaccination status when documentation is unavailable. 1

Presumptive Evidence of Immunity

Immunity to measles, mumps, and rubella can be established through:

• Documentation of age-appropriate vaccination with MMR vaccine 1
• Laboratory evidence of immunity (serologic testing) 1
• Laboratory confirmation of disease 1
• Birth before 1957 (except for healthcare personnel and women who could become pregnant) 1

Serologic Testing Methods

For Measles:

• Any licensed serologic assay showing measles IgG antibodies above the standard positive cutoff value is acceptable evidence of immunity 1
• Enzyme immunoassay (EIA) is the most commonly used method 1

For Mumps:

• Demonstration of mumps IgG antibody by any commonly used serologic assay is acceptable evidence of immunity 1
• Persons with "equivocal" results should be considered susceptible unless they have other evidence of immunity 1

For Rubella:

• Any antibody level above the standard positive cutoff value of a licensed assay can be considered evidence of immunity 1
• Enzyme-linked immunosorbent assay (ELISA) has largely replaced hemagglutination inhibition (HI) testing 1

Interpretation of Results

Positive Results:

• Indicates immunity to the respective disease 1
• Long-term immunity is expected after vaccination, with studies showing protection lasting at least 10 years 2

Negative or Equivocal Results:

• For persons with documented MMR vaccination but negative/equivocal rubella IgG levels, no additional doses are needed - they should be considered immune 1
• For persons with no documentation of vaccination, a dose of MMR vaccine should be administered 1
• Documented age-appropriate vaccination supersedes negative serologic test results 1

Special Considerations

• For healthcare personnel, prevaccination antibody screening before MMR vaccination is not necessary unless the medical facility considers it cost-effective 1
• During outbreaks, serologic screening before vaccination is not recommended because rapid vaccination is necessary 1
• In persons who initially developed antibodies detectable by older methods (like HI) but later appeared to "lose" this antibody, almost all still had antibody detectable by more sensitive tests 1

Vaccine Effectiveness and Immunity

• Seroconversion rates of 95-100% are achieved for each component of the MMR vaccine 3
• Even when antibody levels decline over time, protection against disease is largely retained 2
• Mumps antibodies tend to wane more than measles and rubella antibodies in both 2-dose and 3-dose recipients 2

Common Pitfalls to Avoid

• Do not rely on clinical diagnosis of past infection, especially for rubella, as it is unreliable 1
• Do not retest persons with documented vaccination history who have equivocal serologic results - they should be considered immune 1
• Do not assume that birth before 1957 guarantees mumps immunity, especially during outbreaks 1
• Do not use serologic testing to determine immunity in severely immunocompromised persons, as they may not mount an adequate antibody response 1