From the Guidelines
I strongly recommend testing for IgG mumps antibodies before deciding on vaccination for a patient with low Immunoglobulin M (IgM) antibody levels. A low IgM antibody level alone is not sufficient to determine immunity status, as IgM antibodies typically indicate a recent infection or vaccination, while IgG antibodies reflect long-term immunity 1. If IgG testing reveals adequate antibody levels, vaccination is unnecessary as the patient already has immunity. However, if IgG levels are low or absent, the MMR (measles, mumps, rubella) vaccine would be appropriate regardless of IgM status. The standard approach to determining immunity involves assessing IgG antibody levels, as stated in the recommendations of the advisory committee on immunization practices (ACIP) 1. Some key points to consider in this decision include:
- The demonstration of mumps IgG antibody by any commonly used serologic assay is acceptable evidence of mumps immunity 1
- Persons who have an "equivocal" serologic test result should be considered susceptible to mumps unless they have other evidence of mumps immunity 1
- The MMR vaccine is the vaccine of choice if recipients are likely to be susceptible to measles and/or rubella as well as to mumps 1 Testing for IgG provides clarity on the patient's true immunity status and prevents unnecessary vaccination in those already protected. This approach aligns with evidence-based practice for determining the need for mumps vaccination in adults with uncertain immunity status.
From the Research
Mumps Vaccine and IgG Antibody Testing
- A patient with low Immunoglobulin M (IgM) antibody levels may benefit from receiving the mumps vaccine or undergoing testing for Immunoglobulin G (IgG) mumps antibody, as studies have shown that a third dose of the measles-mumps-rubella (MMR) vaccine can provide additional protection against mumps virus infection 2, 3, 4, 5.
- Research has demonstrated that a third dose of the MMR vaccine can increase antibody levels and provide long-lasting seroprotection against measles, mumps, and rubella 2, 4, 5.
- Testing for IgG mumps antibody can help identify individuals who may not have developed adequate immunity after initial vaccination, and a third dose of the MMR vaccine can be effective in boosting antibody levels in these individuals 3, 5.
- The dynamics of the antibody response after a third dose of the MMR vaccine indicate a slower decline in antibody levels compared to a second dose, suggesting that a third dose can provide longer-lasting protection against mumps virus infection 4.
- The development and use of an endpoint titration assay to characterize mumps IgG avidity can help determine the effectiveness of the vaccine in inducing long-lasting immunity 6.
Considerations for Vaccine Administration and Testing
- The decision to administer the mumps vaccine or conduct IgG antibody testing should be based on individual factors, such as the patient's vaccination history, antibody levels, and risk of exposure to mumps virus 2, 3, 5.
- A third dose of the MMR vaccine has been shown to be safe and effective in increasing antibody levels and providing protection against mumps virus infection 2, 4, 5.
- The results of IgG antibody testing can inform the decision to administer a third dose of the MMR vaccine, as individuals with low antibody levels may benefit from an additional dose 3, 5.