What are the recommendations for a patient who has completed the Measles, Mumps, and Rubella (MMR) vaccine series but has a low Mumps antibody Immunoglobulin G (IgG) titer?

Management of Low Mumps Antibody IgG Titers in Patients Who Have Completed MMR Vaccination

For patients who have completed the MMR vaccine series but show low mumps antibody IgG titers, administration of an additional dose of MMR vaccine is recommended to boost immunity. 1, 2

Understanding Mumps Vaccine Failure

• Primary vaccine failure occurs when individuals fail to develop adequate antibody response after vaccination
• Mumps outbreaks have been documented in highly vaccinated populations, with substantial cases occurring among individuals who previously received one or two doses of mumps-containing vaccine 1
• Research shows that:
  • Mumps antibody levels tend to be lower than measles and rubella antibody levels in vaccinated individuals 3
  • Mumps-specific memory B cells are 5-10 times lower than those for measles and rubella 3
  • Approximately 10% of vaccinated young adults have no detectable memory B cells to mumps 3
  • Neutralizing antibody titers against circulating wild-type mumps strains can be 6-fold lower than against the vaccine strain 3

Recommended Approach

1. Administer an additional (third) dose of MMR vaccine

   • This is the simplest and safest approach for individuals with low mumps antibody titers 1
   • No evidence indicates increased risk of adverse reactions among persons already immune to mumps 1
   • A third dose can provide a modest but statistically significant increase in mumps antibody levels 2

2. Timing considerations:

   • Administer immediately, as delaying intervention can reduce effectiveness 4
   • The additional dose should be given subcutaneously in the standard single-dose volume of 0.5 mL 1

3. Expected outcomes:

   • Individuals with the lowest baseline neutralizing antibody titers show the largest increase in antibody response after an additional dose 2
   • Antibody levels typically peak at 1 month post-vaccination and remain elevated above baseline at 1 year 2
   • The additional dose is particularly beneficial in high-risk settings or during outbreaks 2

Special Considerations

• Healthcare workers: Those with low mumps antibody titers should receive an additional MMR dose, especially given their higher risk of exposure and potential to transmit infection 4

• Immunocompromised patients: Severely immunocompromised individuals should NOT receive MMR vaccine regardless of antibody status and should instead receive immune globulin prophylaxis if exposed to mumps 1, 4

• Pregnancy: MMR vaccine is contraindicated during pregnancy 4

Common Pitfalls to Avoid

1. Misinterpreting serologic test results:

   • Poor correlation exists between different serologic tests for mumps antibodies 2
   • Commercial ELISA results may not accurately predict neutralizing antibody levels 2

2. Delaying intervention:

   • Do not delay administration of the additional MMR dose while awaiting further serologic testing 4

3. Assuming long-term protection:

   • Mumps antibody levels may decline over time even after multiple doses 5
   • Unlike measles and rubella, mumps immunity appears to wane more significantly 5, 6

By providing an additional dose of MMR vaccine to patients with low mumps antibody titers, you can help boost their immunity and reduce their risk of mumps infection, particularly in outbreak settings or high-risk environments.