How long after Measles, Mumps, and Rubella (MMR) vaccine should titers show immunity?

MMR Vaccine Titers: Timeline for Immunity Detection

Antibody titers should show immunity 6 weeks after MMR vaccination, with most individuals developing detectable antibodies by this timepoint. 1

Immune Response Timeline

The development of immunity after MMR vaccination follows a predictable pattern:

• Initial response: Vaccine virus replication and stimulation of immunity typically occurs 1-2 weeks after vaccination 2
• Peak antibody development: Clinical studies show that 6 weeks post-vaccination is the standard timepoint for measuring seroconversion 1
• Seroconversion rates at 6 weeks:
  • Measles: 94-96% of individuals develop antibodies
  • Mumps: 96-98% of individuals develop antibodies
  • Rubella: 98-99% of individuals develop antibodies 1

Component-Specific Considerations

Measles

• Measles HI (hemagglutination-inhibition) antibodies develop in approximately 95% of susceptible individuals by 6 weeks 1
• Seroresponse threshold is defined as ≥255 mIU/mL 1

Mumps

• Mumps neutralizing antibodies develop in approximately 96% of susceptible individuals by 6 weeks 1
• Seroresponse threshold is defined as ≥10 EU/mL 1

Rubella

• Rubella HI antibodies develop in approximately 99% of susceptible individuals by 6 weeks 1
• Seroresponse threshold is defined as ≥10 IU/mL 1

Factors Affecting Antibody Response

Several factors can influence the development of detectable antibodies after MMR vaccination:

• Recent administration of immune globulins: High doses of immune globulins can inhibit the immune response to measles and rubella vaccine for 3 or more months 2
• Immunocompromised status: Severely immunocompromised individuals may have suboptimal antibody responses 2
• Age at vaccination: Children vaccinated at 15 months generally have higher antibody titers than those vaccinated at 9 months, particularly for rubella 3

Clinical Implications

• If titers are checked before 6 weeks post-vaccination, false negative results may occur as antibody development is still in progress
• For individuals who do not seroconvert after the first dose, a second dose of MMR is recommended, which results in significantly higher seroconversion rates:
  • After a second dose, seropositivity rates increase to 99.6% for measles (compared to 85.7% after first dose) 2
  • GMTs (geometric mean titers) are substantially higher after a second dose (142 vs. 12 after first dose) 2

Long-term Persistence of Antibodies

After vaccination, neutralizing and ELISA antibodies remain detectable for many years:

• Measles: 95-100% of individuals maintain detectable antibodies 11-13 years after primary vaccination
• Mumps: 74-91% of individuals maintain detectable antibodies 11-13 years after primary vaccination
• Rubella: 90-100% of individuals maintain detectable antibodies 11-13 years after primary vaccination 1

In conclusion, when checking for immunity after MMR vaccination, testing should be performed no earlier than 6 weeks post-vaccination to ensure accurate assessment of the immune response.