Patterns of Decline in Measles, Mumps, and Rubella Neutralizing Antibodies and Protection Levels Through 10 Years After a Second and Third Dose of MMR Vaccine.

Background: In the United States, 2 doses of measles-mumps-rubella (MMR)-containing vaccines are recommended routinely during childhood; a third dose may be given under certain circumstances. We present observed seroprotection rates and estimate long-term dynamics of measles, mumps, and rubella neutralizing antibody (nAb) levels among 2- and 3-dose MMR (MMR2 and MMR3, respectively) vaccinees. Methods: Persons who received MMR2 at age 4-12 years or MMR3 at age 18-31 years were enrolled in 1994-1995 and 2009-2010, respectively. Per cohort, sera were collected before vaccination (baseline) and at various intervals ranging from 1 month to 10 years postvaccination to assess nAb levels. Annual changes in nAb levels per virus and cohort were estimated through 10 years postvaccination using generalized estimating equations. Models were stratified by baseline nAb levels. Results: Among MMR2 participants (n = 621), 93.7%, 73.4%, and 83.9% had protective nAb levels against measles, mumps, and rubella, respectively, at the 10-year visit; among MMR3 participants (n = 665), 90.5%, 69.1%, and 100% had protective nAb levels, respectively, at the 9-11-year visit. Estimated nAb levels declined annually across both cohorts, all viruses, and baseline nAb strata, though patterns and magnitude varied. More than one-quarter of participants had mumps nAb levels below the presumed seroprotection threshold at the terminal visits. Conclusions: These findings indicate that even when MMR antibodies wane, protection against disease is largely retained. Waning of mumps antibodies was greater than for measles and rubella in both 2- and 3-dose vaccinees, likely because a greater proportion failed to mount a robust initial response.