Durability of the Mumps Antibody Response After the Third Dose of MMR Vaccine.

Abstract

A third dose of measles, mumps, and rubella vaccine (MMR3) may be administered in outbreak and nonoutbreak settings. However, data on long-term immunogenicity to the mumps component of MMR are limited. We examined durability of mumps antibody response among adults up to 11 years after receipt of MMR3. Persons who received MMR3 at ages 18-28 years had sera collected before (baseline), 1 month, 1, 5, and 9-11 years after vaccination. Mumps antibodies were assessed by plaque reduction neutralization, immunoassay (EIA), and immunoglobulin G (IgG) avidity. Neutralizing antibodies were assessed against the vaccine strain (Genotype A) and a wild-type virus from Genotype G. Participants with neutralizing antibody titers <31 for Genotype A and <8 for Genotype G, and with EIA index values <1.10 were considered potentially susceptible. Among participants with data for all visits after MMR3 (40%, n = 262/655), susceptibility based on Genotype A titers increased from 15.7% (41/262) at baseline to 30.5% (80/262) 9-11 years after vaccination while susceptibility based on Genotype G titers remained relatively stable (30.2%-24.2%). The proportion of participants seronegative for mumps IgG by EIA increased from 0% (0/255) at baseline to 7.5% (19/255) 9-11 years after vaccination. The avidity index increased from 52% to 67% through Year 5 (P < .0001). By 9-11 years after receipt of MMR3, many participants had mumps antibody levels that predicted susceptibility to infection, comparable to those observed before receipt of MMR3. The antibody titers to Genotype G remained consistently lower than the titers to the vaccine strain.