Evaluation of cellular immunity to mumps in vaccinated individuals with or without circulating antibodies up to 16 years after their last vaccination.

In this observational study, mumps-specific in vitro lymphoproliferation was measured in 24 subjects with low antibody titers and 24 subjects with high antibody titers who received their last vaccine dose up to 16 years previously. Overall, a significant lymphoproliferative response was found in 32 subjects (66.7%)-namely, in 13 (54.2%) of those with low antibody titers and 19 (79.2%) of those with high antibody titers. The mean stimulation index for subjects with low antibody titers was 4.47, whereas that for subjects with high antibody titers was 8.31 (P = .032). Mumps vaccine-induced cell-mediated immunity appears to be more persistent than the antibody response.