Seroprevalence of mumps and rubella antibodies among Indian children: evidence of a mumps immunity gap.

Mumps and rubella are highly contagious, vaccine-preventable diseases; however, India's National Immunization Program prioritizes rubella while excluding mumps. In this cross-sectional study, we measured mumps- and rubella-specific IgG seroprevalence in 508 children (49.6% female) from Kerala and evaluated demographic associations. Seropositivity was 78.5% (95% CI, 74.8-81.9%) for mumps and 99.4% (95% CI, 98.3-99.8%) for rubella. Mumps IgG titers were significantly higher in females (p = 0.0061) and increased with vaccine doses (p < 0.001), whereas rubella IgG titers showed no such associations (p > 0.05). IgG titers for both mumps (r = -0.13, p = 0.0043) and rubella (r = -0.23, p < 0.001) declined with time since vaccination, indicating waning immunity. The contrast between high rubella and lower mumps immunity likely reflects differences in vaccination prioritization and support the inclusion of mumps-containing vaccines into India's National Immunization Program, ideally through universal adoption of the measles-mumps-rubella (MMR) vaccine.