Seroprotection Against Mumps in MMR Vaccinated Children Aged 9-12 Years: A Cross-Sectional Study

To estimate the proportion of children aged 9-12 years with seroprotective antibody titers against mumps following a single dose of measles-mumps-rubella (MMR) vaccine administered in early childhood, and to explore the association between seroprotection and clinicodemographic profile.

A cross-sectional study was conducted at a tertiary hospital in Delhi between April 2024 and August 2025. Children aged 9-12 years with a documented receipt of a single dose of MMR vaccine at 16-24 months of age were recruited. Two mL of venous blood was collected and analyzed for serum mumps-specific IgG antibodies using enzyme-linked immunosorbent assay (ELISA), with seroprotection defined as mumps antibody titers ≥ 22 RU/mL. The association between seroprotection and demographic and clinical variables, including age, sex, age at vaccination, and nutritional status, was assessed using the chi-square test or Fisher's exact test.

Eighty-six children (48% males) aged 9-12 years [mean (SD) 10.35 (1.04) years] were enrolled. Overall, 84.8% demonstrated seroprotective antibody titers against mumps. The median (q1, q3) mumps-specific IgG titer was 97.6 (46.1, 144.9) RU/mL. Children aged > 10 years were significantly more likely to be seronegative compared to younger children (OR 3.99, 95% CI 1.07, 14.92, P = 0.039).

Nearly 85% of children who had received a single MMR dose at 16-24 months of age had seroprotective mumps antibody titers at 9-12 years. The findings highlight the need for larger community-based studies on the durability of mumps immunity and add to the accumulating evidence informing future MMR vaccination strategies in India.