AbstractIt is proposed that measles‐containing vaccines have immunomodulatory effects which include a reduction in all‐cause childhood mortality. The antibody response to heterologous vaccines provides a means to explore these immunomodulatory effects. This is the first study to investigate the influence of measles‐mumps‐rubella (MMR) vaccine on the persistence of antibodies to a broad range of heterologous infant vaccinations given in the first year of life. In total, 319 children were included in the study. All infants received routine vaccinations at 6 weeks, 4 and 6 months of age. At 12 months of age, 212 children were vaccinated with MMR and Haemophilus influenzae type b‐meningococcus C (Hib‐MenC) vaccines while the remaining 99 children had not yet received these vaccines. In the MMR/Hib‐MenC‐vaccinated group, blood was taken 28 ± 14 days after receiving these vaccines. Antibodies against diphtheria, tetanus, pertussis [pertussis toxin (PT), filamentous hemagglutinin, pertactin], poliomyelitis (type 1, 2, 3) and 13 pneumococcal serotypes were measured. Seroprotection rates and geometric mean antibody concentrations were compared between MMR/MenC‐Hib‐vaccinated and MMR/MenC‐Hib‐naïve participants. In the final analysis, 311 children were included. Seroprotection rates were lower in MMR/Hib‐MenC‐vaccinated children against PT and pneumococcal serotype 19A. After adjustment for prespecified factors, MMR/Hib‐MenC‐vaccinated infants had significantly higher antibody concentrations against tetanus (likely explained by a boosting effect of the carrier protein, a tetanus toxoid), while for the other vaccine antigens there was no difference in antibody concentrations between the two groups. MMR vaccination given at 12 months of age in a developed country does not significantly influence antibody concentrations to heterologous vaccines received in the first year of life.