Evaluating the effect of measles and rubella mass vaccination campaigns on seroprevalence in India: a before-and-after cross-sectional household serosurvey in four districts, 2018 - 2020

India conducted phased measles–rubella supplementary immunisation activities (MR-SIAs) targeting children aged 9 months to less than 15 years. Between March 9, 2018 and March 19, 2020, community-based cross-sectional serosurveys were conducted before and after MR-SIAs in four districts. Serum samples from 2570 children before and 2619 after the MR-SIAs were tested for measles and rubella IgG antibodies. MR-SIA coverage ranged from 73·6% to 93·6%. Measles seroprevalence increased substantially after the MR-SIAs, exceeding 90% in most districts and age groups, while rubella seroprevalence increased significantly in all districts, with the largest increase in Dibrugarh. The study found that MR-SIAs substantially increased measles–rubella seroprevalence but also identified remaining gaps in population immunity.