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

Background India did phased measles-rubella supplementary immunisation activities (MR-SIAs; ie, mass-immunisation campaigns) targeting children aged 9 months to less than 15 years. We estimated measles-rubella seroprevalence before and after the MR-SIAs to quantify the effect on population immunity and identify remaining immunity gaps. Methods Between March 9, 2018 and March 19, 2020 we did community-based, cross-sectional serosurveys in four districts in India before and after MR-SIAs. 30 villages or wards were selected within each district, and one census enumeration block from each was selected as the survey cluster. Households were enumerated and 13 children in the younger age group (9 months to < 5 years) and 13 children in the older ager group (5 to < 15 years) were randomly selected by use of computer-generated random numbers. Serum samples were tested for IgG antibodies to measles and rubella viruses by enzyme immunoassay. Findings Specimens were collected from 2570 children before the MR-SIA and from 2619 children afterwards. The weighted MR-SIA coverage ranged from 73middot7% to 90middot5% in younger children and from 73middot6% to 93middot6% in older children. Before the MR-SIA, district-level measles seroprevalence was between 80middot7% and 88middot5% among younger children in all districts, and between 63middot4% and 84middot5% among older children. After the MR-SIA, measles seroprevalence among younger children increased to more than 90% (range 91middot5 to 96middot0) in all districts except Kanpur Nagar, in which it remained unchanged 80middot4%. Among older children, measles seroprevalence increased to more than 90middot0% (range 93middot7% to 96middot5%) in all districts except Hoshiarpur (88middot7%). A significant increase in rubella seroprevalence was observed in all districts in both age groups, with the largest effect in Dibrugarh, where rubella seroprevalence increased from 10middot6% to 96middot5% among younger children. Interpretation Measles-rubella seroprevalence increased substantially after the MR-SIAs but the serosurvey also identified remaining gaps in population immunity. Copyright (C) 2022 The Author(s). Published by Elsevier Ltd.