Abstract Background India was among the first Southeast Asian countries to introduce rotavirus vaccines (Rotavac and Rotasiil) into its Universal Immunization Programme (UIP). Both showed efficacy in trials and protection against multiple genotypes, though concerns remain about cross-protection and strain selection. Methods We leveraged multicentric surveillance studies to assess the impact of vaccination on circulating rotavirus strains. From 2016 to 2023, hospital-based diarrheal surveillance enrolled children under five hospitalized with acute watery diarrhea. Stool samples were tested by rotavirus enzyme immunoassay (EIA), and positives were genotyped. Results Among 27,862 samples, 6755 (24·2%) were rotavirus EIA positive, with the highest positivity in eastern and northeastern regions. Positivity declined from 31·2% to 17·5% over the study period, compared to 37% before vaccine rollout. Genotype distribution was broadly consistent across regions, dominated by G3P8 (44·7%), G1P8 (14·7%), G2P4 (14·1%), and G1P6 (4·5%). Mixed infections occurred in 13·9%. G12P8 was frequent in the northeast. Post-vaccine introduction, G3P8 and G2P4 increased while G1P8 declined. Genotype patterns differed by vaccine type: G2P4 was more common at Rotasiil sites (30·9%) than Rotavac sites (10·2%), while mixed infections were lower at Rotasiil sites (7·8%) compared to Rotavac sites (15·3%). Conclusions Rotavirus vaccination significantly reduced disease burden among under-five children in India. G3P8 remained consistently dominant across regions, vaccine types, and years. Regional and vaccine-specific differences were evident, but trends suggest natural viral evolution may outweigh vaccine-driven selection. Sustained surveillance is essential to detect emerging strains and ensure long-term vaccine effectiveness.
Varghese et al. (Sat,) studied this question.