Effectiveness of an Indigenous Pentavalent, Live Attenuated, Oral Rotavirus Vaccine ROTASIIL® among Children Younger than 2 Years of Age Hospitalized with Acute Gastroenteritis in Seven States of India: 2019-2023

ROTASIIL®, a pentavalent oral rotavirus vaccine licensed in India in 2017, was introduced into the Universal Immunization Programme in 2018. We assessed vaccine effectiveness (VE) against moderate-to-severe rotavirus gastroenteritis (RVGE) in children < 2 years using pooled data from two multi-centric observational studies across 32 hospitals in seven states (July 2019–December 2023). A test-negative case–control design estimated adjusted VE (aVE) for three ROTASIIL® doses. Among 2,243 children aged 4–23 months hospitalized with acute gastroenteritis, 638 were ELISA-positive. Overall aVE was 52% (95% CI, 32–66), highest in < 6 months was 88%, (CI, 53–97). The aVE against severe and moderate RVGE was 54% (CI, 31–70) and 56% (CI, 11–79), respectively and for at least one dose was 45% (CI, 26–60). Highest genotype-specific aVE was 62% (CI, 29–80) against G1P[8]. A completed series of ROTASIIL® effectively reduced RVGE hospitalizations; protection waned with age, suggesting benefits of timely immunization.