Effectiveness of the oral rotavirus vaccine ROTASIIL among children hospitalized with acute gastroenteritis in India.

ROTASIIL®, a pentavalent oral rotavirus vaccine licensed in India in 2017, was introduced into the Universal Immunization Program in 2018. Primary endpoint was vaccine effectiveness (VE) against moderate and severe rotavirus gastroenteritis (RVGE) in children <2 years using pooled data from two multi-center 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 3-23 months hospitalized with acute gastroenteritis, 638 were ELISA-positive. For completed series (three doses), the aVE against hospitalization due to RVGE among children aged 3-23 months was 52% (95% CI, 32-66), with the highest aVE of 88% (CI, 53-97) observed among those aged 3-5 months. The aVE against moderate RVGE was 56% (CI, 11-79), and that of severe RVGE was 54% (CI, 31-70). The highest genotype-specific aVE was 62% (CI, 29-80) against G1P[8]. For at least one dose, the aVE was 45% (CI, 26-60) among children aged 1-23 months. A completed series of ROTASIIL® effectively reduced RVGE hospitalizations especially with a higher VE observed in younger age groups, suggesting the benefits of timely immunization.