Sustained Efficacy of the Pentavalent Rotavirus Vaccine, RV5, up to 3.1 Years Following the Last Dose of Vaccine

Background: Rotavirus gastroenteritis (RVGE) is a common cause of childhood hospitalizations and emergency department (ED) visits. In the Rotavirus Efficacy and Safety Trial (REST), the pentavalent rotavirus vaccine (RV5) significantly reduced RVGE-associated hospitalizations and ED visits for up to 2 years following the last vaccine dose. This study evaluated whether RV5 remained efficacious beyond 2 years. Methods: A total of 20,736 infants from Finland, initially in REST, were followed for RVGE-associated hospitalizations and ED visits in a Finnish extension study (FES) for up to 3.1 years after vaccination (age, similar to 3.5 years). Results: The FES added >18,500 person-years and captured 150 RVGE-associated hospitalizations and ED visits (11 RV5; 139 placebo). In REST + FES, RV5 reduced RVGE-associated hospitalizations and ED visits, regardless of rotavirus serotype, by 94.0% (95% confidence interval [CI] : 91.4%-95.9%) for up to 3.1 years after vaccination. RV5 also conferred significant protection against hospitalizations and ED visits associated with rotavirus serotypes G1 (95.5%; 95% CI: 92.8%-97.2%), G2 (81.9%; 95% CI: 16.1%-98.0%), G3 (89.0%; 95% CI: 53.3%-98.7%), G4 (83.4%; 95% CI: 51.2%-95.8%), and G9 (94.2%; 95% CI: 62.2%-99.9%). Rate reductions (95% CI) in hospitalizations and ED visits during the first, second, and third years of life were 94.0% (90.0%-96.5%), 94.7% (90.7%-97.2%), and 85.9% (51.6%-97.2%), respectively. Conclusions: RVGE-associated hospitalizations and ED visits remain common in the second year of life but decrease in the third year of life. RV5 showed sustained protective efficacy against RVGE-associated hospitalizations and ED visits, regardless of rotavirus serotype, for up to 3.1 years after vaccination.