Background: The 2-dose, oral live attenuated human G1P rotavirus vaccine (RIX4414) is highly effective against rotavirus gastroenteritis caused by circulating G1 and non-G1 types. An integrated analysis on vaccine efficacy was undertaken to obtain more precise estimates of the overall protective effect of the RIX4414 vaccine against rotavirus gastroenteritis due to common rotavirus types (G1, G3, G4, G9, P) and less commonly encountered strains such as G2P across heterogenous settings.
Methods: The studies used in the integrated analysis were all previously reported randomized, double-blind, placebo-controlled, phase II and III trials with at least 1 report of rotavirus gastroenteritis in the efficacy follow-up period (up to 1 year of age or end of first RV epidemic season after vaccination). The integrated analysis was performed for all circulating rotavirus strains sharing G and/or P genotype and not sharing G or P genotype with the vaccine strain. Vaccine efficacy was estimated as 1 minus rate of rotavirus gastroenteritis relative to placebo, using exact Poisson rate ratio stratified by study.
Results: The integrated estimates for vaccine efficacy against severe rotavirus gastroenteritis were 87.43% (95% confidence interval [CI]: 78.89–92.86) for G1P strains, 71.42% (95% CI: 20.12–91.11) for G2P strains, 90.19% (95% CI: 55.51–98.94) for G3P strains, 93.37% (95% CI: 51.50–99.85) for G4P strains, and 83.76% (95% CI: 71.18–91.28) for G9P strains. The integrated estimates for vaccine efficacies against rotavirus gastroenteritis of any severity were 82.57% (95% CI: 73.91–88.56) for G1P strains, 81.04% (95% CI: 31.58–95.76) for G2P strains, 87.66% (95% CI: 34.57–98.76) for G3P strains, 84.86% (95% CI: 50.92–96.41) for G4P strains, and 60.64% (95% CI: 38.15–74.96) for G9P strains.
Conclusions: Two doses of RIX4414 provide overall good clinical protection against all cases of rotavirus gastroenteritis and comparable, high clinical protection against severe rotavirus gastroenteritis caused by circulating rotavirus strains with and without G and P genotypes shared with the vaccine strain, such as G2P.