Methods : We did a systematic review of published work to assess the strain-specific effectiveness of RV1 and RV5 rotavirus vaccines. We classified strains as homotypic, partly heterotypic, and fully heterotypic based on the amount of antigen-matching between strain and vaccine. When studies reported vaccine effectiveness against single antigens (G-type or P-type), we categorised them as either single-antigen vaccine type or single-antigen non-vaccine type. Our primary outcome was strain-specific vaccine effectiveness, comparing effectiveness of homotypic strains with fully or partly heterotypic strains. A secondary outcome was the prevalence of rotavirus strains after vaccine introduction. We estimated pooled odds ratios using random-effect regression models, stratified by country income level and vaccine type, and tested for differences in strain-specific vaccine effectiveness. We assessed strain distribution trends from surveillance reports.
Findings : In high-income countries, RV1 pooled vaccine effectiveness was 94% (95% CI 80—98) against homotypic strains, 71% (39—86) against partly heterotypic strains, and 87% (76—93) against fully heterotypic strains. In middle-income settings, respective pooled data were 59% (36—73), 72% (58—81), and 47% (28—61). In high-income countries, RV5 vaccine effectiveness was 83% (78—87) against homotypic strains, 82% (70—89) against single-antigen vaccine type strains, 82% (70—89) against partly heterotypic strains, and 75% (47—88) against single-antigen non-vaccine type strains. In middle-income settings, RV5 vaccine effectiveness was 70% (58—78) against single-antigen vaccine type strains, 37% (10—56) against partly heterotypic strains, and 87% (38—97) against single-antigen non-vaccine type strains. No difference was noted in vaccine effectiveness for either RV1 or RV5 in any setting (all p>0·05). Prevalent strains in countries using RV1 were G2P (2198 of 4428, 50%) and G1P (953, 22%), and those in countries using RV5 were G1P (1280 of 3875, 33%) and G2P (1169, 30%). Sustained predominance of a single strain was not recorded.
Interpretation : RV1 and RV5 exert similar effectiveness against homotypic and heterotypic rotavirus strains. Persistence of specific strains was not recorded, suggesting vaccine-induced selective pressure did not occur. Expansion of rotavirus surveillance efforts to low-income countries and ongoing surveillance are crucial to identify emergence of new strains and to assess strain-specific vaccine effectiveness in various settings (read more)