Prevalence and genotype distribution of norovirus and rotavirus among children under five with diarrheal infection in lower-middle-income countries after Rotavirus vaccine introduction: A systematic review and meta-analysis.

backgroundRotavirus and norovirus are the leading viral causes of acute diarrheal disease worldwide. Both viruses encompass multiple genotypes and subgenotypes, and this genetic diversity presents a significant challenge to rotavirus vaccine effectiveness and development. High-quality evidence on the prevalence and circulating genotypes of these enteric viruses among children under five years of age remains limited, particularly following the introduction of rotavirus vaccination in low and middle-income countries (LMICs). Therefore, this systematic review and meta-analysis aimed to synthesizes available evidence on the prevalence and genotype distribution of norovirus and rotavirus in this population.

methodsA systematic literature search was conducted across five major databases PubMed, Scopus, ScienceDirect, Embase, and Web of Science between February 20 and 28, 2026. Duplicate removal, title and abstract screening, full-text review and data extraction were performed independently by two investigators using the Rayyan web-based platform. STATA version 17 software was used for statistical analysis. A random-effects model was applied to estimate pooled prevalence and effect sizes. Heterogeneity was evaluated using Cochran's Q statistic, the I2 statistic, forest plots, and Galbraith plots. Publication bias was assessed using both graphical (funnel plots) and statistical methods.

resultsA total of 35,704 children under five years with diarrheal infection from LMICs were included across eligible studies. The overall pooled prevalence of norovirus and rotavirus combined was 18% (95% CI: 15-21%). Rotavirus had a higher pooled prevalence than norovirus, at 24% (95% CI: 19.6-28.3%) and 13% (95% CI: 11-15%), respectively. Substantial heterogeneity was observed across studies (I2 = 98.72%, p < 0.001). Among norovirus genotypes, GII was predominant (76%), with subgenotype GII.4 accounting for 53% of cases, followed by GI (23%). The most frequently identified rotavirus genotypes were G3[P8] (39%) and G1[P8] (17%).

conclusionsNorovirus and rotavirus remain significant causes of diarrheal disease among children under five in LMICs, even after the introduction of rotavirus vaccination. Approximately one in five children with diarrheal illness were infected with at least one of these virusesGII, particularly subgenotype GII.4, was the dominant norovirus strain, while G3[P8] and G1[P8] were the most prevalent rotavirus genotypes. These findings underscore the need to strengthen surveillance systems, consider circulating genotypes in vaccine formulation, and continuously monitor genotype shifts within the population.