Abstract / Summary
Norovirus is a leading cause of acute gastroenteritis (AGE) worldwide, with significant morbidity and mortality, particularly in young children and older adults. This study characterizes the global prevalence and diversity of norovirus genotypes among sporadic cases. A review of English-language studies (published 2002–2026) that characterized norovirus genotype distribution among sporadic cases was conducted, excluding outbreak and asymptomatic detections. Pooled data were analyzed with stratifications by age group, region, and year of sample collection. A total of 20,588 cases were identified from 72 publications. There were 30 genotypes identified, with GII.4, GII.3, GII.2, GII.17, and GII.6 and each accounting for ≥5% of detections. GII.4 was the predominant genotype globally, accounting for 54% of cases and up to 80% among older adults across all years, but periodic fluctuation was seen, coinciding with fluctuations in the prevalence of other genotypes, especially GII.3, GII.2, and GII.17. Among GI genotypes, GI.3 was most prevalent (46%), particularly among adults. Genotype diversity was highest among children in low- and middle-income countries and in Asia/Oceania. Findings indicate that a small number of genotypes account for most cases. As genotyping characterizes the major capsid protein, the primary target of antibody recognition, findings have important implications for vaccine development and public health interventions.