Norovirus is a leading cause of acute gastroenteritis (AGE) globally. AGE resulting from norovirus causes significant morbidity and mortality in countries of all income levels, particularly among young children and older adults. Prevention of norovirus AGE represents a unique challenge as the virus is genetically diverse with multiple genogroups and genotypes cocirculating globally and causing disease in humans. Variants of the GII.4 genotype are typically the most common genotype, and other genotypes cause varying amounts of disease year-to-year, with GII.2, GII.3, and GII.6 most prevalent in recent years. Noroviruses are primarily transmitted via the fecal-oral route and only a very small number of virions are required for infection, which makes outbreaks of norovirus extremely difficult to control when they occur. Settings like long-term care facilities, daycares, and hospitals are at high risk of outbreaks and can have very high attack rates resulting in substantial costs and disease burden. Severe cases of norovirus AGE are most common in vulnerable patient populations, such as infants, the elderly, and immunocompromised individuals, with available treatments limited to rehydration therapies and supportive care. To date, there are no FDA-approved norovirus vaccines; however, several candidates are currently in development. Given the substantial human and economic burden associated with norovirus AGE, a vaccine to prevent morbidity and mortality and protect vulnerable populations could have a significant impact on global public health.

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.

Noroviruses pose a major public health challenge in structurally closed or semi-closed settings where person-to-person contact, shared environment, and high-risk populations facilitate rapid transmission. This narrative review synthesizes epidemiological evidence on the burden of norovirus infection in closed and semi-closed settings, such as long-term care facilities (LTCFs), healthcare facilities, schools, childcare centers, and cruise ships, where norovirus transmission risk is elevated. Priority populations frequently experiencing high attack rates and patterns of key factors related to norovirus transmission are summarized for each context. Reported attack rates varied substantially both within and across settings, with elevated attack rates reported in LTCFs, healthcare facilities, childcare settings, and several other closed or semi-closed settings. Norovirus outbreaks are frequent and severe in closed and semi-closed settings, highlighting the need for targeted prevention and control measures in these contexts.