Molecular epidemiology of viral enteric in children in Hangzhou.

BACKGROUND: Viral diarrhea is a major global health burden in children. The implementation of unprecedented non-pharmaceutical interventions (NPIs) during the COVID-19 pandemic, including lockdowns, travel restrictions, school closures, enhanced hand hygiene, and mask-wearing, significantly altered the transmission dynamics of many infectious diseases globally. These measures, primarily targeting respiratory pathogens like SARS-CoV-2, were also anticipated to impact the circulation of enteric viruses, which often spread through the fecal-oral route or via contaminated surfaces and aerosols. However, the extent and nature of this impact on the prevalence, seasonality, and genotype distribution of major pediatric enteric viruses including rotavirus (RV), norovirus (NV), adenovirus (ADV), astrovirus (ASV), and sapovirus (SAV) are key pathogens, their molecular epidemiology during the COVID-19 Pandemic remains poorly characterized. This study aimed to delineate the prevalence, genotype distribution, and genetic features of eight enteric viruses in children with acute diarrhea in Hangzhou, China, from March 2019 to December 2020, encompassing phases before and after COVID-19 emergence. METHODS: A hospital-based cross-sectional study analyzed 1,510 stool samples from children with acute diarrhea. Eight viruses (RVA, RVB, RVC, NV GI/GII, ADV, ASV, SAV) were detected using qRT-PCR. Positive samples underwent targeted gene sequencing followed by phylogenetic analysis and amino acid mutation screening against reference strains. RESULTS: Enteric viruses were detected in 33.38% (504/1,510) of samples. NV GII dominated (48.02%, 242/504), with GII.4 as the predominant genotype (84.62%, 88/104). Temporal shifts were observed: for ASV, HAstV-1 replaced HAstV-5 post-2020, and RV G9 persisted as the dominant genotype (47.06%, 8/17) throughout the study period. ADV 41 remained prevalent (97.37%, 37/38), while SAV exclusively showed GI.1 strains. All amino acid mutations matched known variants. CONCLUSION: This study offers the first molecular epidemiology data on eight enteric viruses in Hangzhou during a period overlapping with COVID-19. The observed genotype shifts, which highlights the need for targeted surveillance.