Objective To analyze prevalence and genetic characteristics of clusterings/outbreaks of norovirus (NV) infection in Guangdong province in 2021.
Methods We collected the information on all laboratory confirmed NV infection clusterings (3 correlated cases in 3 days at a venue) and outbreaks (20 correlated cases in 7 days at a venue) reported in Guangdong province throughout 2021. Anal swab/stool specimens of the reported cases were sampled for NV detection with quantitative real-time PCR (qRT-PCR). The NV GI and GII strains screened out from positive specimens were genotyped with PCR amplification, library preparation, gene sequencing and splicing.
Results Of a total of 141 NV clusterings/outbreaks reported in the province during the year, 92.91% occurred in nurseries or schools and mainly during winter and spring seasons. For the genotyped NV strains isolated from specimens of 73 outbreaks (51.77% of all epidemics), 94.52% were NV GII, with GII.2P16 and GII.4P31 accounting for 39.13% and 23.19% of all NV strains, respectively.
Conclusion In Guangdong province during 2021, the norovirus clusterings/outbreaks occurred mainly in nurseries and schools in winter/spring seasons and the majority of the outbreaks were caused by norovirus GII.2P16 and GII.4P31.
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