Molecular epidemiological characteristics of norovirus outbreaks reported to Chinese norovirus outbreak laboratory surveillance network, 2016–2019

  Objective  To understand the development of Chinese norovirus outbreak surveillance network (CaliciNet China) and the molecular epidemiological characteristics of norovirus outbreak reported to CaliciNet China from 2016 to 2019.

  Methods  The epidemiological and clinical information of norovirus outbreaks in China from October 2016 to September 2019 were collected by the network laboratories of CaliciNet China. Real-time RT-PCR was used to detect norovirus. The positive samples were amplified by genotyping RT-PCR and sequenced. The data were entered into the CaliciNet China database for analysis.

  Results  From October 2016 to September 2019, a total of 1153 norovirus outbreaks were reported, and the positive samples of 776 outbreaks (67.3%) were genotyped. Most of these outbreaks (94.9%) were related to human-to-human transmission and occurred in child care settings or schools (94.4%). Norovirus outbreaks mainly occurred from November to March every year (65.0%). During the three-year study period, 57.6% of the outbreaks were caused by norovirus GⅡ.2［P16］.

  Conclusion  GⅡ.2［P16］ was the main genotype of norovirus causing outbreaks, mainly in child care settings or schools, in China from October 2016 to September 2019. The ongoing surveillance by CaliciNet China provides information on the genotypes of norovirus strains and molecular characteristics of norovirus outbreaks, which is very important for development of effective intervention measures (including vaccination) for norovirus outbreaks