Norovirus outbreaks in Beijing, China, from 2014 to 2017.

Objectives: Noroviruses are a leading cause of acute gastroenteritis (AGE) outbreaks worldwide. This study examined the epidemiology and genetic characteristics of norovirus outbreaks in Beijing, China.

Methods: Epidemiological data and fecal specimens were collected through the AGE outbreak surveillance system in Beijing. GI and GII genogroup noroviruses were detected and genotyped. The data were analyzed using descriptive statistics.

Results: Between September 2014 and August 2017, 762 AGE outbreaks were reported in Beijing, of which 661 (86.7%) were laboratory-confirmed as norovirus. Most norovirus outbreaks were reported during the spring (66.9%, 442/661), occurred in kindergartens and elementary schools (92.3%, 610/661), and were caused by GII genogroup noroviruses (95.6%; 632/661). The genotypes of the norovirus strains were determined in 468 outbreaks, and GII.P16-GII.2 and GII.P17-GII.17 strains were the most commonly identified. GII.P17-GII.17 and GII.P16-GII.2 strains predominated in 2014-2015 and 2016-2017 outbreaks, respectively. GII.P16-GII.2 noroviruses were responsible for a steep increase in AGE outbreaks in Beijing: 549 norovirus outbreaks were reported from 2016 to 2017, 9.2 times the number that occurred during the previous year.

Conclusions: Norovirus causes a large disease burden in Beijing, and the prevalence of non-GII.4 noroviruses presents a new challenge for the development of vaccines.