Objective  To analyze epidemiological characteristics, infection source and transmission route of the first clustering of coronavirus disease 2019 (COVID-19) in Zhuhai city of Guangdong province.

  Methods  We carried out a field survey on 3 laboratory-confirmed cases of COVID-19 in a family and 50 close contacts of the cases on January 20, 2020 in the city.

  Results  The first two cases of the clustering were a couple (the man aged 78 years and the women 76 years) and they had a history of a 5-day traveling in Wuhan city and having a dinner with family members in the city; the two cases had severe symptoms and were admitted into hospitals on January 17, 2020 and were confirmed positive for novel conronavirus nucleic acid the next day. The estimated incubation period was 5 days for the two cases. The third case of the clustering was the couple′s daughter (49 years) with mild symptoms and laboratory confirmation; the third case had histories of a 7-day living together with and taking hospitalization care of the first two cases; the estimated incubation period for the case was less than 6 days. The duration was 30-day and 18-day for the first and second case′s throat and anal swab specimens positive to viral nucleic acid but 5-day for the third case′s throat swab specimens, respectively. No specimens of novel conronavirus nucleic acid positive were detected during the 14 day′s medical observation among the 50 close contacts of the three cases.

  Conclusion  The survey confirms a clustering of COVID-19 and human-to-human transmission the novel coronavirus.