Ye L X, Wang H B, Lu H C, Chen B B, Zhu Y Y, Gu S H, Wang J M, Pan X X, Fang T, Dong H J
Ningbo Prefectural Center for Disease Control and Prevention, Ningbo 315010, China.
Ningbo Haishu Distract Center for Disease Control and Prevention, Ningbo 315010.
Zhonghua Liu Xing Bing Xue Za Zhi. 2020 Dec 10;41(12):2029-2033. doi: 10.3760/cma.j.cn112338-20200316-00362.
To investigate a cluster epidemic of COVID-19 after a mass gathering activity in Ningbo of Zhejiang province and analyze the transmission chain and status of infection cases of different generations. The tracking of all the close contacts of the first COVID-19 case and epidemiological investigation were conducted on January 29, 2020 after a cluster epidemic of COVID-19 related with a Buddhism rally on January 19 (the 1.19 rally) in Ningbo occurred. The swabs of nose/throat of the cases and close contacts were collected and tested for nucleic acids by real-time fluorescence quantitative RT-PCR. From January 26 to February 20, 2020, a total of 67 COVID-19 cases and 15 asymptomatic infection cases related with the 1.19 rally were reported in Ningbo. The initial case was the infection source who infected 29 second generation cases and 4 asymptomatic infection cases, in whom 23 second generation cases and 3 asymptomatic infection cases once took bus with the initial case, the attack rate was 33.82% (23/68) and the infection rate was 38.24% (26/68). The risks of suffering from COVID-19 and being infected were 28.91 times and 26.01 times higher in rally participants taking bus with initial case compared with those taking no bus with initial case. In this epidemic, 37 third+generation cases and 11 related asymptomatic infection cases occurred, the attack rate was 2.88% (37/1 283) and the infection rate was 4.76% (48/1 008). The main transmission routes included vehicle sharing and family transmission. It was a cluster epidemic of COVID-19 caused by a super spreader in a massive rally. The epidemic has been under effective control.
为调查浙江省宁波市一次群体性聚集活动后新型冠状病毒肺炎（COVID-19）聚集性疫情，分析传播链条及各代感染病例情况。2020年1月19日宁波发生与一场佛教集会（“1·19集会”）相关的COVID-19聚集性疫情后，于1月29日对首例COVID-19病例的所有密切接触者进行追踪及流行病学调查。采集病例及密切接触者的鼻/咽拭子，采用实时荧光定量RT-PCR检测核酸。2020年1月26日至2月20日，宁波共报告与“1·19集会”相关的COVID-19病例67例、无症状感染者15例。首例病例为传染源，感染了29例二代病例和4例无症状感染者，其中23例二代病例和3例无症状感染者曾与首例病例同乘一辆公交车，罹患率为33.82%（23/68），感染率为38.24%（26/68）。与未与首例病例同乘公交车的集会参与者相比，与首例病例同乘公交车的集会参与者感染COVID-19的风险高28.91倍，被感染的风险高26.01倍。本次疫情中，发生37例三代及以上病例和11例相关无症状感染者，罹患率为2.88%（37/1283），感染率为4.76%（48/1008）。主要传播途径包括共同乘车和家庭传播。这是一起由超级传播者在大规模集会中引发的COVID-19聚集性疫情。疫情已得到有效控制。
