Direction des risques biologiques et de la santé au travail, Institut national de santé publique du Québec, 190 boul. Crémazie Est, Montréal, Québec, H2P 1E2, Canada.
Laboratoire de santé publique du Québec, Institut national de santé publique du Québec, Montréal, Québec, Canada.
Can J Public Health. 2021 Aug;112(4):566-575. doi: 10.17269/s41997-021-00544-1. Epub 2021 May 28.
To characterize SARS-CoV-2 transmission following a COVID-19 outbreak in an emergency childcare centre (ECCC) in April 2020 in Quebec, Canada.
The study population consisted of all the children and employees who attended the ECCC as well as household contacts of the confirmed COVID-19 cases. Of the 120 individuals in the study, five cases were confirmed by epidemiological link and 25 were identified as COVID-19 by RT-PCR among which 19 were analyzed by viral whole genome sequencing. Descriptive epidemiology, social network visualization, and phylogenetic analysis were used to characterize viral transmission.
Phylogenetic analysis identified two separate introductions of distinct lineages of SARS-CoV-2 and estimated an average effective reproductive number of R = 1.9 (range 0.9-4.9) with a mean doubling time of 3.2 days (range 2.1-5.2). The first and most prevalent lineage was introduced by two asymptomatic children who were likely infected by their parent, a confirmed COVID-19 case working in a long-term care centre. Among infected household adults, attack rates were significantly higher in mothers than in fathers (risk ratio = 4.5; 95% CI 1.1-18.7). The extent of transmission makes it one of the largest documented outbreaks in a daycare in Canada.
The analyses carried out showed the probable origin and direction of the transmission of the infection (adult-child, child-adult, and child-child), thus highlighting how asymptomatic children can efficiently transmit SARS-CoV-2.
描述 2020 年 4 月加拿大魁北克省一家新冠肺炎疫情应急托儿所（ECCC）发生的 SARS-CoV-2 传播情况。
研究人群包括所有入托的儿童和工作人员，以及确诊新冠肺炎病例的家庭接触者。在 120 名研究对象中，5 例通过流行病学关联确诊，25 例通过 RT-PCR 确定为 COVID-19，其中 19 例通过病毒全基因组测序进行分析。采用描述性流行病学、社交网络可视化和系统发育分析方法来描述病毒传播情况。
系统发育分析确定了 SARS-CoV-2 两个不同谱系的两次独立传入，并估计平均有效繁殖数 R=1.9（范围 0.9-4.9），平均倍增时间为 3.2 天（范围 2.1-5.2）。第一个也是最常见的谱系是由两名无症状儿童传入的，他们可能是被在长期护理中心工作的确诊新冠肺炎病例的父母感染的。在感染的家庭成人中，母亲的发病风险明显高于父亲（风险比=4.5；95%CI 1.1-18.7）。传播的程度使其成为加拿大日托所记录的最大规模暴发之一。
进行的分析表明了感染传播的可能来源和方向（成人-儿童、儿童-成人和儿童-儿童），从而突出了无症状儿童如何有效传播 SARS-CoV-2。
