Outbreak investigation of SARS-CoV-2 transmission in an emergency childcare centre

• Published in: Canadian journal of public health Vol. 112; no. 4; pp. 566 - 575
• Main Authors: Soto, Julio C., Barakat, Mireille, Hutter, Juliana Ayres, Kiely, Marilou, Moreira, Sandrine, Shapiro, B. Jesse, Murall, Carmen Lia, Parenteau, Nicolas, Désilets, Joane, Lessard, Richard
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-08-2021; Springer Nature B.V
• Subjects: Asymptomatic; Child care; Children; Children & youth; Coronaviruses; COVID-19; Daycare; Disease transmission; Epidemiology; Gene sequencing; Genomes; Long-term care; Medicine; Medicine & Public Health; Outbreaks; Phylogenetics; Phylogeny; Polymerase chain reaction; Population studies; Public Health; Severe acute respiratory syndrome; Severe acute respiratory syndrome coronavirus 2; Social networks; Social organization; Special Section on COVID-19: Quantitative Research; Viral diseases; Whole genome sequencing; Canada; Transmission; Daycare; éclosion; école; analyse phylogénétique; COVID-19; Phylogenetic analysis; SARS-CoV-2; School; Outbreak; Children; garderie; enfants
• ISSN: 0008-4263; 1920-7476
• DOI: 10.17269/s41997-021-00544-1

Objective
To characterize SARS-CoV-2 transmission following a COVID-19 outbreak in an emergency childcare centre (ECCC) in April 2020 in Quebec, Canada.
Methods
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.
Results
Phylogenetic analysis identified two separate introductions of distinct lineages of SARS-CoV-2 and estimated an average effective reproductive number of
R
e
= 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.
Conclusion
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.