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Outbreak investigation of SARS-CoV-2 transmission in an emergency childcare centre
Julio C Soto1, Mireille Barakat2, Juliana Ayres Hutter2
1Direction 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. julio.soto@inspq.qc.ca.
Insights
Asymptomatic children efficiently transmit SARS-CoV-2, as shown by a large COVID-19 outbreak in a Canadian emergency childcare centre. This study highlights child-to-adult and child-to-child transmission dynamics.
Area of Science:
- Epidemiology
- Virology
- Public Health
Background:
- COVID-19 outbreaks in childcare settings pose unique transmission challenges.
- Understanding SARS-CoV-2 transmission dynamics in young populations is crucial for public health interventions.
Purpose of the Study:
- To characterize the transmission patterns of SARS-CoV-2 during an outbreak in a Quebec emergency childcare centre.
- To identify the origins and directionality of viral spread within the ECCC and associated households.
Main Methods:
- Descriptive epidemiology was used to analyze case data.
- Social network visualization and phylogenetic analysis were employed to trace viral lineages.
- RT-PCR and whole genome sequencing confirmed infections and characterized viral strains.
Main Results:
- Two distinct SARS-CoV-2 lineages were introduced into the ECCC.
- The effective reproductive number (Re) was estimated at 1.9, with a mean doubling time of 3.2 days.
- Asymptomatic children were identified as key transmitters, with higher attack rates observed in mothers compared to fathers within households.
Conclusions:
- Asymptomatic children can efficiently transmit SARS-CoV-2, contributing to significant community spread.
- The outbreak demonstrated multiple transmission routes, including adult-to-child, child-to-adult, and child-to-child.
- Findings underscore the importance of considering childcare settings in COVID-19 control strategies.
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 Re = 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.
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