Investigating SARS-CoV-2 infection and the health and psychosocial impact of the COVID-19 pandemic in the Canadian CHILD Cohort: study methodology and cohort profile

Abstract Background The COVID-19 pandemic is affecting all Canadian families, with some impacted differently than others. Our study aims to: 1) determine the prevalence and transmission of SARS-CoV-2 infection among Canadian families, 2) identify predictors of infection susceptibility and severity of SARS-CoV-2 and 3) identify health and psychosocial impacts of the COVID-19 pandemic. Methods This study builds upon the CHILD Cohort Study, an ongoing multi-ethnic general population prospective cohort consisting of 3454 Canadian families with children born in Vancouver, Edmonton, Manitoba, and Toronto between 2009-12. During the pandemic, 1462 CHILD households (5378 individuals) consented to participate in the CHILD COVID-19 Add-On Study involving: (1) brief biweekly surveys about COVID-19 symptoms and testing; (2) quarterly questionnaires assessing COVID-19 exposure, testing and vaccination status, physical and mental health, and pandemic-driven life changes; (3) in-home biological sampling kits to collect blood and stool. Mean ages were 9 years (range 0-17) for children and 43 years (range 18-85) for adults. Prevalence of SARS-CoV-2 infection will be estimated from survey data and confirmed through serology testing. We will combine these new data with a wealth of pre-pandemic CHILD data and use multivariate modelling and machine learning methods to identify risk and resilience factors for susceptibility and severity to the direct and indirect effects of the pandemic. Interpretation Our short-term findings will inform key stakeholders and knowledge users to shape current and future pandemic responses. Additionally, this study provides a unique resource to study the long-term impacts of the pandemic as the CHILD Cohort Study continues.