The CHILD Cohort COVID-19 Add-On Study

Study will leverage the existing CHILD Cohort Study. All household members from each family will be incited to participate. To accommodate institutional physical distancing policies, the study is designed to minimize participant contact and the need for research staff onsite. Weekly symptom check (by text message): Brief survey will capture COVID-19 signs and symptoms, testing and results, and healthcare utilization. Questions will be aligned with the Government of Canada self-assessment tool and harmonized with international partners. Quarterly CoRonavIruS Health Impact Survey (CRISIS) (7) and body weight: 10-minute CRISIS survey captures COVID-19 exposure, life changes due to the COVID-19 crisis, daily behaviours, emotions and worries, media use and substance use. Each household member will complete the survey; parents will complete on behalf of younger children. Body weight (measured at home) will also be reported. Repeated seroprevalence survey: Use of simple home sampling kit containing volumetric absorption micro-sampling devices (Mitra(R) cartridge device, Neoteryx LLC) to collect a fingerstick blood sample (10 ul; a few drops) for SARS-Cov2 IgG serology testing laboratory. Knowledge Users (Public Health authorities) and virology/serology experts will advise on the best available serology assay at the time of testing, and the investigators will consider testing in a public health lab if possible. Kits will be delivered and returned by mail, and an instructional video will be provided. Results will be returned to participants with appropriate explanation of their clinical relevance, and shared in real time with Knowledge Users to inform modeling efforts and pandemic management The timing and frequency of sero-surveys will be guided by our Knowledge Users depending on the progression of the pandemic. Analysis of recently-collected pre-pandemic bio-samples: To determine the pre-pandemic immune profile of CHILD index children, the investigators will analyze a subset including all cases (asymptomatic and symptomatic) detected by serology and symptom surveys, plus a random subset of uninfected controls (estimated: 400 children in total). The investigators will assess: 1. a panel of innate and adaptive cytokines and chemokines using a commercial multiplex assay, 2. immune cell phenotypes using high dimensional flow cytometry 3. viral antibodies to establish prior/recent infections and cross-reactivity using targeted ELISA assays developed for antibodies to other human beta-coronaviruses