Competing interests: Alexandra Binnie reports receiving research grants from the Canadian Institutes of Health Research (CIHR) and the Physicians Services Incorporated Foundation. Sergio Borgia reports receiving honoraria from Gilead Sciences and GSK. Yiorgos Alexandros Cavayas reports receiving a grant from CIHR. Matthew Cheng reports receiving grants from the McGill Interdisciplinary Initiative in Infection and Immunity and from CIHR, during the conduct of the study (payments made to the institution). Dr. Cheng also reports receiving personal fees from AstraZeneca, outside the submitted work; and from Nplex Biosciences and GEn1E lifesciences (in the form of stock options for being a member of the scientific advisory board) outside the submitted work. Dr. Cheng co-founded Kanvas Biosicences and owns equity in the company, and reports 3 patents pending. John Conly reports receiving grants from CIHR, Pfizer, the World Health Organization (WHO), Sunnybrook Research Institute, University of Calgary, and the Calgary Health Foundation. Dr. Conly also reports receiving support to attend the Think Tank Meeting 2019. Dr. Conly is a member and Chair of the WHO Infection Prevention and Control Research and Development Expert Group for COVID-19, a member of the WHO Health Emergencies Programme (WHE) Ad-hoc COVID-19 IPC Guidance Development Group, and a member of the Cochrane Acute Respiratory Infections Group. Madeleine Durand reports receiving grants from CIHR and the Fonds Recherche du Québec–Santé (FRQS). Rob Fowler reports receiving a grant from CIHR for the CATCO trial and is the H. Barrie Fairley Professor of Critical Care at the University Health Network. Michael Fralick reports receiving multiple grants from CIHR and support from grants from the Canadian military for clinical trials to identify treatments for COVID-19 (payments made to institution). Dr. Fralick is a paid consultant for a start-up company called Proof DiagnosticsDx, which has created a point-of-care testing device using CRISPR for COVID-19. Holly Hoang reports receiving payment from CATCO Sunnybrook to fund research assistant (payment made to institution) and a research grant from Covenant Health Research Centre. Marina Klein reports receiving grants from Gilead, ViiV Healthcare, Merck and AbbVie for investigator-initiated studies, and consulting fees from Gilead, ViiV Healthcare, Merck and AbbVie, all outside the submitted work. Todd Lee reports receiving operating grants from CIHR and McGill Interdisciplinary Initiative in Infection and Immunity (MI4), and research salary support from FRQS. Alexandra Lostun reports receiving per-case funding to cover the costs of enrolling patients (paid to institution, North York General Hospital). François Carrier reports receiving grants from the Instituts de recherche en santé du Canada and the Canadian Donation and Transplantation Research Program, and a grant and salary support from FRQS. Marlee McGuinty reports receiving speaking fees from Merck. Srinivas Murthy reports receiving a grant from CIHR, during the conduct of the study, and is the Health Research Foundation and Innovative Medicines Canada Chair in Pandemic Preparedness Research. Conar O’Neil reports receiving conference sponsorship from Gilead Sciences, and is a member of a Gilead Sciences advisory board. Jesse Papenburg reports receiving a grant from CIHR, during the conduct of the study, as well as research grants and contracts from AbbVie and research contracts (site investigator for clinical trial) from MedImmune, Merck and Sanofi Pasteur. Dr. Papenburg has received consulting fees from Merck for an ad hoc advisory board meeting, and honoraria for presentations from Seegene, AbbVie and AstraZeneca. Dr. Papenburg is also a voting member of the National Advisory Committee on Immunization. Ken Kuljit S. Parhar reports receiving a CIHR project grant, Alberta Innovates grant and Alberta Health Innovation Implementation and Spread grant (all paid to institution). Seema Nair Parvathy reports receiving funding from St. Joseph’s Health Care Foundation and London Health Sciences Foundation. Moira Rushton-Marovac reports receiving advisory board honoraria from Gilead. Marina Salvadori reports being an employee of the Public Health Agency of Canada. Makeda Semret reports receiving support from the McGill MI4 for the clinical research platform through which CATCO was supported at the McGill University Health Centre. Ameeta Singh reports receiving consulting fees from Gilead for membership of an advisory board. Ranjani Somayaji reports receiving contract research funding from Sunnybrook Research Institute, University of Calgary and Calgary Health Foundation, and clinical research funding from CIHR and the Cystic Fibrosis Foundation. Dr. Somayaji also reports participation on an oncovir data monitoring safety board. Darrell Tan reports receiving grants from AbbVie (in-kind drug only) and Gilead (in-kind drug and grants to institution), and a contract between GSK and the institution for clinical trials. Alain Tremblay reports receiving contract research funding from the Sunnybrook Research Institute, and grants for COVID-19 clinical trials from the University of Calgary and Calgary Health Foundation. Alexis Turgeon reports receiving a grant from CIHR. Jason Weatherald reports receiving grants (paid to institution) and consulting fees (paid to Dr. Weatherald) from Janssen and Actelion, as well as honoraria and travel support from Janssen. Dr. Weatherald has served on advisory boards for Janssen and Acceleron (paid) and on a Data Safety Monitoring Board for Université Laval (unpaid). Dr. Weatherald also reports membership of the Medical Advisory Committee of the Pulmonary Hypertension Association of Canada, and is a shareholder of Precision Lung Consultants and Diagnostics. Cedric Yansouni reports receiving grants from FRQS and consulting fees from Medicago Inc. Dr. Yansouni also reports participation in a Medicago Inc. Independent Data Monitoring Committee and held the role of scientific advisor for the COVID-19 Immunity Task Force. No other competing interests were declared.