Research Article Vitamin D and COVID-19 susceptibility and severity in the COVID-19 Host Genetics Initiative: A Mendelian randomization study Guillaume Butler-Laporte , Contributed equally to this work with: Guillaume Butler-Laporte, Tomoko Nakanishi Roles Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Software, Validation, Visualization, Writing – original draft, Writing – review & editing Affiliations Lady Davis Institute, Jewish General Hospital, McGill University, Montréal, Québec, Canada, Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montréal, Québec, Canada Contributed equally to this work with: Guillaume Butler-Laporte, Tomoko Nakanishi Roles Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Validation, Visualization, Writing – original draft, Writing – review & editing