Wingert A, Pillay J, Gates M, et al. - Via this rapid review, researchers sought to ascertain the magnitude of link between potential risk factors and COVID-19 severity, to inform vaccine prioritisation in Canada. They selected eligible studies (performed in high-income countries and employed multivariate analyses) from Ovid MEDLINE(R) ALL, Epistemonikos COVID-19 in L·OVE Platform, McMaster COVID-19 Evidence Alerts and websites. They found low or moderate certainty evidence for a large (≥ 2-fold) magnitude of link between hospitalisation in individuals suffering from COVID-19, and: obesity class III, heart failure, diabetes, chronic kidney disease, dementia, age > 45 years, male gender, black race/ethnicity (vs non-Hispanic white), homelessness and low income. For mortality, there may be a large magnitude of link with liver disease, Bangladeshi ethnicity (relative to British white), age >45 years, age >80 years (vs 65–69 years) and male gender among 20–64 years (but not older). Possibly, the most crucial risk factor for severe outcomes is increasing age (particularly > 60 years). To gain better understanding of the magnitude of links for severity of COVID-19 with various other factors, high-quality primary research accounting for multiple confounders should be conducted.