Risk factors for severity of COVID-19: a rapid review to inform vaccine prioritisation in Canada

OBJECTIVES: Rapid review to determine the magnitude of association between potential risk factors and severity of COVID-19, to inform vaccine prioritisation in Canada. SETTING: Ovid MEDLINE(R) ALL, Epistemonikos COVID-19 in L·OVE Platform, McMaster COVID-19 Evidence Alerts and websites were searched to 15 June 2020. Eligible studies were conducted in high-income countries and used multivariate analyses. PARTICIPANTS: After piloting, screening, data extraction and quality appraisal were performed by a single experienced reviewer. Of 3740 unique records identified, 34 were included that reported on median 596 (range 44–418 794) participants, aged 42–84 years. 19/34 (56%) were good quality. OUTCOMES: Hospitalisation, intensive care unit admission, length of stay in hospital or intensive care unit, mechanical ventilation, severe disease, mortality. RESULTS: Authors synthesised findings narratively and appraised the certainty of the evidence for each risk factor–outcome association. There was low or moderate certainty evidence for a large (≥2-fold) magnitude of association between hospitalisation in people with 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. Age >60 and >70 years may be associated with large increases in mechanical ventilation and severe disease, respectively. For mortality, a large magnitude of association may exist with liver disease, Bangladeshi ethnicity (vs British white), age >45 years, age >80 years (vs 65–69 years) and male gender among 20–64 years (but not older). Associations with hospitalisation and mortality may be very large (≥5-fold) for those aged ≥60 years. CONCLUSIONS: Increasing age (especially >60 years) may be the most important risk factor for severe outcomes. High-quality primary research accounting for multiple confounders is needed to better understand the magnitude of associations for severity of COVID-19 with several other factors. PROSPERO REGISTRATION NUMBER: CRD42020198001.