RT Journal Article SR Electronic T1 Initial health care costs for COVID-19 in British Columbia and Ontario, Canada: an interprovincial population-based cohort study JF CMAJ Open JO CMAJ FD Canadian Medical Association SP E818 OP E830 DO 10.9778/cmajo.20210328 VO 10 IS 3 A1 Tsui, Teresa C.O. A1 Zeitouny, Seraphine A1 Bremner, Karen E. A1 Cheung, Douglas C. A1 Mulder, Carol A1 Croxford, Ruth A1 Del Giudice, Lisa A1 Lapointe-Shaw, Lauren A1 Mendlowitz, Andrew A1 Wong, William W.L. A1 Perlis, Nathan A1 Sander, Beate A1 Teckle, Paulos A1 Tomlinson, George A1 Walker, Jennifer D. A1 Malikov, Kamil A1 McGrail, Kimberlyn M. A1 Peacock, Stuart A1 Kulkarni, Girish S. A1 Pataky, Reka E. A1 Krahn, Murray D. YR 2022 UL http://www.cmajopen.ca/content/10/3/E818.abstract AB Background: COVID-19 imposed substantial health and economic burdens. Comprehensive population-based estimates of health care costs for COVID-19 are essential for planning and policy evaluation. We estimated publicly funded health care costs in 2 Canadian provinces during the pandemic’s first wave.Methods: In this historical cohort study, we linked patients with their first positive SARS-CoV-2 test result by June 30, 2020, in 2 Canadian provinces (British Columbia and Ontario) to health care administrative databases and matched to negative or untested controls. We stratified patients by highest level of initial care: community, long-term care, hospital (without admission to the intensive care unit [ICU]) and ICU. Mean publicly funded health care costs for patients and controls, mean net (attributable to COVID-19) costs and total costs were estimated from 30 days before to 120 days after the index date, or to July 31, 2020, in 30-day periods for patients still being followed by the start of each period.Results: We identified 2465 matched people with a positive test result for SARS-CoV-2 in BC and 28 893 in Ontario. Mean age was 53.4 (standard deviation [SD] 21.8) years (BC) and 53.7 (SD 22.7) years (Ontario); 55.7% (BC) and 56.1% (Ontario) were female. Net costs in the first 30 days after the index date were $22 010 (95% confidence interval [CI] 19 512 to 24 509) and $15 750 (95% CI 15 354 to 16 147) for patients admitted to hospital, and $65 828 (95% CI 58 535 to 73 122) and $56 088 (95% CI 53 721 to 58 455) for ICU patients in BC and Ontario, respectively. In the community and long-term care settings, net costs were near 0. Total costs for all people, from 30 days before to 30 days after the index date, were $22 128 330 (BC) and $175 778 210 (Ontario).Interpretation: During the first wave, we found that mean costs attributable to COVID-19 were highest for patients with ICU admission and higher in BC than Ontario. Reducing the number of people who acquire COVID-19 and severity of illness are required to mitigate the economic impact of COVID-19.