PT  - JOURNAL ARTICLE
AU  - Lee, Terry
AU  - Cheng, Matthew P.
AU  - Vinh, Donald C.
AU  - Lee, Todd C.
AU  - Tran, Karen C.
AU  - Winston, Brent W.
AU  - Sweet, David
AU  - Boyd, John H.
AU  - Walley, Keith R.
AU  - Haljan, Greg
AU  - McGeer, Allison
AU  - Lamontagne, Francois
AU  - Fowler, Robert
AU  - Maslove, David M.
AU  - Singer, Joel
AU  - Patrick, David M.
AU  - Marshall, John C.
AU  - Burns, Kevin D.
AU  - Murthy, Srinivas
AU  - Mann, Puneet K.
AU  - Hernandez, Geraldine
AU  - Donohoe, Kathryn
AU  - Russell, James A.
AU  - ,
TI  - Outcomes and characteristics of patients hospitalized for COVID-19 in British Columbia, Ontario and Quebec during the Omicron wave
AID  - 10.9778/cmajo.20220194
DP  - 2023 Jul 01
TA  - CMAJ Open
PG  - E672--E683
VI  - 11
IP  - 4
4099  - http://www.cmajopen.ca/content/11/4/E672.short
4100  - http://www.cmajopen.ca/content/11/4/E672.full
SO  - CMAJ2023 Jul 01; 11
AB  - Background: Omicron is the current predominant variant of concern of SARS-CoV-2. We hypothesized that vaccination alters outcomes of patients hospitalized with COVID-19 during the Omicron wave and that these patients have different characteristics and outcomes than in previous waves.Methods: This is a substudy of the Host Response Mediators in Coronavirus (COVID-19) Infection (ARBs CORONA I) trial, which included adults admitted to hospital with acute COVID-19 up to July 2022 from 9 hospitals in British Columbia, Ontario and Quebec. We excluded emergency department visits without hospital admission, readmissions and admissions for another reason. Using adjusted regression analysis, we compared mortality and organ dysfunction between vaccinated (≥ 2 doses) and unvaccinated patients during the Omicron wave, as well as between all patients in the Omicron and first 3 waves of the COVID-19 pandemic.Results: During the Omicron wave, 28-day mortality was significantly lower in vaccinated (n = 19/237) than unvaccinated hospitalized patients (n = 12/127) (adjusted odds ratio [OR] 0.36, 95% confidence interval [CI] 0.15–0.89); vaccinated patients had lower risk of admission to the intensive care unit, invasive ventilation and acute respiratory distress syndrome and shorter hospital length of stay. Patients hospitalized during the Omicron wave had more comorbidities than in previous waves, and lower 28-day mortality than in waves 1 and 2 (adjusted OR 0.38, 95% CI 0.24–0.59; and 0.42, 95% CI 0.26–0.65) but not wave 3 (adjusted OR 0.81, 95% CI 0.43–1.51) and had less organ dysfunction than in the first 2 waves.Interpretation: Patients who were at least double vaccinated had lower mortality than unvaccinated patients hospitalized during the Omicron wave. Patients hospitalized during the Omicron wave had more chronic disease and lower mortality than in the first 2 waves, but not wave 3. Changes in vaccination, treatments and predominant SARS-CoV-2 variant may have decreased mortality in patients hospitalized during the Omicron wave.