Outcomes and characteristics of patients hospitalized for COVID-19 in British Columbia, Ontario and Quebec during the Omicron wave (original) (raw)
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BackgroundDescription of risk factors of severe acute COVID-19 outcomes with the consideration of vaccination status in the era of the Omicron variant of concern are limited.ObjectivesTo examine the association of age, sex, underlying medical conditions, and COVID-19 vaccination with hospitalization, intensive-care unit (ICU) admission, or death due to the disease, using data from a period when Omicron was the dominant strain.MethodsA population-based case-control study based on administrative health data, that included confirmed COVID-19 patients during January (2022) in Alberta, Canada. Patients who were non-residents, without the provincial healthcare insurance coverage, or ≤18 years of age were excluded. Patients with any severe outcome were the cases; and those without any hospitalization, ICU admission, or death were controls. Adjusted odds ratios, of the explanatory factors of a severe outcome, were estimated using a logistic regression model.ResultsThere were 90,989 COVID-19...
2021
While it is now evident that Omicron is rapidly replacing Delta, largely due to immune escape, it is less clear how the severity of Omicron compares to Delta. In Ontario, we sought to examine hospitalization and death associated with Omicron, as compared to cases infected with Delta. We conducted a matched cohort study, considering time to hospitalization or death as the outcome. Cases were matched on gender, age, vaccination status, health region and onset date. We identified 29,594 Omicron cases that met eligibility criteria, of which 11,622 could be matched with at least one Delta case (N=14,181). There were 59 (0.51%) hospitalizations and 3 (0.03%) deaths among matched Omicron cases, compared to 221 (1.6%) hospitalizations and 17 (0.12%) deaths among matched Delta cases. The risk of hospitalization or death was 65% lower (hazard ratio, HR=0.35, 95%CI: 0.26, 0.46) among Omicron cases compared to Delta cases, while risk of intensive care unit admission or death was 83% lower (HR=0...
SSRN Electronic Journal
Objective To compare the population rate of COVID-19 and influenza hospitalizations by age, COVID-19 vaccine status and pandemic phase. Design Observational retrospective study Setting Residents of British Columbia (population 5.3 million), Canada Participants Hospitalized patients due to COVID-19 or historical influenza Main outcome measures This population based study in a setting with universal healthcare coverage, used COVID-19 case and hospital data for COVID-19 and influenza. Admissions were selected from March 2020 to February 2021 for the annual cohort and the first 8 weeks of 2022 for the peak cohort of COVID-19 (Omicron era). Influenza annual and peak cohorts were from three years with varying severity: 2009/10, 2015/16, and 2016/17. We estimated hospitalization rates per 100,000 population by age group. Results Similar to COVID-19 with median age 66 (Q1-Q3 44-80), influenza 2016/17 mostly affected older adults, with median age 78 (64-87). COVID-19 and influenza 2016/17 hospitalization rate by age group were "J" shaped. The rates for mostly unvaccinated COVID-19 patients in 2020/21 in the context of public health restrictions were significantly higher than influenza among individuals 30 to 69 years of age, and comparable to a severe influenza year (2016/17) among 70+. In early 2022 (Omicron peak), rates primarily due to COVID-19 among vaccinated adults were comparable with influenza 2016/17 in all age groups while rates among unvaccinated COVID-19 patients were still higher than influenza among 18+. In the pediatric population, COVID-19 hospitalization rates were similar to or lower than influenza. Conclusions Our paper highlighted the greater population-level impact of COVID-19 compared with influenza in terms of adult hospitalizations, especially among those unvaccinated. However, influenza had greater impact than COVID-19 among <18 regardless of vaccine status or the circulating variant. .
CMAJ Open
, the World Health Organization has recognized SARS-CoV-2 variants of concern. 1,2 Although reports from the United Kingdom, Europe and China have suggested that infections with variants of concern are more severe, 3-12 until very recently there has been a paucity of evidence from North America. 13,14 In Canada, wave 3 of the COVID-19 pandemic occurred between February and June 2021 (www.covid19tracker.ca) and was driven by variants of concern, particularly the Alpha (B.1.1.7) and Delta (B.1.617) variants; the Gamma (P1) and Beta (B.1.351) variants were seen largely in travellers returning from regions where these were more common. The Alpha variant has been associated with higher risks of mortality (approximately 64% in a UK case-control study and 59% in a UK cohort study) 5,6 and hospitalization (52% in a UK cohort study 6 and approximately 70% in European Surveillance System data). 7 However, the UK studies 5,6 relied solely on findings from community tests; they omitted up to 70% of COVID-19 deaths, which occurred in patients diagnosed after hospital admission. In the European study, 7 less than 1%
2021
ABSTRACTImportanceWith the emergence of more transmissible SARS-CoV-2 variants of concern (VOC), there is an urgent need for evidence about disease severity and the health care impacts of VOC in North America, particularly since a substantial proportion of the population have declined vaccination thus far.ObjectiveTo examine 30-day outcomes in Canadians infected with SARS-CoV-2 in the first year of the pandemic and to compare event rates in those with VOC versus wild-type infection.DesignRetrospective cohort study using linked healthcare administrative datasets.SettingAlberta and Ontario, the two Canadian provinces that experienced the largest third wave in the spring of 2021.ParticipantsAll individuals with a positive SARS-CoV-2 reverse transcriptase polymerase chain reaction swab from March 1, 2020 until March 31, 2021, with genomic confirmation of VOC screen-positive tests during February and March 2021 (wave 3).Exposure of InterestVOC versus wild type SARS-CoV-2Main Outcomes and...
Scientific Reports
Many health authorities differentiate hospitalizations in patients infected with SARS-CoV-2 as being “for COVID-19” (due to direct manifestations of SARS-CoV-2 infection) versus being an “incidental” finding in someone admitted for an unrelated condition. We conducted a retrospective cohort study of all SARS-CoV-2 infected patients hospitalized via 47 Canadian emergency departments, March 2020-July 2022 to determine whether hospitalizations with “incidental” SARS-CoV-2 infection are less of a burden to patients and the healthcare system. Using a priori standardized definitions applied to hospital discharge diagnoses in 14,290 patients, we characterized COVID-19 as (i) the “Direct” cause for the hospitalization (70%), (ii) a potential “Contributing” factor for the hospitalization (4%), or (iii) an “Incidental” finding that did not influence the need for admission (26%). The proportion of incidental SARS-CoV-2 infections rose from 10% in Wave 1 to 41% during the Omicron wave. Patients...
International Journal of Infectious Diseases
Objectives: With the uptake of COVID-19 vaccines, there is a need for population-based studies to assess risk factors for COVID-19-related hospitalization after vaccination and how they differ from unvaccinated individuals. Methods: We used data from the British Columbia COVID-19 Cohort, a population-based cohort that includes all individuals (aged ≥18 years) who tested positive for SARS-CoV-2 by real-time reverse transcription-polymerase chain reaction from January 1, 2021 (after the start of vaccination program) to December 31, 2021. We used multivariable logistic regression models to assess COVID-19-related hospitalization risk by vaccination status and age group among confirmed COVID-19 cases. Results: Of the 162,509 COVID-19 cases included in the analysis, 8,546 (5.3%) required hospitalization. Among vaccinated individuals, an increased odds of hospitalization with increasing age was observed for older age groups, namely those aged 50-59 years (odds ratio [OR] = 2.95, 95% confidence interval [CI]: 2.01-4.33), 60-69 years (OR = 4.82, 95% CI: 3.29, 7.07), 70-79 years (OR = 11.92, 95% CI: 8.02, 17.71), and ≥80 years (OR = 24.25, 95% CI: 16.02, 36.71). However, among unvaccinated individuals, there was a graded increase in odds of hospitalization with increasing age, starting at age group 30-39 years (OR = 2.14, 95% CI: 1.90, 2.41) to ≥80 years (OR = 41.95, 95% CI: 35.43, 49.67). Also, comparing all the age groups to the youngest, the observed magnitude of association was much higher among unvaccinated individuals than vaccinated ones. Conclusion: Alongside a number of comorbidities, our findings showed a strong association between age and COVID-19-related hospitalization, regardless of vaccination status. However, age-related hospitalization risk was reduced twofold by vaccination, highlighting the need for vaccination in reducing the risk of severe disease and subsequent COVID-19-related hospitalization across all population groups.
CMAJ Open, 2021
U nderstanding local epidemiology and resource use implications of coronavirus disease 2019 (COVID-19) is critical to inform mitigation strategies throughout the pandemic. Appropriate allocation of acute care resources for all patients and the ability to use tailored public health measures to minimize adverse effects resulting from broad restrictions are key concerns. 1-3 Population-level studies in Ontario to date describe several aspects of the first wave, including age-and sex-specific descriptive studies for testing; cases and outcomes up to May 26, 2020; 4 hospital admissions up to June 17, 2020 (preprint); 5 mortality using cremation data in a time series up to June 30, 2020 (preprint); 6 and prediction tools using cases up until May 15, 2020. 7 However, as the COVID-19 pandemic evolves, current data on health outcomes and use of acute care resources across stages of the pandemic are warranted. The objective of our study was to describe the demographic characteristics of individuals testing positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Ontario between Mar. 1 and Sept. 30, 2020, and to provide estimates of age-and sex-specific use of acute care resources in patients with COVID-19 (hospital admission, intensive Demographic characteristics, acute care resource use and mortality by age and sex in patients with COVID-19 in Ontario, Canada: a descriptive analysis