ArticleCMAJ open
The impact of shifting demographics, variants of concern and vaccination on outcomes during the first 3 COVID-19 waves in Alberta and Ontario: a retrospective cohort study.
Article in CMAJ open. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 15 papers.
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Who cites it
15 citing papers in PubMed.
- Sociodemographic factors that influence COVID-19 healthcare utilization and costs in Alberta, Canada: a population-based study using the Alberta COVID-19 analytics and research database.Frontiers in health services · 2026Article
- A comparative study between first three waves of COVID-19 pandemic with respect to risk factors, initial clinic-demographic profile, severity and outcome.Journal of family medicine and primary care · 2024Article
- The impact of the COVID-19 pandemic on transfers between long-term care and emergency departments across Alberta.BMC emergency medicine · 2024Article
- Digital PCR to Measure SARS-CoV-2 RNA, Variants, and Outcomes in Youth.Journal of the Pediatric Infectious Diseases Society · 2023Article
- Sequential multi-omics analysis identifies clinical phenotypes and predictive biomarkers for long COVID.Cell reports. Medicine · 2023Article
- Emergency Visits or Hospitalizations for Cardiovascular Diagnoses in the Post-Acute Phase of COVID-19.JACC. Advances · 2023Article
- Healthcare utilization and adverse outcomes stratified by sex, age and long-term care residency using the Alberta COVID-19 Analytics and Research Database (ACARD): a population-based descriptive study.BMC infectious diseases · 2023Article
- The burden of incidental SARS-CoV-2 infections in hospitalized patients across pandemic waves in Canada.Scientific reports · 2023Article
- Clinical Characteristics and Outcomes of Patients with Acute Respiratory Failure Due to SARS-CoV-2 Interstitial Pneumonia Treated with CPAP in a Medical Intermediate Care Setting: A Retrospective Observational Study on Comparison of Four Waves.Journal of clinical medicine · 2023Article
- Cross-Canada Variability in Blood Donor SARS-CoV-2 Seroprevalence by Social Determinants of Health.Microbiology spectrum · 2023Article
- Prediction of Symptomatic Severe Acute Respiratory Syndrome Coronavirus 2 Infection by Quantitative Digital Polymerase Chain Reaction Normalized to International Units.Open forum infectious diseases · 2022Article
- Evolution of the Clinical Profile and Outcomes of Unvaccinated Patients Affected by Critical COVID-19 Pneumonia from the Pre-Vaccination to the Post-Vaccination Waves in Italy.Pathogens (Basel, Switzerland) · 2022Article
- The risk of death or unplanned readmission after discharge from a COVID-19 hospitalization in Alberta and Ontario.CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne · 2022Article
- The Role of Serology Testing in the Context of Immunization Policies for COVID-19 in Latin American Countries.Viruses · 2021Review
- Article
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Authors and funding
7 authors.
Funding
Abstract
backgroundIn Canada, published outcome data for COVID-19 come largely from the first 2 waves of the pandemic. We examined changes in demographics and 30-day outcomes after SARS-CoV-2 infection during the first 3 pandemic waves in Alberta and Ontario; for wave 3, we compared outcomes between those infected with a variant of concern and those infected with the original "wild-type" SARS-CoV-2.
methodsWe conducted a population-based retrospective cohort study using linked health care data sets in Alberta and Ontario. We identified all-cause hospitalizations or deaths within 30 days after a positive result on a reverse transcription polymerase chain reaction test for SARS-CoV-2 in individuals of any age between Mar. 1, 2020, and June 30, 2021, with genomic confirmation of variants of concern. We compared outcomes in wave 3 (February 2021 to June 2021) with outcomes in waves 1 and 2 combined (March 2020 to January 2021) after adjusting for age, sex and Charlson Comorbidity Index score. Using wave 3 data only, we compared outcomes by vaccination status and whether or not the individual was infected with a variant of concern.
resultsCompared to those infected with SARS-CoV-2 during waves 1 and 2 (
interpretationWe observed a shift among those infected with SARS-CoV-2 toward younger patients with fewer comorbidities, a shorter length of hospital stay and lower mortality risk as the pandemic evolved in Alberta and Ontario; however, infection with a variant of concern was associated with a substantially higher risk of hospitalization or death. As variants of concern emerge, ongoing monitoring of disease expression and outcomes among vaccinated and unvaccinated individuals is important to understand the phenotypes of COVID-19 and the anticipated burdens for the health care system.
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