Background: In 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 …

Importance With 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 …

Recent SARS-CoV-2 variants have been associated with lower severity. 1-3 Estimating the
true severity of SARS-CoV-2 across time is difficult due to its rapid mutations, 4, 5 changing …

Background: The COVID-19 pandemic is dominated by variant viruses; the resulting impact
on disease severity remains unclear. Using a retrospective cohort study, we assessed the …

Background The incidence of and risk factors for severe clinical outcomes with the Omicron
(B. 1.1. 529) SARS-CoV-2 variant have not been well-defined. Methods We conducted a …

Background Population-level vaccine efficacy is a critical component of understanding
COVID-19 risk, informing public health policy, and mitigating disease impacts. Unlike …

Background People with immune dysfunction are at higher risk of severe outcomes from
COVID-19 infection, but relatively little epidemiologic information is available for mostly …

Summary Background The SARS-CoV-2 variant of concern, omicron, appears to be less
severe than delta. We aim to quantify the differences in symptom prevalence, risk of hospital …

Objective To determine how the severity of successively dominant SARS-CoV-2 variants has
changed over the course of the COVID-19 pandemic. Design Prospective cohort analysis …

Background The coronavirus disease 2019 (COVID-19) pandemic is dominated by variant
viruses; the resulting impact on disease severity remains unclear. Using a retrospective …