This is a summary, written by members of the CITF Secretariat, of:

Hohl CM, Rosychuk RJ, Hau JP, Hayward J, Landes M, Yan JW, Ting DK, Welsford M, Archambault PM, Mercier E, Chandra K, Davis P, Vaillancourt S, Leeies M, Small S, Morrison LJ; Canadian COVID-19 Rapid Response Network (CCEDRRN) investigators for the Network of Canadian Emergency Researchers, for the Canadian Critical Care Trials Group. Treatments, resource utilization, and outcomes of COVID-19 patients presenting to emergency departments across pandemic waves: an observational study by the Canadian COVID-19 Emergency Department Rapid Response Network (CCEDRRN). CJEM. 2022 Jun;24(4):461-462. doi:

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

A CITF-funded study, published in the Canadian Journal of Emergency Medicine, found that substantially fewer patients were admitted to critical care and put on mechanical ventilation in the second wave of the pandemic than in the first – with no negative impact on mortality. This is after adjusting for differences in patient characteristics and disease severity. This study offers real-world evidence that adjustments in medical practice during the second pandemic wave were safe and associated with lower resource utilization, while maintaining positive outcomes for patients. Both waves involved the circulating wildtype SARS-CoV-2 strain. This study was led by Dr. Corinne Hohl (University of British Columbia) in collaboration with Canadian COVID-19 Emergency Department Rapid Response Network (CCEDRRN) investigators.

The study’s aim was to describe and compare treatments, acute care utilization, and outcomes of emergency department (ED) patients with COVID-19 across two pandemic waves. The first wave was defined as between March 1 and June 30, 2020, and the second wave was between July 1 and December 31, 2020 (both waves involved the circulating wildtype SARS-CoV-2 strain).

Key findings:

  • Patients presenting to the ED in the second wave were younger (mean age 53 years old), had fewer comorbidities, met fewer criteria for severe COVID-19, and more were discharged from the ED, compared to during the first wave. They were less likely to arrive from long-term care, report an occupational exposure, travel-related infection, or an institutional exposure.
  • After adjusting for differences in patient characteristics and disease severity, steroid use increased and antimalarials and antivirals were used less frequently, while antibiotic use stayed the same in the second wave. This reflects rapid uptake of evidence-based therapies and less use of experimental therapies in the second wave.
  • Invasive mechanical ventilation was used less frequently and had a shorter duration during the second wave compared to the first wave.
  • After adjusting for differences in patient characteristics and disease severity, the odds of hospitalization and critical care admission decreased during the second wave, with no increase in mortality.
  • Despite shorter stays in the second wave, readmissions after hospital discharge were rare and similar across both waves.

The study provides real-world evidence of the dynamic adaptation of COVID-19 treatment strategies, showcasing the rapid uptake of evidence-based therapies, reduced reliance on antivirals and antimalarials, and the optimization of healthcare resource utilization without compromising patient outcomes.

This observational study enrolled 9, 967 COVID-19 patients presenting to 46 EDs participating in the CCEDRRN between March 1 and December 31, 2020. These included patients from Quebec, Alberta, and British Columbia.