Projecting demand for critical care beds during COVID-19 outbreaks in Canada

Abstract

Background: Increasing numbers of coronavirus disease 2019 (COVID-19) cases in Canada may create substantial demand for hospital admission and critical care. We evaluated the extent to which self-isolation of mildly ill people delays the peak of outbreaks and reduces the need for this care in each Canadian province.

Methods: We developed a computational model and simulated scenarios for COVID-19 outbreaks within each province. Using estimates of COVID-19 characteristics, we projected the hospital and intensive care unit (ICU) bed requirements without self-isolation, assuming an average number of 2.5 secondary cases, and compared scenarios in which different proportions of mildly ill people practised self-isolation 24 hours after symptom onset.

Results: Without self-isolation, the peak of outbreaks would occur in the first half of June, and an average of 569 ICU bed days per 10 000 population would be needed. When 20% of cases practised self-isolation, the peak was delayed by 2-4 weeks, and ICU bed requirement was reduced by 23.5% compared with no self-isolation. Increasing self-isolation to 40% reduced ICU use by 53.6% and delayed the peak of infection by an additional 2-4 weeks. Assuming current ICU bed occupancy rates above 80% and self-isolation of 40%, demand would still exceed available (unoccupied) ICU bed capacity.

Interpretation: At the peak of COVID-19 outbreaks, the need for ICU beds will exceed the total number of ICU beds even with self-isolation at 40%. Our results show the coming challenge for the health care system in Canada and the potential role of self-isolation in reducing demand for hospital-based and ICU care.

Figure 1:

Schematic diagram of the model for natural history of the disease and implementation of self-isolation and hospital admission. Note: ICU = intensive care unit.

Figure 2:

Distribution of the cumulative intensive care unit (ICU) bed days per 10 000 population during the coronavirus disease 2019 (COVID-19) outbreaks in different provinces. Box plots correspond to the level of self-isolation (SI) among mild symptomatic cases: SI = 0% (orange), SI = 20% (blue) and SI = 40% (red). Circles on box plots indicate medians; bars indicate interquartile range (IQR); horizontal lines are extended range from minimum (25th percentile – 1.5 IQR) to maximum (75th percentile + 1.5 IQR). Vertical dashed lines correspond to the average ICU bed days in all provinces without self-isolation (orange line = 569), 20% self-isolation (blue line = 435) and 40% self-isolation (red line = 264). These distributions are based on 500 independent simulations in each scenario.

Figure 3:

Projected week of the outbreak peak (based on the highest daily incidence of new infections) in different provinces. Coloured circles correspond to the level of self-isolation (SI) among mild symptomatic cases.