COVID-19: Active cases and hospitalisation rates
Hospital capacity planning is a difficult exercise in the best of times. The last couple of months has seen a flurry of activity globally to try and understand the rapidly growing needs and get ahead of the demand through commissioning additional capacity.
I was inspired by the online calculator developed by University of Pennsylvania that clearly illustrated the looming crisis and the impact of social distancing. But this was developed using a mix of assumptions from the early cases in China and Italy. These data were also used in the Doherty Institute models published yesterday.
But our health system is different, and the counting of beds, cases and other elements have localised differences. So how is it panning out in Australia?
Unfortunately, the reporting by States and Territories is lean on detail of the health service impacts, but Victoria has the most comprehensive dataset. As the daily hospitalisation needs are a function of the active cases (not total cases or new cases), this trend is important.
Figure 1 below show the rise and fall of active cases, with them peaking on 31 March 2020. The decline of the active cases has, however, been slower than the decline in new cases, probably reflecting some lag in reporting and changes in the follow-up protocols.
Figure 1: Number of new and active COVID-19 cases per day in Victoria 19 Mar to 8 April 2020
Source: Victorian Department of Health and Human Services
Note: Active cases = Confirmed cases - Recovered cases
Figure 2 shows us the proportion of the active cases in Victoria that are hospitalised. Interestingly, Victoria is the only State that publishes these data (but buried in the daily media release, not on the dashboard). The portion of active cases that are hospitalised has risen from 4 to 9 per cent over the past couple of weeks, with the proportion of these in Intensive Care Units increasing from 15 per cent of hospitalisations to more than 25 per cent. Why the variation in rates?
While Victoria doesn’t report on the proportion of ICU patients on mechanical ventilation. These data are reported by NSW, with 50-60 per cent of ICU patients having mechanical ventilation (Figure 3).
So, maybe the worst of the initial phase is over, with declining number of active cases (mostly from the overseas arrivals). Now with some local data, the epidemiology models can now be recalibrated with real world Australian data.
Figure 2: Hospitalisation rate of active cases and ICU admission rate of COVID-19 hospitalisations per day in Victoria 19 Mar to 8 April 2020
Figure 3: Proportion of Intensive Care Unit patients with mechanical ventilation by day 26 Mar to 8 April 2020, NSW, Australia
Source: NSW Health