The number of confirmed COVID-19 cases in Australia has been doubling every 3-to-4 days. This is not surprising: the slowly-increasing measures put in place over the past week by the federal and state governments will take time to slow the growth of case numbers. But we should be clear: a shutdown of anything that isn’t truly essential will be needed to avoid overwhelming the healthcare system.
In the coming days and weeks, the number of Australians diagnosed with COVID-19 will rise quickly. This will place great pressure on our health services, staff, and infrastructure, including intensive care units (ICUs).
The likelihood that people who are diagnosed with COVID-19 will be admitted to an ICU depends on their age. About 20 per cent of people over 80 will need to be admitted to an ICU, while the rate for 50-to-59 year-olds is 1.2 per cent.1 Given Australia’s demographic make-up, the overall ICU rate is estimated at 2.2 per cent of diagnosed cases.2
The Figure below shows that with Australia’s current rate of doubling of cases every 3-to-4 days, our ICUs will reach current capacity in mid-April. When we hit a trigger point of 12,000 new cases every day, then we know that we will hit our current ICU capacity soon after if new cases continue to grow.
In the scenario of cases doubling every three days, we would reach current ICU capacity on April 11. If cases double every four days instead, we reach ICU capacity a week later on April 18.3 Slowing the growth to doubling every five days would buy another week.
States are already purchasing additional ventilators to double ICU capacity, but machines need staff to operate and monitor them. Trained staff are not immediately available and so some relaxation of enterprise agreement conditions about staffing may be required during the peak of the pandemic. There are also other patients who will require ICU beds, reducing the number of available beds. But, looking at the Figure above, the only thing that matters right now is the rate of growth.
The initial plans to ‘flatten the curve’ would still lead to more than 100,000 new cases per day at the peak of the pandemic. While this approach will buy us time, we will still run out of ICU beds in Australia.
This will force us to confront ethical dilemmas as to who gets admitted to the ICU and for how long, and who remains in a hospital bed with less intensive treatment. These ‘tragic choices’4 that families and health professionals face are the consequences of broader social and political decisions about the toughness of spatial isolation policies. The quicker we can reduce the rate of infection, the better the health system will be able to cope. Older people are more at risk of ICU admission (and death) and so we should be particularly aiming to reduce infection in the elderly.5
Our gloomy ICU forecast is primarily determined by the exponential growth in diagnosed cases. This is what needs to change. The goal should be to bring new cases in Australia down to zero as quickly as possible. All state governments must act decisively and bring in a broad shutdown now.
Co Authors :
- See Table 1 of Impact of non-pharmaceutical interventions (NPIs) to reduce COVID19 mortality and healthcare demand
- Assuming that each age group gets COVID-19 at the same rate. If fewer older people get the virus, the proportion of all people that will be admitted to ICU will be less, and vice versa.
- Higgie and Khan (2020) estimate slightly earlier dates under similar growth scenarios by using a higher rate of ICU admissions (5% rather than 2.2%).
- Calabresi, G. and Bobbitt, P. (1978), Tragic choices: The conflicts society confronts in the allocation of tragically scarce resources (New York: Norton).
- Tony Blakely has highlighted this point: https://pursuit.unimelb.edu.au/articles/the-maths-and-ethics-of-minimising-covid-19-deaths.