Where is the data on whether Australia aims to squash or flatten the curve?
Wednesday, Apr 1, 2020, 03:03 AM | Source: Pursuit
By Tony Blakely
Australia has some of the best infectious disease modellers in the world. But, at the moment, we are not hearing what they have to say at the very time we need to know what they're thinking – a serious pandemic.
The first communication principle in the Australian Pandemic Plan (prepared just last year) is "openness and transparency".
But at the moment, the public and health experts not inside the Canberra bubble (those not privy to Australian Health Protection Principal Committee (AHPPC) papers) are out of the loop.
So much for openness and transparency.
What has happened here? There are confidentiality clauses in contracts that give the Government control over the flow of information.
And how did that happen? This will be a question of an inquiry at the end of the pandemic. But here is my guess.
As an epidemiologist who has moved to the lucky country from the land of COVID elimination that is currently New Zealand, I have been struck by how tightly data is guarded in Australia.
The Federal government does not share with the States, and on it goes. If my suspicion is correct, a possible unintended positive consequence of this pandemic could be sorting this data mess out in Australia.
This week, Deputy Chief Medical Officer, Paul Kelly, announced that greater transparency and access to the models is coming – and presumably we will be able to directly hear from Australia's A-Team pandemic modellers.
Because the types of questions that the public wants answered soon are going to need these sophisticated models. Questions like "how and when will small rural communities need to take extra measures?", and "what is the best way to allow essential services into aged care homes while protecting their residents?".
We had been assuming Australia was 'flattening the curve' to achieve herd immunity with minimal deaths and within health service capacity. As of Sunday night, it seems we are instead more severely squashing the curve.
How do we know this?
Statements by Chief Medical Officer Brendan Murphy reveal it: "we have had a somewhat slowing of the growth in the epidemiology curve, but it's not enough. We have to slow it further.
And we have to stop the thing that's worrying us most, which is community transmission... And hopefully these early signs of flattening will mean that we can keep going in getting a reduction in the rate of increase every day."
If we were flattening the curve to achieve herd immunity without over-burdening the health system, we would let the number of cases rise to a level that our health services can manage, and let the population become infected at a manageable rate.
Australia's daily COVID-19 case rates are currently beneath what is necessary to ride the epidemic out to herd immunity – if that is our goal.
But the policy announcements of the last few days are closer to an eradication or elimination strategy. For example, stopping community transmission.
New Zealand hit go on their elimination plan as soon as community transmission started. Australia has not been quite as proactive, but our level of social distancing now is not far off that in New Zealand.
Assuming the daily cases slow further in the next few days, this buys us time to plan for and decide what to do next.
This could play out in a number of different ways.
We could see a late and valiant attempt at elimination – with likely low chance of success.
Or, conversely, in a couple of weeks' time, a loosening up of social distancing if rates are still low to generate sustainable daily caseloads to ride this epidemic out; this means flattening the curve towards herd immunity – with our health services better stocked with equipment and hopefully more evidence on effective treatments.
Or Australia could continue squashing the curve for months and months till sometime in 2021 (with a muted epidemic or two along the way) until a vaccine is available – with less mortality but also much greater societal and economic cost.
All options have merit, and I suspect all are being considered. So, why are we not just letting the caseloads go up now and ride this thing out? Many reasons.
One is the maths.
Let's assume that we will have exquisite control of the epidemic, changing our policy settings daily to ensure that the number of intensive care unit (ICU) admissions in three weeks (factoring in the lag from policy change to change in ICU rates) is exactly the number we want.
Then, backing out of the Imperial College model, the percentage of all infected people that will require ICU care is about 1.6 per cent by my deductions, assuming constant infections rates by age in Australia.
Then assuming 60 per cent of the population needing to be infected to achieve herd immunity, an average of 10 days per COVID ICU admission and 4000 ICU beds dedicated to COVID by the end of May (a doubling of capacity) – my calculations suggest it will take until February next year to ride it out.
Could we do better than this if flattening the curve to herd immunity?
Yes, by measures such as doubling again the ICU capacity, protecting our over 60-year-olds so they have only 20 per cent infection rates, reducing ICU admission times and waiting for better treatments to come on line.
For example, 'just' doubling again ICU capacity to 8000 beds will bring the end of a managed epidemic back to October this year – if we were to loosen up controls now. This isn't something I'm necessarily recommending, just explaining.
Accurately achieving ICU targets will be challenging with some overshoots and undershoots – 'exquisite' control is unlikely, so a safety margin will be required.
This is really hard decision-making, and maybe buying time 'squashing the curve', until we understand better the risks and benefits of options is best for now.
But Australians still deserve to be told what is going on.
So, until the modelling A-team speak more directly to the public, and keeping within the bounds of what I can say with certainty, here are my current key briefing points to the AHPPC:
1. We will get through this as a society.
2. Lockdown has a different purpose depending on your end-game strategy. In New Zealand it is the main tool to try and eliminate circulating COVID. In the UK, Italy, Spain, and the USA, it is about throwing the parachute out the back of the fast-moving epidemic car to slow things down.
3. If Australia elects to ride the epidemic out, that is, flattening the curve to achieve herd immunity over months, rather than keeping on squashing it as now, we:
a. May need to loosen social distancing initially to get the daily cases up, but then tighten controls aggressively a month or so later. Why? You have seen the videos of bush fires ferociously speeding up hills to townships during the peak heat, wind and fuel conditions.
As the epidemic curve goes up, it is the same – the math of exponential growth in a population of non-immune citizens.
b. Will need to protect (i.e. physically isolate) our elderly and people with chronic conditions. This not only reduces ICU demand but could reduce deaths by up to 75 per cent.
4. We need economists, ethicists and philosophers. Where are the estimates of the total cost to society for different scenarios of managing this pandemic? Has anyone factored in the reverse effect of high unemployment rates, precarious housing and a protracted economic recession on health? Does the public know that 20,000 Australians die every year from the tobacco epidemic vs how many could die in this one?
We need open discussions about how we trade off saving lives versus societal and economic imperatives.
All of the above reflects on the need for us to balance math, equity, cost and risk – including political risk.
This requires exquisite leadership. And society must have transparent and open access to good information to participate in these major decisions that affect us all.
A version of this article first appeared in the Australian Financial Review.
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