The dynamics of disease
Professor Tony Blakely, an epidemiologist and public health specialist, discusses the details behind COVID-19 infection control models and exit strategies
CHRIS HATZIS
Eavesdrop on Experts, a podcast about stories of inspiration and insights. It’s where expert types obsess, confess and profess. I’m Chris Hatzis, let’s eavesdrop on experts changing the world - one lecture, one experiment, one interview at a time.
Epidemiology gives us insights into the population dynamics of disease. Tony Blakely is an epidemiologist and public health medicine specialist and Director of the Population Interventions Unit within the Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, at the University of Melbourne. Whilst principally an epidemiologist, he uses and combines methods from multiple disciplines: biostatistics, economics, econometrics and computer and data science.
Dr Andi Horvath sat down with Tony Blakely to discuss the nuances, complexities and impact of various models of COVID-19 infection control, and the way it currently influences decision making for governments and individuals.
ANDI HORVATH
Now, Professor Tony, how do you describe what epidemiologists do? What do you tell people at barbecues?
TONY BLAKELY
Well, I break it down and say epidemic -ology, -ology equals study, we are the study of epidemics, epidemiology. That’s how our profession began, with infectious diseases. So if we go back to classic examples, like John Snow and taking the pump handle off to stop cholera, it was a study of infectious disease epidemiology.
This is a fundamental history point for epidemiologists. It’s the Broad Street pump, which you can still go and see in London, which John Snow takes the credit for - it’s a slightly exaggerated story these days - of taking the pump handle off to stop the cholera epidemic. How did he do that? Why did he do that? He basically looked to see where the cases of cholera were appearing, which were seemingly random, until carefully he deduced that the cases of cholera were occurring in the houses serviced by one of the two providers of fresh water. Well, it wasn’t fresh water, but water to houses and not the other provider. It just so happened those providers were really mixed up. It wasn't just one block. There were different houses in the same block for different providers. So that’s the Broad Street pump story and how that type of investigation, which we would now call infectious disease or field epidemiology, led to a policy intervention, which was taking the pump handle off that then saved lots of lives.
These days, pre COVID-19 at least, the vast majority of us are looking at longer run epidemics like obesity or tobacco, cancer, heart disease, but it’s still the same idea. It’s looking at the causes of and the distribution of the tumours of disease and poor health.
ANDI HORVATH
So are epidemiologists essentially maths and stats people with a dollop of philosophy and ethics?
TONY BLAKELY
That’s some of the combination. There’s actually a lot that comes together. In my experience, you don’t have to be a good statistician to be a good epidemiologist. A lot of people equate those two together. I’ve seen many good statisticians who are not very good at epidemiology and vice versa. Epidemiology is about the logic and the way that you approach the problem solving. It’s not necessarily the stats. A good epidemiologist, in my view, will have pretty good content knowledge about the diseases or the risk factors or processes they’re studying. They’re not just a mechanic, if you like. They’ll have some training in public health generally as well.
Then there’s all sorts of flavours of epidemiology these days. There’s epidemiology that looks at genetic determinants of health, so genetic epidemiology. There are people who spend their whole lives just looking at air pollution and urban environments and what that means for health. So it is a very varied discipline.
ANDI HORVATH
Where is the frontline of epidemiology? Is it where GPs are reporting an anomaly? How did we know when COVID-19 came to Australia?
TONY BLAKELY
Okay, so there’s two questions in there. There’s where is the frontline and how do we know when COVID-19 got to Australia? They’re interrelated, but they’re not the same. Pre-COVID or putting COVID aside a little bit, the frontline is all over the place. We have cancer registries, we have surveillance systems, we have epidemiologists working with lab top scientists looking at genetic and molecular mechanisms. So where we take our ideas from, where we take our hypotheses to test is from all sorts of frontline, but the epidemiology that everybody knows about at the moment with COVID-19 is a little different and a little bit more traditional in a way. It does come from those surveillance systems for identifying new cases of infectious disease. We don’t know it’s an infectious disease person right from the get-go. It’s more like somebody has been reported with symptoms that look a little bit like something like influenza or maybe even COVID-19.
That comes through central surveillance systems. So, for example, in the country that I came from recently, New Zealand, which I know a little bit better on this front, we have a system run by an agency funded by the New Zealand government that does what we call EpiSurv, it’s called, epidemiological surveillance, EpiSurv, which basically has a system where GPs record any time they see a case that looks a little bit like it might be tuberculosis or hepatitis B or whatever it is. It all gets recorded and pulled in. That’s okay for the majority of things, but for something like COVID-19, you need much faster and more rapid type of surveillance systems, which we’re building at the moment to deal with the progress of the epidemic or just trying to stall the progress of the epidemic.
ANDI HORVATH
So it comes from a number of fronts. Where does it go centrally where someone says hang on, there’s a pattern here?
TONY BLAKELY
Okay, so assuming we’re talking about COVID-19 again. In Australia, that can be done at the state level or federal level or a bit of both. It really does depend on how you design your surveillance system. Let’s break it away from COVID and let’s think about cancer because that’s where we have cancer registries in all states and territories in Australia. That works by, for example, each time the pathologist, so that’s the person looking at the tissue samples taken out of a specimen at an operation or biopsy, and they see something that’s cancer, they are obliged to report it to the cancer registry, a clinician, usually a specialist, not a GP, in this instance because most people on confirmation of cancer diagnosis will be seeing a specialist, will be obliged to report or notify when they make a clinical diagnosis of somebody having likely lung cancer. So, for example, the respiratory clinician who does the bronchoscopy, that’s putting a tube down into somebody’s lungs and taking a tissue sample, that tissue sample will also go to the pathologist, but also they would be required to notify of a potential cancer registration.
So back to COVID-19, it depends on the type of systems we have in place. I’m not entirely sure of those systems in Australia because I’m a little bit more familiar with the New Zealand system.
ANDI HORVATH
Yeah, thanks for that, because after all, discovering the first cluster of patients is critical to any epidemic and therefore pandemic.
TONY BLAKELY
Yes, because that’s your first introduced case or cases, which can then propagate as an epidemic. Let’s think about this prospectively, going forward from where we are now. We actually need a really good surveillance system that will spot people getting the disease popping up, so little outbreaks occurring in a suburb in West Sydney or South Melbourne or wherever it is. Actually having the ability to detect those cases is critical to then doing very fast contact tracing, so you find the people that person’s contacted, both previously and since they became symptomatic. Then you chase those contacts of the contacts to try and find all the people that may have got the infection. Supplementing that is extremely - or we hope will be extremely good testing, whereby there’s rapid testing of people to see if they actually have the virus on board or not. That type of surveillance system going forward is critical.
ANDI HORVATH
Now, I want to come back to COVID-19 because what you’ve just described, isn’t that what you call the tracking model, where you’re tracking by looking at and testing who has the disease and tracking who they’ve been in contact with?
TONY BLAKELY
Yeah. We call that contact tracing. So there’s a number of functions that are happening simultaneously and they overlap a little bit. So, for example, somebody who is infected, they are isolated and then we trace all their contacts. Amongst those contacts, we test their contacts to see if they actually have COVID-19 as well. If they have COVID-19 as well, they are then isolated, case isolation. You just keep going out and out on that contact tracing until you’ve gone to a point in time with the contacts you’re finding are four months ago. There’s no way they’ll have COVID-19. It’ll be those within a few days of the index case presentation. That’s the contact tracing and the identifying of active cases to isolate.
But then there will also be those people that contacted the current case that we consider that their exposure to the current case was big enough, severe enough, whatever term you want to say, that even though they’re not testing positive for COVID-19 at the moment, we’re going to quarantine them because we’re concerned they’re going to develop it. So the people who are close contacts of the case, even if they’re not a case yet, will be quarantined for two weeks to allow enough time to pass before we can confidently say they were never going to get the disease from this particular contact. So there’s distinctions there, contact tracing, case isolation for those who are actually actively infected, and quarantine of those contacts of the actual cases that we’re worried may be yet to develop the disease.
ANDI HORVATH
Professor, I’d like to hear your thoughts on the current app that Scott Morrison is suggesting be used in Australia in a voluntary sense. Jacinda Ardern in New Zealand is suggesting that people also do a diary of who they’ve been in contact with. Do you think that’ll work?
TONY BLAKELY
Okay, so let’s just pull back to the principle here. The principle is being able to do the contact tracing as accurately and as quickly as possible. That’s why we’re talking about things like apps. The apps, if somebody’s got it on and is connecting through Bluetooth to other people’s phones, allows that to be done so much faster. It saves a huge amount of human resource. That is the public health officers who are out there doing the contact tracing. That saves them masses of time. So do I think an app is important? Absolutely. I want to pull back a little bit more because I think one can understand these things much better if you understand the principles of what’s happening.
Now, what’s happening here is we are dealing with a disease which has a high case fatality rate and we therefore don't really, unless we really have to, let it wash through society until we get to community or herd immunity. It’s just too unpleasant. The flipside is that we may not be able to achieve elimination, although that question remains open. What we also want to do - this is an optimisation problem - we also want to live in a society that allows us to move around more freely and for our economy to function a bit more normally and for us to get back to normal, basically.
Now, we would not be able to loosen up our restrictions now that much if we don’t have vastly improved surveillance and contact tracing and testing. Why is that? Because when we loosen up, we’ll get back up to that reproductive rate. People call it the effective reproductive rate. It needs to stay beneath one, so each person who’s infected only passes it onto just less than one or fewer people. That’s the goal here.
The thing here is the contact tracing, by being able to be done faster, means that cases are found quicker and therefore those cases will pass it onto fewer people, which lowers the reproductive rate, the effective reproductive rate. The testing’s the same. The quicker you have that testing, the more comprehensive you have that testing, the more people who are infected you take out of society quicker. So that works as a beautiful seesaw. Think of those two things on one side of the seesaw. That faster contact tracing through apps and the better testing to know who is carrying it and who isn’t means that you can put your emphasis on that and at the same time loosen up society more because you’ve got this countervailing influence. That’s why they’re so important. That’s what we think, and we’ve got a very good reason, theoretically, to expect that to be the case. Obviously we’re in virgin territory here, testing all sorts of new things the world hasn’t done before, but there's very good reason to believe that that much better, wider, deeper testing and the faster, more accurate contact tracing will mean that we can get out and go back to school, go back to university, go back to work and still keep this epidemic under control.
ANDI HORVATH
So that’s your preferred model that Australia could implement right now - we balance the, I guess, civil freedom to function in society, but also keep people safe and not jeopardise our health system and the elderly.
TONY BLAKELY
Okay, so what I was talking about there was the way to do that particular option. Pull back even further now, we have three exit strategies out of this COVID epidemic. One, we eliminate, we lock our borders and we hunker down until the vaccine arrives. That is actually getting more consideration now than it was 10 days ago in Australia. I believe it’s a live option. The second strategy is the one I was just talking about, which people call suppression. Increasingly, myself and other academics providing advice to the government are calling it controlled adaptation because you really are adapting. That’s the second option. The third option is you say, let’s just get this over and done with. We’ll protect our elderly, we’ll protect those with comorbidities, we’ll get the best treatments possible, but we’re going to let this infection wash through society until such time we get to a number of people being infected that they’re therefore immune that we have this thing called herd immunity. Three options, elimination, suppression or herd immunity.
What we were just talking about with the apps, contact tracing, testing, that will be critical for elimination to ensure it’s successful and guard against outbreak and critical for the suppression to mean that we can actually pull it off with as much liberalisation as we possibly can without the epidemic taking off on us. So am I recommending any of those three options? No. My job as an epidemiologist is to provide advice as best as I can, because I think this is a decision beyond what one epidemiologist or the epidemiological community can make. There are different pros and cons of each of those three strategies. I think it’s most likely Australia’s going for the suppression route, which would mean that those apps and the contact tracing is so critical. But the good thing about going for suppression or what we’re increasingly calling controlled adaptation is you can pivot.
So in a week’s time, if your numbers are still really low and we think, gosh, we could give elimination a go, we can pivot to try elimination hard for four weeks and see how we go. If we really think that’s not on, we can stay in the holding position of suppression or controlled adaptation. Or if we find much better treatments for people who have got serious illness, we can pivot towards letting the infection wash through society a bit more and develop that herd immunity, which would be essential if, heaven forbid, but it’s possible, we never get a vaccine. So these are all the things we need to weigh up at this point in time.
ANDI HORVATH
That’s an interesting point, if we never get a vaccine, because just from looking at what’s happening in America, which appears to be that wash-over model of herd immunity, that’s going to lose a lot of lives. I would have thought, ethically, we’re actually endangering a lot of the vulnerable in our community. That to me, just philosophically, seems rather strange. So why would some countries go towards the herd immunity as opposed to, say, elimination like in New Zealand?
TONY BLAKELY
Okay. There's a number of questions in there. Let’s deal with the elimination first. There’s only a few countries in the world that have the privilege of even considering elimination, New Zealand, Australia, perhaps a few Pacific islands, maybe Iceland, basically island countries that don’t have land borders. China can’t eliminate. They’ve got land borders. They’re always going to be in that game. The second question I picked up in there, Andi, was about the ethics of allowing the epidemic to wash through for herd immunity. I’m going to actually offer a slightly contrary and perhaps shocking perspective on this because I think we have lost perspective.
In Australia, if the epidemic was just let to rip, which nobody is going to do - I’m not advocating that. I made that very clear - but if it was left just to rip, from what we know so far - and the data is not that great - but we think that that would result in about 130,000 deaths. Those deaths would be largely concentrated amongst the elderly and people with comorbidities. So the first thing you do at that point, you say, well, okay, let’s really protect our elderly and protect our people with comorbidities, because they could be protected to the point we only have 10 per cent or 20 per cent infection rates, but younger people have a higher infection rate to give you herd immunity. Bumph, you’re down to half as many deaths. You’re down to 60,000 or 70,000.
We’re also aware that they’re getting better treatments. Things like the old antiretroviral drugs are showing promise, as well as immunotherapy, where you take immunoglobulin or serum from a person who’s been infected and give it to somebody who’s got, currently, acute disease, those types of people. That will probably, in my estimation, half it again. Bumph, we're down to 30,000 to 40,000 deaths. Now, we’ve lost perspective here. Each year in Australia 20,000 people a year die from an epidemic that’s been going for 50 years. It’s called tobacco. Those people dying of tobacco tend to be younger and healthier than those people dying of COVID. So if you do the maths, actually there’s very little difference, probably, in the healthy life years lost due to tobacco year in year out compared to COVID. Now, I’m not advocating that we just therefore let the epidemic rip. I’m just pointing out that we have lost perspective on that simple piece of arithmetic, and it’s understandable that we’ve lost perspective because the thing about COVID is it happens so intensely and over such a short duration of time and as a society we’re appalled by the sight of body bags building up outside an ICU in an alley in New York. It is genuinely shocking, but my job as an epidemiologist is to point out these perspectives and just making that clear.
ANDI HORVATH
You raise a good point about tobacco-related or even alcohol-related and obesity-related diseases that do take people in large numbers, but can we really compare apples and oranges?
TONY BLAKELY
I think there's a slippery slope there you just started on…
ANDI HORVATH
Oh no [laughs].
TONY BLAKELY
...which goes as follows. This person’s dying of tobacco-related disease. They chose to smoke, that’s their fault. That’s the type of logic that you can get into here if one starts doing that blame game. We’re certainly not doing that with COVID. We’re not saying that person didn’t wear a mask. They picked up COVID. They’re to blame. I don’t think it’s appropriate to play the blame game for either of them because, frankly, COVID’s everywhere and tobacco is so highly addictive and there are heaps of reasons, socio-politically, culturally, economically why people get hooked and then have trouble getting off it. So I hear what you’re saying, but something like an infectious disease, that’s got that dread factor. That’s got that sense of it can strike anyone down. But at the end of the day, the numbers may not be too different with those caveats I gave of protecting elderly and comorbid people from the infection and the arrival of new treatments. So it may not be too different from tobacco.
But I also get - and I’m not trying to diminish this or belittle this - is that it is shocking to see that many happening in the course of two to four weeks in places like New York, initially, and it’s not something we want. But these are tough decisions to make.
ANDI HORVATH
Tony, how much is the economic component important in making the decisions for elimination, herd immunity wash-over or contact suppression?
TONY BLAKELY
Controlled adaptation. It’s critical. So I like - well, it’s not that I like to think about it anyway, but one useful way to think about this whole dilemma is we have an optimisation problem requiring an optimised solution. The three things that are sometimes going together but often conflicting are preventing the health consequences of COVID - and I’ll come back to the health consequences because it’s more than just COVID - whatever we do has to be within the capacity of our health services (2) so if we do have cases we can actually manage them and not have people not able to go to ICU because we don’t have enough beds. (3) the third objective that we’re trying to optimise, the societal and economic functioning so that people are not unemployed, or as least unemployed as we can achieve. Our job is to optimise those three repeating concerns, very difficult to do.
Now, just drilling down into the health only, one of these three objectives we’re looking to optimise, sight has been lost, although in the last couple of days we’re starting to hear more discussion, thankfully. But there’s COVID-19 direct health effects or disease effects or death effects, but there’s all the indirect effects that I suspect, at this point in time, are much greater than the direct COVID effects. So, for example, when a health system reprioritises or repurposes its hospitals to have higher ICU beds, to clear it out so that you can deal with an epidemic should it take off, there are people who are not getting their hip replaced. There are people who are not going to the coronary care unit because they thought, aah, I’m not sure about this chest pain. I think I’ll just stay at home, and the guys at the hospital is busy, that sort of thing. These are displacement effects within the health arena or objective alone whereby we may have more deleterious health impacts of this epidemics with those effects than the direct COVID-19 effects. So it is quite a challenging thing to weight up.
One extra thing I’d like to say at this point is that I’ve been liaising a lot with economists on this issue in the last week or two and they do make the following point very clearly, that their view is that economic salvation or the economic improvement after this really does require getting on top of COVID. They’re not advocating let it rip or some form of rapid approach to herd immunity yet because they see getting it under control or eliminating it is vital to being able to have economic success after that. So everything I’ve just said, they’re competing objectives, but they also change over time and with each strategy. It’s like a really complex jigsaw puzzle to solve this and there’s not only one solution. Each country is taking different pathways out of this. Which one will be better, we’ll have to wait and see. A lot of which one’s going to be better is going to depend on things we simply do not know yet, like when and if there’ll be a vaccine.
ANDI HORVATH
Can you first define for us the difference between elimination and eradication?
TONY BLAKELY
That’s actually quite simple. Good [laughs]. Elimination is where you get rid of it from one country, eradication is where you get rid of it from the whole world. So people have been very careful to differentiate that because when people talk about eradication, they’re implying global eradication, which simply is not possible. That reminds you that when you achieve elimination, you’ve still got every other country around you with the virus circulating and you’re not safe because of potential cross-border incursion.
ANDI HORVATH
Tony, do you have a perspective on what’s going on in the US? We’re seeing various states trying to liberate themselves, moving towards a wash-over model.
TONY BLAKELY
Right, so we have variety around the world in how countries have or have not responded to COVID-19. The countries that have had the worst impacts so far, the Spains, the Italys the UKs, the USAs, are those where just the epidemic got a little bit out of control and got up a head of steam. In all those countries, they’re not having enough infection to wash through to herd immunity. So, for example, in the US, with the current experience, they’re probably heading towards 2.5 per cent of the population being infected by the time they get it back under control. So what they’re doing is not achieving herd immunity through this approach. It’s more that it just got out of control in that early phase and wasn’t successfully suppressed.
When they do get through that, they will be back in the same place as Australia is right now, whereby they’re in that controlled adaptation or suppression phase. They will also need to keep doing that until such a time as there is a vaccine or we get better treatments and we decide to slowly let some people in the population get infected to achieve herd immunity. They’ll be right back with us because over 90 per cent of the population would not have been infected. I’m saying that as I’m absolutely sure [laughs].
The thing about COVID-19 is that we are not sure about everything at all. So, for example, each person who’s infected with COVID-19, we believe there’s about one other person who’s asymptomatic. If that ratio turns out to be higher, for example, five asymptomatics for every case that we find, it actually - places like the UK and the US will have higher infection rates than what we think they’re having currently, which does mean they’re starting to move towards herd immunity, which would be an advantage to them, perversely enough, if in two years’ time it appears we’re just not going to get a vaccine for another three years and countries need to get to having that immunity and that resilience by allowing natural infection to pass through.
ANDI HORVATH
You’ve certainly outlined a complex picture for us. Do epidemiologists get asked to look into the crystal ball based on what they know of history?
TONY BLAKELY
Well, let’s deal with the crystal ball, which is going forwards, and let me use a way that I describe my normal day job. So just to back up a little bit here, I’m actually not an infectious disease epidemiologist. I have colleagues who do that. I understand the principles of it, I had training in it, but it’s not my day job. My day job is to model the effect of interventions on the population’s health, and normally through things like smoking tobacco, cancers, heart disease, those non-communicable diseases and risk factors. The way that I describe that is that sometimes I look in the rear vision mirror of the car and sometimes I look out the front window. When I’m looking in the rear vision mirror I’m using data collected in the last 10 or 20 years and I’m learning from that analysis. That’s what most epidemiology is, looking at observational data collected in the past. We assume the associations we see in that will apply to the future.
The other part of my day job is I look out the front window and I actually forecast the future, like a long-range weather forecast, under business as usual. Then I layer an intervention over that, like a tax on sugary drinks or a colorectal cancer screening program or a dietary intervention for people who are overweight. Then we estimate the health gains and all that sort of stuff going forward and report back to our academic and our policy end users as to what we think and which interventions appear to have a big impact, versus a small impact, and which are cost effective. Some might even save money to the health system. That’s what I normally do.
What’s happened here with COVID-19 is that particular skillset to think up and above just an infectious disease and consider the payoffs with chronic disease and economic inputs and stuff is quite valuable for being able to work your way through and make predictions about what’s going to happen with some sense of confidence, low, medium, high probability. So that’s why I’ve come to be speaking a lot about COVID-19, because of that ability that I have with leading this other research program.
ANDI HORVATH
Who has the ear of the government and is there debate among epidemiologists?
TONY BLAKELY
There is a special mechanism through their policy advisory committees and through their chief medical officers and deputy chief medical officers. I actually think that has worked pretty well. I’d give the Australian system seven or even eight out of 10 in how that’s worked. There have been moments where they haven’t abided by the first principle of the pandemic plan that was prepared just in October last year, as it happens, of openness and transparency on some of the modelling stuff. But that’s been sorted out in the last week or so, so that's pretty good. Now, beyond that, we live in a civil society, a democracy, and so what academics say and what they put out and things like The Conversation or opinions in the Sydney Morning Herald we assume is also getting picked up as being a moment in time where we don’t exactly know what’s happening. So the wide range of opinions and seeing where there’s consensus and also being able to have debates in public has been essential for helping us move forward.
I know, myself, personally, my understanding of what’s happening here is a long way from where it was two to three weeks ago. That’s in part because of engaging in this debate and sharing these ideas and debating them with colleagues. So is there consensus amongst the epidemiological community? No. Most of the epidemiologists I know are probably a bit more in my camp where we’re saying there’s actually multiple ways out of this and it’s not clear which is the right one. Our job is to provide you with the pros and cons of each option and help you weigh up those decisions because it’s not our decision alone as epidemiologists. At the end of the day, what we do, we provide the best advice possible for society to make its decision, and in this case largely through the apparatus of state and federal government.
ANDI HORVATH
Professor Tony Blakely, thank you very much.
TONY BLAKELY
My pleasure.
CHRIS HATZIS
Thank you to Tony Blakely, epidemiologist and public health medicine specialist and Director of the Population Interventions Unit at the Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne. And thanks to our reporter Dr Andi Horvath.
Eavesdrop on Experts - stories of inspiration and insights - was made possible by the University of Melbourne. This episode was recorded on April 20, 2020. You’ll find a full transcript on the Pursuit website. Production, audio engineering and editing by me, Chris Hatzis. Co-production - Silvi Vann-Wall and Dr Andi Horvath. Eavesdrop on Experts is licensed under Creative Commons, Copyright 2020, The University of Melbourne. If you enjoyed this episode, review us on Apple Podcasts and check out the rest of the Eavesdrop episodes in our archive. I’m Chris Hatzis. Join us again next time for another Eavesdrop on Experts.
“Our profession began with infectious diseases,” says Professor Tony Blakely.
“So, if I break it down and say epidemic and -ology, which equals study, we are the study of epidemics – epidemiology,” he says.
“My day job is to model the effect of interventions on the population’s health.
“Sometimes I look in the rear vision mirror of the car and sometimes I look out the front window and I actually forecast the future, under business as usual. Then I layer an intervention over that, like a tax on sugary drinks or a colorectal cancer screening program.
“Then we estimate the health gains (from those interventions) and report back to our academic and policy end users on which interventions appear to have a big impact, versus a small impact, and which are cost effective.”
Professor Blakely explains that this particular skillset also applies to modelling COVID-19 infection control and exit strategy models.
“We have three exit strategies out of this COVID epidemic. One, we eliminate, we lock our borders and we hunker down until a vaccine arrives. The second strategy is the one people call suppression or controlled adaptation because you really are adapting,” he says.
“The third option is we’ll protect our elderly, we’ll protect those with co-morbidities, we’ll get the best treatments possible, but we’re going to let this infection wash through society until such time we get to a number of people being infected that they’re therefore immune - we have what we call herd immunity.
“There are different pros and cons of each of those three strategies.”
Episode recorded: April 20, 2020.
Interviewer: Dr Andi Horvath.
Producer, audio engineer and editor: Chris Hatzis.
Co-production: Silvi Vann-Wall and Dr Andi Horvath.
Banner: Getty Images