Contain This: The Latest in Global Health Security

“We’re trying to stop people getting sick”: A conversation about preventing, containing and treating a pandemic with infectious disease specialist and an epidemiologist, Professor Allen Cheng

April 19, 2022 Indo-Pacific Centre for Health Security: Department of Foreign Affairs and Trade Season 2 Episode 20
Contain This: The Latest in Global Health Security
“We’re trying to stop people getting sick”: A conversation about preventing, containing and treating a pandemic with infectious disease specialist and an epidemiologist, Professor Allen Cheng
Show Notes Transcript

Today’s episode features Professor Allen Cheng, the Director of the Infection Prevention and Healthcare Epidemiology unit at Alfred Health, Professor of Infectious Diseases Epidemiology at Monash University and the Chair of the Advisory Committee on Vaccines to the Therapeutic Goods Administration and an infectious diseases physician. 

He is also known to many for his year-long secondment as the Deputy Chief Health Officer of Victoria from July 2020 – June 2021. As Professor Cheng says in today’s episode, he has a “very specific skill set.” An infectious diseases clinician specialising in respiratory infections and flu vaccine effectiveness, he was expertly qualified to lead Victoria’s public health response to the COVID-19 pandemic. 

Professor Cheng talks about the challenges of transitioning from a researcher and clinician to public health practitioner, and the lessons he learnt in the process. He advocates for innovative approaches to public health preparedness, like a “public health reservist core,” and talks about how governments can and should effectively buy and use vaccines and COVID treatments. 

It’s a fascinating discussion and we hope you join the conversation @CentreHealthSec

Dr Stephanie Williams  0:01

Hello, and welcome to Contain This. I'm joined by infectious disease specialist and epidemiologist Professor Allen Cheng. Professor Cheng is a man of many responsibilities. He is currently the Director of Infection Prevention and Healthcare Epidemiology Unit at Alfred Health, a Professor of Infectious Diseases Epidemiology at Monash University, the Chair of the Advisory Committee on Vaccines to the Therapeutic Goods Administration, and an infectious diseases physician. He is also Vice President of the Australasian Society for Infectious Diseases, and was a member of the Advisory Committee on Prescription Medicines and Co-chair of the Australian Technical Group on Immunisation amongst numerous other committees and boards. 

But many of you will know him from his year long secondment as Deputy Chief Health Officer of Victoria from July 2020 to June 2021. As Professor Cheng says in today's episode, he has a very specific skill set – an infectious diseases clinician specialising in respiratory infections and flu vaccine effectiveness, he was expertly qualified to contribute to Victoria's public health response to COVID-19. However, as he notes, the transition from researcher and clinician to public health practitioner and expert came with its own set of challenges and lessons that shaped Professor Cheng’s view on the ongoing response to the pandemic. 

It's a fascinating discussion that covers how we could better respond to public health emergencies, and how Australia and importantly, its neighbours in the Indo-Pacific can continue to get ahead with the rest of the COVID pandemic.

Allen, thanks for joining us today. 

Prof Allen Cheng  1:43

Thanks, Steph. 

Dr Stephanie Williams  1:43

I want to start by just getting some of your reflections on the role that you have played wearing so many different hats through the Australian pandemic response. I think at one point you have been on the Advisory Committee on Vaccines to the TGA, to ATAGI, now a household name, but Australian Technical Advisory Group on Immunisation, as well as the group advising the government on what to buy for vaccines very early on, and Deputy Chief Health Officer of Victoria. As well as a day job as a clinician. Just looking back over those last 18 months, I'm interested in your reflections about the different roles and lessons you learnt along the way?

Prof Allen Cheng  2:30

Yeah, look, it's been a fairly wild ride, I have to say. I think between, you know, three committees, I think it was ATAGI, HPPC and CDNA, I think it's like a thousand meetings and two years or something that I've been to, and there's probably a few more, you know, all the ad hoc ones that you have on top of those. So, yes, it's been a fairly busy couple of years. I think I've described myself - I was joking with someone else's, what's that, what's that movie where he guy says, you know, "I'm a person with a very specific set of skills." And I'd that's what I would describe myself, as you know, I've said, you know, I, in my research, interest has been in, you know, respiratory infections and flu vaccine effectiveness specifically, and then I happen to be on some of these committees, and I was on these committees before COVID, obviously, and then in the hospital condition, and we deal with flu outbreaks in the hospital. And I've done some mathematical modelling in the past, and I've done tropical medicine, and so on. So I have do have very specific set of skills that are quite helpful for, for, you know, new respiratory infection. And it's not entirely by accident. So these are things that I thought were important skills to have. But hopefully, they are useful for the country to have at the time like this.

Dr Stephanie Williams  3:43

I think we've all benefited from your very specific set of skills as you describe it. What about as a clinician moving in between clinical work and advisory work to the Deputy Chief Health Officer role? If thinking about public health audience and practitioners, what were some of your standout takeaways about working in the health department?

Prof Allen Cheng  4:07

Yeah, look, I mean, it's a clearly very different job. So, you know, when with clinicians deal with individual people, and when you, you know, public health, as Chief Health Officer that's dealing with the population and the powers that you have, as the Chief Health Officer, at least in Victoria, you know, they're sort of spelled out by legislation. And, you know, there's a very specific role for the Chief Health Officer signing directions, and at that time, and so on. So they are very different in some ways. 

But on another level, they aren't quite as different as you might think. So you know, in a hospital, you have to explain things clearly to your patients, and, you know, your patients might be very well educated, you might be talking to, you know, a patient, who happens to be a doctor, or health professional, or you might be talking to someone that may not have English as their first language, or have might have different health beliefs. And so that's not, you know, unlike the public, really, when you're talking to them. So you're trying to explain things concisely, and simply is, is an important skill for clinicians and, obviously, is very important in communicating with the public.  

But that said, you know, it's a very different environment, particularly when there's a political overlay. And this is a, you know, COVID is a very political story, the way that journalists approach that is very different to how you would go when you're talking to a patient, for example.  So yeah, it was pretty confronting for someone that's not really used to the spotlight and public speaking is not my, is not my forte, but I hope that, you know, I sort of brought enough technical knowledge to it and explained it as best I could. There was some I think there was some odd times I remember trying to explain how a PCR works, I think it was in the context of, you know, why do we get false positive PCRs or something like that. And I've got about halfway through and then I realised all the journalists were sort of looking at their phones, and they'd all tuned out. So I'm not entirely sure if that was the most successful explanation, but hopefully, other ones were a bit better than that.

Dr Stephanie Williams  6:16

I think it was terrific to see you in action. And it gives one pause for thought about how we think about the public health workforce, which we know is thin and stretched in many countries and in Australia hasn't had necessarily the amount of growth that it needed for the pandemic, you know, pre-pandemic, and thinking a bit more flexibly about drawing in clinicians into public health work as a as a workforce, I think your experience this demonstrates that.

Prof Allen Cheng  6:44

Yeah, absolutely. In fact, before the pandemic, I'd actually I think I've been sort of selling this idea that we need like, like the equivalent of an Army Reserve, you know, a you know, there's a lot a lot of clinicians and particularly infection control nurses are very highly skilled and you know, they know how, you know, they understand disease transmission, they, you know, understand lots of, you know concepts about infectious diseases that are quite important, and that they're like the perfect expert workforce to sort of help in public health and if you know them and, you know, practice practitioners and infectious diseases physicians with an interest in public health, just had a little bit of training and a little bit of orientation into how government works, or you know, how things happen, and then I reckon they'd make a really good reserve workforce. 

Dr Stephanie Williams  7:33

Yes, it's a good idea. 

Prof Allen Cheng  7:34

In Victoria, particularly, I think most of the health department now is infectious diseases physicians.

Dr Stephanie Williams  7:39

Yes. Can I switch now to some questions on COVID vaccination. As a world and as a country, and certainly for Australia, in the region, we've all been working towards the targets of 70% population coverage by country by 2022. And as we have embarked on this global COVID vaccine campaign, we have done so thinking about primary series vaccination, we've turned on boosters in response to or in anticipation of an Omicron wave. And now we're seeing that immunity may not be as long lasting as we, well we're learning about immunity to COVID as we go. There are different ways COVID as the disease and the epidemiology can play out, and vaccination is one part of the response to that. But I wonder if you can just help us think through the ways in which vaccination programmes for COVID might look like in one to three years? Are they going to be for everyone every year? I'm just interested in some of your observations about the trajectories we could be on for vaccination in the near term.

Prof Allen Cheng  8:54

Yeah, look, it's it is difficult to know and a key unknown is sort of what is the driver of the new variants, and for new variants, firstly, are they you know, are they more severe, and how much did they evade the current vaccines. And so a big question is about whether we need variant vaccines and whether they work. They're actually some early indications, at least for Omicron, that a variant vaccine actually may not be much better than just giving the same dose of the existing vaccine. It's monkey experiments. It's all pretty early stage at the moment. But that's sort of a concept that's familiar to immunologist from flu, that sometimes when you give another vaccine, you're just, you know, boosting the existing cells and the existing antibodies rather than creating new types of antibodies. So that just goes to say that it is going to be fairly complicated going forwards. I think there probably is and needs to be a little bit of thinking about what it is that we're trying to do. And really, we're not trying to stop transmission. In that the aim is to stop people getting sick. And stopping transmission can be one way of doing that. But vaccinating people themselves, obviously, it's another way of that. And treatments are another method of that. And now that in a lot of countries, most people have probably been exposed to, to COVID, or to SARS2 at some level, perhaps we might need to step back and say, well, actually, who are we trying to give protection to now with the tools that we have, and what are the best ways to do that?  I think, in general, vaccination is a it's cheap, it's one off, or at least less frequent than much less expensive than treatment, and prevention is generally better than cure, but where most people have got infection, we just need to think a little bit about, you know, who is it that still needs to be vaccinated.  And in terms of, you know, are we going to have an annual vaccination, they're going to be flu type vaccines with multivirulent strains, we don't really know at this stage and WHO has set up a committee and I think, Raina MacIntyre and Kanta Subbarao are on on that committee, to really look at that question about, you know, do we need a flu type vaccine and obviously, the vaccine manufacturers are also well down the track in terms of developing those sorts of vaccines. I don't think they're technically difficult to make, but, you know, what is the strategy I think is important. And then how do we keep an eye on new variants. We're, you know, we're coming off the end of an Omicron outbreak, but, you know, we're up to that letter in the Greek alphabet. So you know, there are going to be more and anything that is going to spread must have an edge on whatever we've had, so that probably does mean it's going to be, going to evade immune system responses to some extent.

Dr Stephanie Williams  12:03

So then in very practical terms, if, if what we're seeing in the in the graphs of waning immunity, if you have been boosted in what are we now, March 2022. And your antibody levels to measurable levels decline, as we have seen the studies to date. By the end of this year, what does that mean for population protection in terms of, should there be another wave? Are we talking about vaccines, not only thinking about protecting the most vulnerable from disease, as you have said, but using them on and off for outbreak response?

Prof Allen Cheng  12:47

Yeah, so so they're basically sort of three main drivers of what might come next. So that's basically a new variant coming along. And so that can happen at any time can happen in the summer, can happen whenever. Then there's, there's waning immunity. So as the protection from either your last infection, or your last booster wears off, then you become relatively more susceptible, although you're more susceptible to infection, but you're still reasonably protected against severe disease, so that's something to keep in mind. And then whether particularly in temperate areas, whether they're seasonal patterns. So flu is seasonal, in the tropics, but in a sort of different way. But there may be some seasonal drivers. And we actually don't really know that at the moment, despite having a couple of years of this, there's just not enough data sets to know, to what degree seasonal factors are important.  So if we can start to predict, you know, for example, you know, if it's flu, that that's probably the archetypical, we know that every year there's going to be a flu season at some point, except maybe the last couple of years. But in general, there's a winter outbreak in the temperate region, tropics, that's, you know, by seasonal. And then that's when we would deploy the vaccine to try and predict what is the next strain that's coming along, and then what is the when is the time that that's going to come, and then how long does it have to protect you for. So we give it, you know, we try and give the flu, the flu vaccine and sort of, you know, just before winter to try and get the most protection to those that are most at risk over the winter season. Now, with with COVID, we don't know that the seasonal we don't know what's coming next. But that's sort of what we need to get to a point to, and then then we're basically treating it like influenza. And I suspect that eventually that's sort of where it's going to go.  Could we have better vaccines? Could we have, you know, again, at the multi-valent vaccines, like the flu with lots of different strains in them? Or can we have a better vaccine that just, you know, works against all of them that are that, you know, they all still to come? We don't know, obviously, a lot of people working on those, but we don't have those yet.

Dr Stephanie Williams  15:00

So my last question on vaccines then, if you imagine that you are a health minister of a middle income country, you have purchased vaccines to cover your whole population, or the eligible population for 2021 and 2022, and you're thinking about a health budget and buying vaccines over the next couple of years. Would you be putting aside enough money for everyone again, just in case or putting aside for a fraction? It's a very literal question, but respond to it how you wish. 

Prof Allen Cheng  15:36

I understand that, yeah, health ministers do have to make these tough decisions and there are opportunity costs of all of those I'm sure as well, and especially in low and middle income countries. I mean, I think it will, who we will want to vaccinate, and possibly more than once, give more than one boosters are probably people with risk factors and that means older people. And, you know, for better or for worse in in lower and middle income countries that actually is a relatively small part of population compared to Australia, for example. So and then there's the second sort of big group would be the healthcare workforce. And then after that, I would start thinking about, you know, critical workforces who, you know, who's going to be important, the military, the police, you know, who else, distribution chains and those sorts of things as trying to keep people safe. But in general, you know, younger people don't get severely unwell if they've had a particularly if they've had a dose or two vaccine on board. So, if I was budgeting for it, I would be thinking about, well, you know, who are the risk groups that I might need to keep giving vaccines to, and then for the others, you know, wait to see what happens in terms of the protection from vaccines against severe disease, which I think is sort of the most important part of it.

Dr Stephanie Williams  16:56

So can I switch now to treatments. And we know that WHO is considering some of the oral antivirals for recommendations which they have been doing through their living guidelines. We know some of these oral antivirals have already received authorization from the TGA in Australia and the FDA in the U.S. Can you talk through how you are thinking as a clinician, and as a public health person about the place that treatments have in a COVID, a package of COVID response commodities?

Prof Allen Cheng  17:32

Yeah, so as I think we mentioned at the beginning of this, you know, treatments are one tool that we have to reduce severe disease, and, you know, vaccines are one of those public health measures and preventing transmission in general is another way of doing that. But treatments are, you know, another way of doing that. But payments in general are never quite as good as they look on the box, because you have to get it to them, and usually with thin, a, you know, so for these antivirals within five days, to to be effective, and not everyone turns up on, you know, on the fifth day of their illness. So as from a public health point of view, they never quite work as well as, as you might hope.  But that said, as a clinician, you know, it is great to have something that you can offer a patient to make them better. And otherwise, you know, what you're left with as clinicians is, you know, just trying to support them through the illness while their body's doing all the work. And it's great to be able to offer something an antibiotic and antiviral to help treat the infection.  I think it's sort of it is difficult for antivirals, because there are a choice. And it's great to have a choice. And that's obviously that's obviously a very first world problem to have. But, you know, there's still a question, well, which one should we use. There's some, some of the intravenous, some intravenous over a couple of days, some of them have a lot of side effects or sort of drug interactions, and some of them kind of be used in certain groups, so molnupiravir can't be used in pregnant women, for example, because it may be teratogenic. So there are lots of these, you know, sometimes the decision is made for you. But we still don't know which one is best. 

And, and then on top of that is layered this, you know, there isn't an unlimited supply of these. And we do have quite a lot of cases of COVID. So who do we give it to and, you know, some of those decisions.  So that sort of goes to this problem that, you know, we have a supply coming in, we know that it is a safe and effective treatment for you know, for people that are defined by criteria, and then at the other end of the equation, there's clinicians who just want to give it to everyone. But then how do we use that supply responsibly? How does that programme work? 

We have that system where, you know, TGA will say, you know, this is a safe and effective vaccine, we have this tool in the toolbox, and then ATAGI and the vaccine taskforce in Australia will go and say, well, how do we want to use this tool? Who do we give it first to who do we, you know, how do we use it as boosters? How many boosters do we give? All these questions we can answer. And then the clinicians will have those discussions with individual people to say, you know, we're ATAGI is recommending this, do you want it or not, and answering those questions at the end. At the moment, for the treatments, we're missing that middle bit. We have the, you know, the regulation bit to say that this is a safe and effective treatment. We have the clinician saying, you know, being able to talk to to individual people, we have the task force, saying these are the criteria criteria by which it works.

Dr Stephanie Williams  20:43

And that challenge is just amplified in low income settings and middle income countries where you can see the interest and the importance of equity of access to treatments, especially if, and correct me if I've interpreted this wrong, one of the oral antivirals is said to reduce your risk of hospitalisation if given properly at the right time, etc, by 90% compared to the standard care or compared to no care, which, at the point of delivery in an unvaccinated person is a big, big risk reduction. But how you access and make those decisions and then deploy the medication safely in a system so that they work that missing, that middle bit is missing in so many places.

Prof Allen Cheng  21:39

Yeah, so that. So that's a really important point, because the trials excluded people that were vaccinated, basically. So we don't know if it works in vaccinated people, we would assume that if you get infected, having been vaccinated, your risk of becoming hospitalised hospitalised is less and but it won't be reduced further because this is a different mechanism, mechanism of action to to antibody therapies, for example, but is that actually true? We don't know that for sure, really.  And so, again, you know, if I was in a country where there was much more limited access to these treatments, would really be trying hard to work out, you know, who are the people that are coming into hospital, and then what other opportunities are there to reduce that. So if the people coming into hospital, you know, older people and people with diabetes, and so on, then they're probably the people that you want to be giving antivirals to, and then trying to make that the cleanest, you know, the smallest group that you can, so that, you know, the number needed to treat is the sort of most optimal to make use of those resources. But it is difficult, and there's not a lot of evidence to go on at the moment.

Dr Stephanie Williams  22:59

Can I switch tact and ask you about Australian experts and relationships and partnerships in the region. So I know that we have talked during the pandemic in different regional forums. But I'm interested in where you see the opportunities are for Australian health security experts or health experts and institutions to build stronger relationships in the Indo Pacific.

Prof Allen Cheng  23:25

Yeah, look, there's just so many different levels where these sort of exchanges happen that, you know, for example, at the TGA, I'm aware that they've got a whole work package supporting, you know, the regional regulators and things. You've organised things with the National Centre for Immunisation Research and Surveillance, supporting, you know, regional NITAGs, the National Immunisation Technical Advisory Groups. But then, you know, at my level, at the clinician level, there's so many other you know, you know, I don't want to say low level, but sort of, you know, clinician to clinician sort of interactions. I know that, you know, Fiona Russell at MCRI (Murdoch Children's Research Institute) has worked a long time in Fiji and still has a lot of discussions with them, Josh Francis in the Northern Territory, and has a long history with Timor Leste and has been working there as well.  And I think, Meru Sheel and Chris Hair, you know, they have just informal discussion groups with many Pacific Island clinicians just to say, well, what are the problems you're dealing with, you know, how would we approach this and how can we help you in the Pacific. So there's lots of different, you know, levels at which people can help.  And, obviously, you know, Australia has a lot of links to particularly the Pacific and but also Southeast Asia. And it goes both ways, as well. So you may know that we're dealing with Japanese encephalitis for the first time on Australian mainland. And so I've reached out to my colleagues in Thailand to say, you know, how, how does your Japanese encephalitis programme work and what have you found to be effective, and that's been helpful, having help from people that have experienced with other things. So sharing that expertise around in the region is, is really good.

Dr Stephanie Williams  25:14

You know, I've never had an Australian public health person, clinician person expert, saying no to an opportunity to engage with counterparts in the region and it's just such, I mean, you've given great examples there, but it's such an important part of how we work in health and health security and partnerships, but it does rely on the willingness of Australians to engage and that I think, is a huge asset. Allen, I always learn more than one thing when I talk to you, thank you so much for making the time to join us on the Contain This podcast. I'm sure we'll come back that really thank you for talking with me today.

Prof Allen Cheng  25:57

Thank you so much Steph.

Dr Stephanie Williams  26:01

You've been listening to Professor Allen Cheng, Director of Infection Prevention and Healthcare Epidemiology Unit at Alfred Health and Professor of Infectious Diseases Epidemiology at Monash University. I'm Stephanie Williams, Australia's Ambassador for Regional Health Security, and I spoke to Allen earlier this year for this contain this episode. 

Since we spoke, Australia has moved past the first Omicron variant to what we are now calling the BA2 Omicron variant of COVID-19. As Professor Ching predicted, so far, this variant appears to be more infectious but less severe than the first Omicron variant prompting ATAGI to recommend that a fourth booster shot only be given to Australians aged 65 and over and other vulnerable individuals. 

We hope you join the conversation on our social media pages and in two weeks tune in again for the next episode of Contain This.