Why stage 3 lockdowns were successful, but not quite enough

Tegan Taylor: Hello, this is Coronacast, a podcast all about the coronavirus. I'm health reporter Tegan Taylor.
Norman Swan: And I'm physician and journalist Dr Norman Swan. It's Tuesday, 4 August.
Tegan Taylor: So, Norman, we are seeing even more shutdowns happening in Victoria, lots of industries are being closed down or restricted in a really dramatic way. What's the purpose of these additional restrictions?
Norman Swan: Well, what you've got in Victoria is a large number of people where you don't know where they caught the infection from. The figures are reasonably stable but they are growing a bit, so the R value is above 1, so you've just got…it's bouncing around, it's probably just growing, but you're getting these cases accumulating and there is no sign of it being turned around, and that means it will just keep on going like this forever if you don't do something about it.
And essentially what you've got to do is stop the transmission of virus where you don't know who's got it, you don't know who are asymptomatic and spreading it, you don't know where these sources are. And rather than going out and hunting them down, which is impossible to do, you just keep people in their homes, don't allow them to circulate, and those viruses will disappear from their bodies over the next two weeks and hopefully they won't be exposed to new virus, so that you can get quite a dramatic reduction over a two- to three-week period, even with quite large numbers as this.
Tegan Taylor: Victorians have been doing it tough for a while now, like the stage 3 restrictions were already pretty tough for a lot of people. Did the stage 3 fail or was it just not working fast enough?
Norman Swan: Well, last night on 7.30 I covered a study from the Burnet Institute, and what they've shown, looking from 1 July on, is that at the beginning of July the R0, the effective reproduction number, in other words the number of people that you spread it to, for every ten people they were spreading it to just over 17 people, 17.5 people. That's a significant growth. Prior to that in some of the hotspots in Melbourne it was 2, so every ten people were spreading it to 20 people.
So what's happened with the stage 3 restrictions, and masks are on top, they don't actually know the effect of masks yet, is that at the end of July ten people were passing it to over 11 people, so that's quite a dramatic reduction. That equates to 20,000 infections in the state of Victoria avoided in July, and perhaps three or four times as many deaths and people in hospital. So it's an extraordinary number and it just shows you what happens when you divert from exponential growth. When you've got exponential growth, you go from very small numbers to very large numbers very quickly, because that was almost a doubling, and now you've got a steady state or a slight growth there, but you are static at that. It may go down a little bit more with masks but it's too early to see the effect of them.
Tegan Taylor: Doesn't that just paint a picture of how contagious this virus is and just…that's a real win for the people of Victoria, that's got to be heartening to go; this is what we avoided, and so we haven't been able to eliminate the spread with what we've done so we need to go further, but surely we can count that as a partial win.
Norman Swan: It is a partial win, it's a huge when, 20,000 people who don't have the infection, and then that 20,000 would have just kept on growing to very large numbers. The fact that it's a small population compared to, say, the United States, doesn't matter, you can still go to very large numbers in a small population very quickly and that is what has been averted by the stage 3. But now going to these new levels of restrictions…so if you are able to bend the curve to that extent in a month, you should be able to really dramatically bend downwards to below 1, in other words for every ten people who are infected, maybe seven or eight get infected.
Tegan Taylor: So comparing the numbers that we've been seeing each day in the hundreds, what would we have been seeing if we hadn't had these restrictions?
Norman Swan: Well, from memory, the Burnet paper showed that on the day when there were over 700 infections in Victoria, if there hadn't been stage 3 lockdown there would have been 3,000 or 4,000 cases on that day, so it's remarkable.
Tegan Taylor: So the other thing that we've seen in the past few days is that other states and territories where the virus is not spreading as widely are bringing back restrictions. So is Victoria spooking everyone or is it just a cautionary tale that we need to be acting before we see the cases going back up?
Norman Swan: No, South Australia is to be commended. They've got two cases in South Australia over the last 24 hours, and they are moving back into restricting how many people can gather in public places, including bars, you've got to be sitting down and so on, the sort of restrictions with social distancing that are very familiar, and they are moving back towards that because whilst they didn't have any virus in the state, that's fine, but now that they do, they've got to remind people about social distancing and trying get it back under control, so they have acted very promptly there and that's great.
Queensland seems to be controlling the outbreak from those two young women who were spreading it around, and I think there was a third young woman, and it got into an aged care centre. Luckily the residential facility that it got into is one where they had good practices in place, and they are a model residential aged care centre. But I think that repeat testing is occurring at that centre, so it's maybe just a bit too early to say that there has been absolutely no transfer, but Queensland seems to have got things under control.
And New South Wales is seeming to bounce along in the mid to high teens each day. It seems so far to have it under control, although there does seem to be new places opening up with outbreaks, and so New South Wales is a work in progress.
Tegan Taylor: There do seem to be cases in New South Wales that aren't attached to known clusters. Is New South Wales where Victoria was a few weeks ago or a month or two ago?
Norman Swan: Well, you're not seeing the growth in numbers in New South Wales, it's all happening at a much lower level. So the accumulation of cases is not as fast, you haven't got those big outbreaks in aged care, meatworks and schools and colleges. You know, there is a college in north-west Melbourne, Al-Taqwa College, which had a big outbreak, you haven't seen those big outbreaks apart from the initial outbreak which was around that hotel in south-west Sydney. It's all been small outbreaks after that fortunately and they seem to be getting on top of it. But like Victoria, there could be subterranean infection happening which you don't know until it breaks out.
Tegan Taylor: Well, let's take some questions from the audience, and one of the questions we get a lot is about the role of kids in the spread of coronavirus, and there is some research out that is shedding a bit more light on this.
Norman Swan: Speaking of shedding, yes, this is about children and their viral load. And what this paper argues is that while people have said with great confidence that children don't spread this virus, they argue in this that schools were shut down so quickly in places like Wuhan and elsewhere that you really aren't too sure of how much children spread this virus. There are quite a few studies that say they don't spread it that much. But this study is quite salutary. So they took children who tested positive, so they had mild-to-moderate symptoms of COVID-19, tested positive, and they measured how much virus they had. And, long story short, they had quite a lot of virus, in fact a lot, which suggested that they could be infectious.
What they didn't do in this was assess how infectious that viral load actually was in those children. So it's still possible that they can carry a lot of virus, but for some reason they are not shedding it. But it is a troubling finding that children are potential sources of infection.
Tegan Taylor: What about rapid testing? We've got Clare and Jackie both asking about whether an easy access rapid test would be a real game-changer for us.
Norman Swan: Well, it would be a game-changer. Just to explain the technology here, so the testing that is done in Australia, the vast majority of it is a swab through the nose into the throat, a nasopharyngeal swab. It then gets taken to the lab and the lab looks for the genetic material of the virus, the RNA of the virus and amplifies the genetic material and that's how they make the test. And it is the most accurate test that we've got at the moment of active infection.
There is another test called an antigen test where they actually look for a chunk of the virus. It sounds confusing, the other one sounds as if it's a chunk of the virus but it's actually a tiny part of the genetic material of the virus rather than a bit of the virus itself. And so this other antigen test looks for a bit of the virus, a chunk of the virus. It's the basis of the rapid test which in a relatively few minutes can give you a result.
So you find out you've got it…it's potentially great because you find out you've got it very quickly, and if you're positive then they can start contact tracing rather than waiting three days. And in some cases in Victoria they are waiting five days for results. 85% of the tests have been done in the private sector, and it's been relatively slow. So if you can find out the same day, isn't that fantastic.
However, the problem with these rapid tests is they are not as accurate as the nasopharyngeal swab, so you can be falsely reassured. We've spoken many times on Coronacast about how potentially inaccurate at times even the most accurate test is, the rapid test is even less accurate than that. So it's hard to actually hang your hat on the results of that test in terms of controlling this virus in a public health sense. But hopefully they will move towards a much more accurate test that you could rely upon, and that would be a fantastic result.
Tegan Taylor: It's a real trade-off, isn't it, with testing, because on one hand you had a rapid test and you had a large amount of it, you could get people through really quickly and get a higher volume of people and maybe capture more virus overall, but at an individual level you may be having a few more people slip through the cracks than you would otherwise.
Norman Swan: Yes, and that's true also of the sputum test that the Doherty Institute instituted. It's a bit less accurate. It still looks for the genetic material but it's taking sputum and it's less accurate than the nose and throat swab, but it's better than not doing any test at all, and the rapid test is better than doing no test at all. But people will slip through the cracks.
Tegan Taylor: Well Coronacasters, if you want to ask us even more questions and see us answer them in real life or at least in real-time, we are having an Instagram live chat tonight, so that's Tuesday, 4 August at 7pm eastern time, all you have to do is make sure you're following ABC Health on Instagram, ask us your questions there, make Norman squirm with your toughest, toughest questions, I can't wait to chuck them all at him in rapid fire.
Norman Swan: I shall have my belt and braces on ready for the questions. And just a little shout-out for our Together in Art Kids exhibition, the latest exhibition is up on the Art Gallery of New South Wales' site. We've got the URL on the Coronacast website, it's togetherinart.org/kids/jumaadi, some fantastic pieces of work, go have a look at them and tell us when you make a comment, which is at abc.net.au/coronavirus, tell us which one is your favourite.
Tegan Taylor: They are so beautiful and so poignant.
Norman Swan: They are, they're fantastic. I like the dog with the back to the child, that's a good one. And we'll see you tomorrow.
Tegan Taylor: See you then.