Tegan Taylor: So Norman, last week you pitched a podcast idea to us, knee cast, based on your own experience with a dodgy knee, and we got such a big response on it, getting all sorts of…’use a walking stick, don’t limp, do this, do that, do your exercises’. Are you doing your exercises?
Norman Swan: I am, it’s agony. I tell you, the hardest one is your buttocks, to strengthen your buttocks is very hard.
Tegan Taylor: I’ll have to take your word for it.
Norman Swan: I’ve never really thought about my buttocks before and trying to strengthen them, it’s tough.
Tegan Taylor: Are you doing squats and deadlifts in the gym?
Norman Swan: I’m doing…what do they call it?…the Romanian dead lift.
Tegan Taylor: Oh yeah, I do some of those sometimes too.
Norman Swan: That’s good for your buttocks, I’m told. Next week I’ll give you an update on my hammies.
Tegan Taylor: We should be buttockscast. No, no, let’s keep on going with corona cast, to show all about the coronavirus. I’m health reporter Tegan Taylor.
Norman Swan: And I’m physician and journalist Dr Norman Swan, and it’s Wednesday, 10 August, 2022.
Tegan Taylor: And we’ve been hearing so much about Omicron variant B5, the biggest BI suppose that we’ve been dealing with recently, and we saw a big peak to this wave through the middle of winter here in Australia. It’s peaking in other places in the world as well though, it’s not just seasonal. But we are starting to see that tail off a bit. It’s still only August though, so is this a little lull or we are maybe on the downward curve of the B5 wave?
Norman Swan: Well, we probably are on the downward curve. It’s always hard to pick the peak, but the peak was probably just before our last corona cast…
Tegan Taylor: We time it well.
Norman Swan: We do time it well. And it seems fairly convincing. New South Wales, just by the time you listen to this Coronacast it may have turned the corner, but New South Wales interestingly on a daily case rate, at least up until the weekend, was 50% higher as a percentage of population, in terms of the daily cases, than the rest of Australia.
Tegan Taylor: So what could be behind that?
Norman Swan: It could be that New South Wales people are better at getting tested. Unlikely, but it’s possible. Remember, we’re not testing systematically the way we did at the height of the pandemic in 2020, 2021 and we are not doing it with PCR, so it’s hard to know, but there may be more testing going on. There may be behaviour, there are fewer people wearing masks indoors than other states, or it may be just the way the virus is circulating. It’s almost impossible to tell, there could be a variety of reasons for it.
Tegan Taylor: I mean, we know that these waves do tail off after a while, they’re called ‘waves’ for a reason, it doesn’t mean that the virus has gone away completely, it’s not unexpected that it would tail off at some stage, but we are thinking that now is the time.
Norman Swan: I think so. I mean, when you look at the aggregate seven-day average for Australia, it really is quite impressive, the way it is going down.
Tegan Taylor: What about deaths?
Norman Swan: Well, deaths have been running quite high, and the running average, at least when we are recording this, is around about 60 to 70 deaths per day. It does look as if there’s a turnaround in deaths, and you’d expect that with a delay in the peak. So the peak was about eight or nine days ago, you would expect the turnaround in deaths probably to be two or three weeks after that. But there is a bit of a turnaround at the moment, so hopefully they are going to continue going down.
Tegan Taylor: Okay, so if we are waving bye-bye to the B5 wave, what’s next? Is this the calm before BA6 or Centurion or some other terrifyingly new variant we haven’t even considered yet?
Norman Swan: Well, as we’ve seen, but it could change, there’s nothing terribly biological about it, is that we have seen a new variant every six months, and as we predicted on corona cast, B4, 5, it’s now really B5 is acting as if it’s a new variant, even though it’s a subvariant of Omicron. Well, 2.75 is the one they are talking about, which is still a subvariant of Omicron, and it’s a bit more infectious, it’s a bit more immune evasive, maybe more contagious in its own right, probably not more virulent. Interestingly the mutations are very complicated, it looks as though 2.75 is more susceptible than other Omicrons to the monoclonal Sotrovimab, which is used therapeutically.
Tegan Taylor: In terms of helping people get better more quickly?
Norman Swan: It’s particularly helping in hospital, that’s right, so it’s not one of the antivirals, it’s a monoclonal. It seems to be tailing off in India, mostly noticed in India but around the world, so it is unclear whether 2.75 will take over. I don’t think it’s one that one would lose sleep over. So the next one could be another variant of Omicron, it seems to be producing a lot of mutations, this family of subvariants, or it could be a new one entirely, or maybe there won’t be any at all, let’s hope.
Tegan Taylor: Wouldn’t that be nice! So how are we faring in terms of vaccination rates? We had very high levels of first and second doses, what about third and fourth doses?
Norman Swan: Well, if you go to the Commonwealth data on this, 96% of people eligible over the age of 16 have had two doses, but only 71% have had three doses who are eligible, and that means 5 million Australians who are eligible for a third dose haven’t had it, which means they are under-immunised, probably seriously under-immunised. And with fourth doses it ranges between 30% and 40%, but of course you can’t have your fourth dose until you’ve had your third dose, it’s kind of a catch.
Tegan Taylor: Indeed.
Norman Swan: So, it’s serious, people need to get their third doses and, if they are eligible, get their fourth.
Tegan Taylor: So can we talk about how severe the disease is that BA5 causes? I mean, I know we just said that we are basically bidding it farewell. Some of the way the severe disease manifests is whether or not you are fully vaccinated, and you just said that a lot of us aren’t. But inherently, how does it compare to other variants?
Norman Swan: Well, the epidemiological data are not entirely clear. There has been a lab study which has not been peer-reviewed, which has come out of Japan, where they’ve got lab models in both hamsters and in the test tube to look at how likely it is that these subvariants disrupt the surface of the lung and blood vessels, and their conclusion from that is that BA5…and this contradicts something we’ve been saying a bit on corona cast, so we have to actually correct that, is they think that BA5 has lower ability to cause disease than the ancestral variant. We’ve been saying, based on early data, that the ability to cause disease is the same as the ancestral strain, the Wuhan strain, but in fact they are saying here, based on this laboratory data, that it has lower pathology potential, but it does have more ability to cause damage than BA1 and BA2.
Tegan Taylor: Okay, so it’s sort of in the middle there.
Norman Swan: It’s worse in terms of inflammation and disruption to the lung tissue in the lab than BA1 and BA2, but still low when you compare it historically to Wuhan, and presumably by inference Delta, although they didn’t look at Delta in this study.
Tegan Taylor: Well, Norman, people continue to send in questions and comments to us via abc.net.au/coronacast, and I thought it would be good to get to a couple of them today. One of them is from Darren who is asking about how best to use a rapid antigen test. He’s saying; ‘RATs swab the nose, I assume that’s because it’s too hard to swab the lungs. Where does the virus actually replicate? Only in the lungs or in the nose too? And what’s the implication on RAT accuracy for someone who is a mouth breather?’ I think he’s saying if it’s only coming from your lungs and you’re not breathing through your nose, are you going to find it there?
Norman Swan: Well, it comes in through the nose, goes into the lungs and replicates there. And there is some evidence that the RAT test is more accurate when you swab the back of the throat, but it’s hard for people often to really effectively swab the back of the throat, but we’ve talked about this on corona cast before, there is a bit of evidence that it’s more accurate if you swab the back of the throat, and that’s presumably because of exactly what Darren is talking about, is that the virus does tend to replicate below the vocal chords, in the lungs and the bronchial tree, and therefore more likely to be up there in the throat than in the nose. I’m a natural mouth breather because I’ve got a septum problem in my nose and I’ve tested positive on two occasions.
Tegan Taylor: Well, there you go. Another question about where the virus goes in your body is from Finton who is saying; is the coronavirus caught by swallowing air into our stomach and then breathing air into our lungs when air passes through our nose? And he is wondering whether breathing through our mouth only, behind a mask, would provide better protection. Can you bypass coronavirus by only breathing through your mouth?
Norman Swan: I think we’re going to have to ask a didgeridoo player to answer this question. But seriously, you don’t need to overcomplicate this, you catch it by it coming in through your nose and mouth, depending where you breathe it in, it goes into your lungs, it replicates and that’s how you catch it. There is some evidence that you can catch it via your gastrointestinal tract, which we talked about early on, and we did talk about whether farting spreads the virus but luckily you’ve usually got a mask on your bum, and the percentage caught through an infected surface, my understanding is that it’s 1% or 2%, it’s actually quite rare.
Tegan Taylor: So, in terms of getting it through a surface.
And that a question from Annabel, saying; of the people who catch coronavirus, how many are asymptomatic? Because someone told her recently they had been really sick with it and they said you’ll know if you’ve had Covid. But she is going, but will I? How will I know? What symptoms will help me to know that I’ve definitely had Covid and not a different respiratory virus?
Norman Swan: Well, by definition if it’s asymptomatic you won’t know. And it’s a really good question, and again as testing has become less systematic, it’s really hard to know. An early study into Omicron at the beginning of the year suggested that it could be 16% or 17% are asymptomatic.
Tegan Taylor: I can only speak from my own experience, I wouldn’t have known it was Covid if I hadn’t tested, I just had a rubbish head cold and felt tired. I’ve felt like that a million times before.
Norman Swan: Yes, but that’s not asymptomatic, that’s symptomatic. What if you’ve just been bouncing around feeling great, no problems at all?
Tegan Taylor: That’s true. Well, if you’ve got any questions or comments, you can let us know by going to abc.net.au/coronacast.
Norman Swan: Or send it in to knee cast and we’ll answer those too.
Tegan Taylor: We’ll see you next time.
Norman Swan: See you then.
