What's HIV got to do with a coronavirus vaccine?



And norman. We had on friday that the vaccine which we talked a couple of times about on this podcast saying that it was a really promising candidate has been canned over the fact that people who received it could have a false positive to an hiv test or particular antibody associated with hiv. And we've had a lot of questions from the audience about this. So let's see if we can demystify. These are really felt like a bolt from the blue. We got kenton asking. Can you please explain how a why false positive hiv tests stopped. The queensland trial doesn't this reflect poorly on the hiv test rather than the vaccination. So that's a great question. Canton anita back up and just do a bit of an explanation. Here you listened to colonel cast regular you know that the vaccines and some of the treatments but the vaccines are targeted against the spike. On the surface of crohn's now the problem with the spike is that it changes shape. And you want it to be exactly the right shape for the lock and key mechanism and therefore it's going to be fixed. It changes shape of. It's not attached to the virus itself. Is that what you meant. That's right kind of swings in the breeze a bit now. How the are ours is the no one in the pfizer vaccines novartis's but vaccines do. This is that they've got a genetic variant of which programs a fixed version of the spike protein. So that's how they do it. How the university of queensland vaccine does it is that they've got something called a molecular clamp. So they kind of clamp into position so that it stays in the right shape for the immune system to recognize as a bona feed your at accurate version of the spike protein. So the immune response that you generate is exactly the immune response you want to be able to control the corona virus. Now you gotta be a clamp clampett. So what is what. What's the clamp. You can't do it for the client in the shade. You go to find some way of doing it. And the way the clamp they use in part is the is part of the human immunodeficiency virus. So it's an envelope protein. I think quite crudely although it's called nimble protein that's how they use it in his co. gp forty one and it clamps down the spike and holds in place so that you've got a stable spike for the immune system to respond to. So that's what they use. Hiv's being studied endlessly and they know exactly how these things work. It wasn't as if they didn't expect some antibodies to this part of the human immunodeficiency virus. I'm told that as part of the informed consent people told they might get a transient rise to to hiv antibodies. So that's what's happened here. Is that more people. Got an antibody response an immune response to this part of the human immunodeficiency virus. And that's what killed the vaccine. Not your had issues but we had the antibody response. Here's the problem when you actually do an hiv test you test. A couple of different parts of the virus that the check for the body response to hiv in different parts of different parts of the virus gp forty one is one of the parts. And there's a couple of others now you've got to get more than one of those to have an absolutely definite positive hiv test if all you come up with is gp forty-one then that's you know that's an equivocal test and they've got a taste you further so the problem is that the communist hiv tests include gp forty one in the suite of antibodies. They pick up when the testing for hiv. So the problem is donate blocks you come kneecap positive and they reject your sample or go to do other other ids tests to nil it. It's not as if it's impossible to get over. But it creates a lot of confusion and difficulty out there and and i suppose they just took a risk benefit equation. There was no harm to individuals. And i think you listen to the press conference. Teagan and some of these antibody rises. Were actually tempering. That that's right. So they said that. All of the vaccine as the older people that receive them. Had some level of positivity to hiv even though before the trials they really thought that it was theoretical risk in quite a lawyer one but they did say that even now at least one of the paypal has gone back to zero and the other seem to be declining so it could be a transient thing and they said that they did actually talk. They've had conversations with the government with health bodies about maybe whether the hiv tests should be changed to give people access to the coronavirus vaccine but they decided that i that would be really hard and be in addition to a public health issue around hiv. There's also a really important public perception issue around the vaccines and they wouldn't want people to be put off using the vaccine because of these perceived link with hiv even though there's absolutely no health risk associated with it at all because it's just a tiny little part of the virus that can't suddenly become the virus it's just literally apar- you're molecular part of the virus which is entirely independent says a huge shame and pamela asks. Why did they try using hiv. In the first place. I think the they at the press conference. That's right and one of the big reason is because hiv is just so well studied. And so this this clamp that was talking about before it was crystallized in hiv. I and so because even though. Hiv's are really scary bars or perhaps because it seems like scary virus. We know a lot about it. We started in a lot of detail and so with something. That's a really nine quantity being able to clip these thing out and put it into the vaccine. Seemed like a really sensible choice and because this was the first human trials of this vaccine. They didn't have an opportunity before now to know that this was going to be a risk the issue that we have only working human so they couldn't use them in the animal bottles and it wasn't really a high priority when the outcome that they're looking for is covid not really itchy. Europe was the last question from lou. Lou is asking the the stories seem to suggest that it was abandoned due to a concern about possible public perceptions rather than any real problem with the vaccine is this right is partly right of. Csl was party to that. They're the commercial partner and they've got a marketing issue to explain why this has the while you get a positive. Hiv test. even though it's false positive is enough of an issue reducing vaccine hesitancy. When you've rush through some of these vaccines and then you add hiv on top of it but there are practical issues. Liu and the pro the probably mostly relate to the blood supply you go into give a blood donation they will do a routine. Hiv test on it. And if it comes up positive and you either rejects the blood donation if let's say for example that fifty percent of the australian population got immunized against the with the vaccine and some of them didn't disappear quickly then. They've got to do further testing on the on the blood supply to make sure that it's just. It is truly a false positives. It creates a practical problem. They it also creates a problem for perhaps life insurance. So these things are solvable. I mean if this was the only vaccine available in the world they probably would continue with it but because it's not they've gone for just saying we're just gonna use the overseas vaccines which kind of brings us to some other news. That came out over the weekend so we heard that the yuki vaccine has been canceled. Which is a real blardone scientists but in addition to that glasgow smithkline vaccine has also been paused or cancelled canceled as been paused. So what they had was. They had a problem measuring the virus or the virus particles you know. Basically the corona vars to the vaccine in the in in their samples and they got that wrong and therefore the shoe or the wrong does in the in the samples and they had to had to go back to the drawing board workout test for the the elements of the corona virus in their vaccine and then reinstitute trials in a few months time. So they haven't candid is just the technical problem early on and often dosage does become a problem in vaccine trials. It's not unknown for vaccines to fall over at the dosage stage. And it's worth remembering here. The in the rush to get these vaccines the bit. That's been compressed. Is what's called the phase two trial. So what's happened here with the q. Vaccine it was the phase one trial which is a safety trial which find out this problem with hiv that it was more common than they thought. Normally then you would go to if it was okay in the phase one to phase two trial which is often largely about finding the right does the best fate whether it's a drug over vaccine and that's what's been compressed and they've tried to do phase one phase two trials together or face to face three trials together and the dosage that s- being not very well sorted i in some of the trials so for example. That's one of the problems with the astros trial in a small subs- subset of the trial. They gave half a does again partly because they weren't they weren't formulating in the way that we thought they wear and also a group that was largely under fifty five and they just didn't have time to sort of that element before they got to phase three and then they're probably going to have to double back and recheck all that well.

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