The ambition to eliminate HIV transmission by 2030

Introduction

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5 Live Science

0:58Hello. Welcome to this week's 5 Live Science. I'm Chris Smith from the Naked Scientists. And coming up, the first new treatment for asthma attacks in over half a century. The doctors behind it say it's potentially game-changing. Plus, the International Space Station has sprung a leak and sparked a diplomatic spat. We'll hear where and why. Antarctica's first amber specimen confirms theories that the frozen south was once a tropical rainforest. And a bit later on... It's very scary back in Africa to be diagnosed with HIV.

1:34You most times are scared to tell anybody. You're scared of dying. You're scared of everything. It is World AIDS Day today. And within five years, doctors want to see transmission of the infection eliminated from many countries, including the UK. How are they planning to do it? The Naked Scientists on 5 Live.

Asthma Treatment

1:55First this week, a new study has found that an injection given to people who suffer from asthma or COPD, that's chronic obstructive pulmonary disease, attacks, is much more effective than current treatment with steroid tablets, which alarmingly fail three quarters of the time. The new therapy, which is an antibody that targets a population of white blood cells called eosinophils, which drive the inflammatory response which causes asthma attacks and COPD exacerbations, is called Benrelizumab. And the authors say it's going to be game-changing for millions of people.

2:28Here's Richard Russell at King's College London. We know people have these attacks. So these attacks occur and they affect individuals. They cause loss of lung function. They make them feel really sick. They lead to hospitalisation and indeed, in some cases, lead to death. And the treatments we've had have not changed over 50 years. We give these people with attacks oral corticosteroid treatments, anti-inflammatory therapies. We were then aware that these treatments themselves, one, are not very effective, and two, have got side effects, osteoporosis, diabetes, obesity, skin thinning, bruising, cataracts.

3:03And so we needed to think, you know, can we find a better treatment?

Eosinophilic Inflammation

3:07We identified over 15 years ago now that there are groups of patients who have attacks of a particular pattern of inflammation. We'll call it eosinophilic inflammation. Now, what was really exciting was that in the last few years, we've now got new treatments which are specific to reduce this pattern of inflammation. But what are eosinophils and why are they uniquely bound up with these particular patterns of attacks? Well, that's a really great point.

3:37Eosinophils are part of the immune system. They're white blood cells. They are relatively uncommon in our blood in comparison with other blood cells. And historically, we believe they've been associated with particular things like allergy and indeed asthma, but also worm infection. And we've now recognised that these eosinophils are really important in our guts and in our lungs, particularly at monitoring what is going on in the immune environment. So we recognise these cells are actually really important.

4:09And what happens is when you have an eosinophilic attack, you have an increase in breathlessness, increase in cough and sputum. And in your blood, we can measure an increased level of these eosinophils. And that's what we're targeting with this new treatment. The rationale being then that if there's a lot of these cells and they're linked to attacks, if you reduce the number of them, you should have fewer attacks. Absolutely correct. And that's exactly what we did. And so what we did was design a study using a treatment called benrolizumab. Benrolizumab is an antibody therapy given by injection, which specifically targets eosinophil production and migration into the lungs.

4:45We compared this with standard therapy, oral corticosteroids.

New Therapy

4:50And indeed, we had a third arm, which was a combination of the two treatments together. And how many people did you look at and who? Who were the patients? We looked at 160 patients, 158 to be precise. And these patients were all comers, whether they had asthma or COPD that had an attack. So if you were a patient out there on the street and you had a worsening of your condition, you would come along to us. We would do a blood test at that moment. If your eosinophils were raised, we would then randomize you into the study. So it was everyone with asthma and COPD who had this raised level of eosinophils.

5:24And we followed them for three months, 90 days. Our primary outcome was what we call treatment failure, meaning did your treatment work or not? If your treatment failed, defined by needing more treatment or having to go to hospital or even dying. So we were comparing the failure rates of standard treatment with the failure rates of this new therapy. And how did they compare? What we demonstrated was a couple of things. One, if you have eosinophilic exacerbation and attack of asthma or COPD, you have got, with standard therapy, around a 74% chance of your treatment not working.

6:04Now, that should shock the audience today because I think that's where we are right now. That is standard therapy. Is that good enough? Absolutely not. But what we demonstrated that with the new therapy, we were able to reduce that rate to around 44%, which is a 74% reduction in treatment failure. Is it practical and is it cost effective? Because that's the thing that NICE are very, very keen on making sure that we have drugs that might work. But if they don't work well enough to return a good bang for their buck, they won't say we can use them.

6:35So where do we sit on that line? That's really great. There's two points there. Let me put the first one to bed first. Is it practical? Yes, absolutely is. We have technology which can allow for point-of-care testing of your blood with an answer within seconds, if not a couple of minutes. And that is available right now. And indeed, our standard therapies in hospital can give you a blood result within a few minutes. So it is absolutely practical. The injections can even be given by the patients themselves, but certainly are very, very easy to administer.

7:06And the side effect profile is extremely good. So, you know, we've got experience with these over time. So the practicality, I think, gets a big tick, absolutely.

Practicality

7:14Cost-effectiveness is much more difficult. Steroids are very cheap. But hold on. Steroids fail 75% of the time. So what the heck are we doing with this? And we're exposing people to side effects and risk. So we need to do a bigger study, a phase three, larger scale, multinational study. And then we can then do some cost-effective analysis, which will make the argument, I would hope, to use these treatments. This is a one-off treatment, not recurrent treatment.

7:45And if you end up being admitted to hospital, or even worse, you end up being admitted to intensive care, you're looking at a cost of two, three, four, £5,000 a day. This treatment costs around £1,000. So although it is expensive, if it saves intensive care and even death, that will end up being cost-effective. Exciting stuff. Richard Russell there. And that study he was talking about has just been published in The Lancet Respiratory Medicine.

Space Station Leak

8:10The International Space Station has been a great source of collaboration between NASA and Roscosmos, the Russian space agency, for decades. But the extent of a five-year-old leak, as it turns out, on board the ISS has put Washington and Moscow at loggerheads up in space, as well as here on Earth. Here's Richard Hollingham from the Space Muffins on what we know about the situation. Chris, it's months or years old, and no one quite knows exactly where it is or what caused it.

8:42It could be around the welds in the structure of this section of the space station. Oh, it could just be in the integrity of the metal, as well. And this section, it connects the Russian spacecraft to the station itself. So they have this little tunnel. You have the Progress freighters, which are like uncrewed spacecraft, dock with the station. They go into this tunnel to get all the stuff out, and they put all the rubbish in, and they send the freighter back to burn up in the Earth's atmosphere.

9:14So it's quite a crucial module, but right now they can close the door. So although it's leaking, it's not affecting the integrity of the rest of the station. What's the scale of the leak? How much are they actually losing in gas terms? It's really not a huge amount. It's not like there's a hiss of air going out. It's just a gentle leak over time, like a slow puncture, I guess, on a car or a bike. But, I mean, this module is really old. This has been in space since the year 2000.

9:47These were actually built before then. So it's really getting on in years. It's got this harsh environment. It's got pretty much constant bombardment by micrometeoroids, little tiny space rocks, the risk of space debris also hitting the station too. It's reaching the end of its life, and it looks like this is the first section to really be showing that. But, I mean, it could have happened to another part of the station as well. And when you look at the actual fabric, so the basic whole structure of the station, I mean, this is not thick metal.

10:26This is really centimetres thick. It's not a massive structure because, you know, you've got to launch it into space, and then it doesn't have to be particularly thick once it's in space. But that does mean any leaks or any welds, anything like that, are going to deteriorate over time. And why are NASA and Roscosmos having argy-bargy about it? Russia never seems to admit a problem with its side of the space station or with any of its space programme.

10:56I mean, we see this on the ground, of course, as well. Very thin-skinned, I would say, would be the senior officials of the Russian space programme. I mean, I do think it's extraordinary that, if you think about it, 400 kilometres above our heads on the International Space Station, the Americans and the Russians are cooperating. Meanwhile, on the ground, there's a proxy war between NATO and Russia in Ukraine. So, I think it's almost extraordinary that they've been cooperating for so long.

11:26But there's just this constant pushback on things. Meanwhile, in space, actually, the crew get on really, really well, because they're in this harsh environment, everything's safety-critical, they have to get on well. They're all astronauts. So, what happens if they just carry on rubbing along as they are, and they don't fix this? It'll probably be fine until it's not. That's the problem with these things, particularly as they haven't actually identified what the specific problem is, where the leak is. So, all the time now, they're closing the door to this section of the space station.

11:59If the leak gets worse, they will have to close that door permanently. And if that happens, that means they will not be able to dock the Progress Cargo spacecraft to the station. They'll be then solely, really, probably relying on the American SpaceX. So, they need to fix it. They need to find the leak and fix it, or decide, well, is it fixable? Is there a pinprick there? Is there a failed weld? Or is this something they're going to have to live with? If it is a faulty weld, and there was some sort of knock to that, or it suddenly gave,

12:33then you are in a potentially very dangerous situation if that hatch is open. I mean, you know, really, they've got to keep the space station alive, working for another six years or so. That's the plan at the moment, until 2030, which means this stuff has got to limp on. It would have been in space, operating with people on board for 30 years. I mean, that is extraordinary. Can you repair stuff in space, in the same way as if that was a blow-up boat on the ocean?

13:03You'd put a patch on it, wouldn't you? So, is that sort of thing feasible in space? Yeah, exactly the same. So, in the past, when there was the Mir space station, you may remember in its sort of dying days, there was a massive collision with a cargo module when it hit the space station. That was a catastrophic loss of air, with the crew having to really, you know, just shut the hatches to stop it. They went outside, they repaired it. I mean, yeah, you can use tape. There's a lot of tape used on the space station to hold stuff to walls and things.

13:38You could just stick some tape over it. It would be absolutely fine. So, it is fixable. The issue seems to be with this particular leak is they don't know exactly where it is or what it is. And no one seems to be investigating to find that. Richard Hollingham from the Space Moffins there. This is 5 Live Science with me, Chris Smith.

Ancient Footprints

13:58And still to come, we'll hear from the team who've discovered fossilised tree resin, otherwise known as amber, down in Antarctica. What are the implications of that? And the global fight against new HIV infections for this, World AIDS Day. But first, researchers say that they've found the 1.5 million year old crisscrossing footprints of two different species of early human ancestors preserved in mud at the same spot in Kenya. Now, nearly half a century ago, in the same geography, roughly, the famous British paleoanthropologist Mary Leakey made a similar discovery of footprints dating back, in that case, over 3.5 million years.

14:37Now, those footprints were some of the strongest evidence at the time that those ancestors that made them walked on two feet. Well, now, the international team who've made the new discovery, which also actually includes one of Mary Leakey's descendants, say that their findings prove that at least two different ancient hominin species were near neighbours and possibly even friends. Who knows? Here's Craig Fibel at Rutgers University. This is a trackway from 1.5 million years ago that represents a beach on an ancient lake.

15:12And on that beach surface, we have the trackways of not only a lot of birds and other animals, but two of our ancient cousins, one walking along the beach and one at some point crossing that trackway. So we can see two different trails on this surface. And are these two different species, effectively? They're two different branches of life's evolutionary past? For the first time, I think we can actually distinguish individual footprints and begin to tell that at least they're different,

15:45that there are two different forms here. And so we can tell them apart. And that's really the novelty of this particular discovery, I think, that we can recognise that they're in the same place, maybe not at exactly the same time, but that they passed across the same beach probably within a few hours or a couple of days of each other. And what were the two, you're calling them cousins, but what were the two groups that you think made these footprints? One of them is the lineage that leads directly to us, so our direct ancestor.

16:16And that would have looked very much, I think, as we do today, a very sort of long-bodied, tall form. But the other cousin was very, very different. It was a shorter, stouter, more robustly built cousin. And perhaps the main distinction between the two is that we think our ancestors were already into scavenging for meat and marrow and having sort of an omnivore's diet, whereas this other stockier cousin was perhaps still more of a vegetarian.

16:50We often think of the timeline of evolution as one thing turns into the next, turns into the next. But what this is saying is actually something quite different, which is something we've suspected that these things were all going on and around in an overlapping way. They were around simultaneously. It's like nature was doing an experiment with lots of different forms alongside each other. In this particular time span, one and a half million years ago, there was quite a bit more diversity than we have in the world today. And so not only were there different kinds of giraffe or different kinds of antelope, even in our own group, we had cousins that were very similar to ourselves, but were different species.

17:31And today we're the only surviving species. But we had a number of these cousins who have all gone extinct over time. How did you find these footprints? Where are they? And how do you know, just on the basis of a footprint, that one is Homo, our lineage, and the other is this other group, which are a bit stockier, a bit shorter, and into eating vegetables and so on? The footprints are found in northern Kenya, up towards the Ethiopian border, on the eastern side of Lake Turkana. They're in deposits that represent an ancient lake where a river was coming in near the shoreline of the lake.

18:08So that would have been the setting for this particular several days of fossil record. A number of different birds and animals were wandering along the beach, and all of their tracks are preserved on this surface. Footprints preserve very nicely in damp sediment, and that's part of the story here. Very, very nicely formed in the soft sediment. And then a nearby river gently washed in sand that buried them and preserved them to the present day.

18:42And that enables you, with the detail you've got there, to say, well, these are definitely the footprints of one group, and these are definitely the footprints of the other. That was the surprise in this discovery. And in part, the technology and our understanding of feet and how feet operate, sort of the locomotion of human ancestors, has advanced a lot. So that looking at the details of these feet, it was very apparent that there were two different ways of walking here, two different kinds of getting across the landscape.

19:13And that made these two sets of footprints quite distinctive. Craig Freibull there. He's at Rutgers University, and those observations have just been published in the journal Science.

Amber Discovery

19:23Now, sticking with ancient fossilised relics of the past, scientists in Germany have said that they've discovered the first documented deposits of amber fossilised tree resin in Antarctica. This means that the resin has now been found on every continent on the planet. And down south, it paints a picture of a formerly heavily forested Antarctic continent millions of years ago. Here's Johan Klagers at the Alfred Wegener Institute. We found for the first time amber in Antarctica, so fossilised resin.

19:57So what trees exude when they try to seal injuries, for example. And that was really the first time in Antarctica. So far on all continents, amber was found and discovered, but not in Antarctica yet. So that was really exciting for us. Where did you find it? We found it in a marine sediment core, which is very unusual because normally you don't find these things in a marine sediment core.

20:27But at the time when the resin deposited, it was a terrestrial ecosystem, so on land. And therefore, it is a direct indication and direct evidence for us that a forest must have existed in the location where we drilled. You don't think the amber could have got there via another route, I don't know, an animal took it or currents took it, something like that? No, because we know exactly what this environment was about because we published another paper in 2020 where we reconstructed a temperate rainforest in the same location.

21:05And sediments were completely undisturbed and pristinely preserved. We have a root system in there. We have pollen and spores from these plants back then. So we know that the sediments were pristinely preserved. And now we looked a little closer in the particular layer of that sediment core. And there we found this amber. So the first direct evidence for the presence of resin producing trees in that particular location. And critically, when does that date from then?

21:37In between, let's say, 93 to 82 million years. And this is the time where the dinosaurs lived. We call that the mid-Cretaceous, which is about 90 million years ago. Why was Antarctica so different then compared to how it is now? Interestingly, the location of Antarctica was not so much different. So the location where we drilled today is on 73 degrees south, which is pretty far south.

22:09But back then it was on 82 degrees south. So only 900 kilometers away from the South Pole. But, and this is a big but, the continent of Antarctica was still connected to the other continents in the Southern Hemisphere. So South America, South Africa, and also Australia and New Zealand. So there were land connections in between those continents. And it was the final breakup of those continents from Antarctica.

22:40So the final days of the supercontinent. And we call that Gondwana. And that was about 90 million years ago. Why, though, is it now so cold? And back then it was much warmer, despite being in the same geographical position, and warm enough to sustain a big rainforest. That is a very good question. And we know exactly why that is. Because the continents were connected back then. And also ocean currents and atmospheric currents, so winds, were able to reach the Antarctic continent and transport warm water and air masses towards the continent much further south than it can be done today.

23:21And if you go back further in time, so to a time window 34 million years before today, then we had a time where those continents, so South America, Africa, and Australia, were already very far away because of continental drift from Antarctica. And therefore, an ocean current could evolve in between Antarctica and the other currents, and we know that today as the circumpolar Antarctic current.

23:56And not only that, also at this time, 34 million years ago, the CO2 content globally in the atmosphere dropped significantly. And those two things together, and they are, of course, also connected, those things, they led to a significant cooling of the entire planet. If Antarctica was connected to these other continents to create not just those climate effects, but also to allow other things to get there, does that mean there were animals down there as well then, in much greater profusion than just the very specialist species that we see today?

24:34Yeah, definitely. So, from the Antarctic Peninsula, for example, we have many evidence for the presence of, for example, dinosaurs. We also have evidence for insects and also frogs, for example, that a little bit later in the Eocene. But still, it must have been a very diverse environment down there. And just imagine, on 82 degrees south, we had a temperate rainforest environment that could survive in those conditions, even though we also back then, of course, had almost four months total darkness because of the polar night.

25:11Absolutely fascinating. Johan Klark is there at the Alfred Wegener Institute, and those findings he was talking about have just been published in the journal Nature. Today, it being Sunday, the 1st of December, and happy Advent, by the way, is World AIDS Day.

World AIDS Day

25:26Where are we in the fight against new global infections with HIV? Welcome back to 5 Live Science, with me, Chris Smith. And today, on World AIDS Day, HIV, and a mission to eliminate its transmission by 2030, is going under our microscope. The Naked Scientists on 5 Live. The AIDS pandemic is, unarguably, the worst health threat to have confronted the population in the modern era. We believe close to 100 million people have died of the disease so far since it first emerged in the early 1900s.

26:01It's proven an incredibly difficult nut to crack. When I first went to medical school in 1993, a patient with advanced AIDS, and just weeks away from dying, came to talk to us. Now, that rarely happens in first world countries these days, thanks to breakthrough scientific discoveries which have created a host of drugs which, when used in combination, can convert the disease into a chronic condition that one just lives with. Regrettably, many countries don't have access to these treatments, and they can't afford them. So the emphasis is instead very much on preventing infection, rather than trying to cure it.

26:36But so far, efforts to develop effective vaccines have failed. This year, in fact, another two vaccine candidates failed to make it through clinical trials. Thankfully, the availability of newer drug regimens, including PrEP, pre-exposure prophylaxis, are helping us to turn the corner. This involves using anti-HIV drugs to protect vulnerable people from picking up the infection in the first place. And new, longer-acting forms are becoming available, and they are forming the backbone of an international strategy

27:08that's aiming to bring an end to new cases of HIV by as soon as 2030. One of the major frustrations holding back progress, though, is stigma, which is deterring people from getting tested and contributing to the persistence of the pandemic. I've been speaking to Hayward Dikibo, who caught HIV in Nigeria. It's very scary, back in Africa, to be diagnosed with HIV. You most times are scared to tell anybody. You're scared of dying. You're scared of everything.

27:39Everything. How did you know you had it? There was a bit of sensitization as to HIV. I had just left high school, and I just took myself out of fear to the hospital to run a test and was asked to come back the next day. I initially was given a result that said I was positive, only to find out that it wasn't my own result. I got kind of relieved until I saw my result and it came out positive as well. So that was how I found out.

28:10And how old would you have been at the time that that diagnosis was made? I would have been just before my 17th birthday. Was there anyone you could confide in? Friends, other people of sort of similar age, similar situation? Because of the peculiarity of Nigeria at that time, where the culture of shame and discrimination was really high, still is. There was no one I could talk to. I couldn't even get like an accountability partner. I had to phone in an activist that was in the United Kingdom to present his number for an accountability partner.

28:47So you couldn't even tell your family, for example? Oh my, that would have meant me, you know, going through another level of trauma. So do you think then that this is seriously hampering people seeking testing? Because you were obviously quite forward thinking and thought, well, I want to know. But there must be people who would think, confronted by those sorts of barriers and risks, they'd rather not know. Oh yes, this is actually, it actually poses a limitation because you even find situations where the healthcare providers that are supposed to protect and respect confidentiality, also play into stereotyping, discriminating and shaming people living with HIV.

29:31Have you confided in your family since? So many years ago, I did try to make it open to them and they made a joke out of it, not believing. But yes, since I moved to the UK, I did, I have communicated because I happen to not, I've only been the only person I've waited in also counselling a couple of family members that, you know, found out that they were positive. I was going to say, did anyone else in your family then come back to you and say, well, actually, I think I might be in the same boat? Oh yes, some people, not coming back to me, they found out and, you know, their stories came out and I had to encourage them and walk them through the walk.

30:12Hayward Dickiebo there, making a strong case for how discrimination and fear drive HIV diagnosis underground, which is inevitably hampering measures to try and control the epidemic, especially in Africa, where the burden of the disease is greatest. In fact, every minute that ticks past on this programme currently marks another two new infections, half of them in Africa. So this really matters, especially since UNAIDS have set that target of halting HIV transmission by 2030. Here in the UK, the Terence Higgins Trust, which supports people living with HIV, has also embraced that target, aiming to end new cases in England by the same date.

30:52So how are they planning to go about it? Here's Richard Angel. He's the chief executive of the Terence Higgins Trust. The UK government agreed to make the UNAIDS goal of ending new cases of HIV by 2030 a government goal. We, as the charity sector, ourselves at Terence Higgins Trust, our friends at National AIDS Trust and the Elton John AIDS Foundation, came together to create a HIV commission to really give them a blueprint on how they turn that aspiration into reality. The government's response to that was to draft a HIV action plan that took us from 2021 to where we are today.

31:30And the newly elected government here in the UK has committed to renewing that action plan to learn the lessons of what's been successful on the reduction of transmissions that's taken place to date and really refocus on the goal of getting to zero and the kind of strategies it will involve to achieve that. What does the HIV landscape in a country like the UK look like at the moment in terms of numbers and also rates of new cases, etc?

32:00In the UK, there's about 106,000 people who are living with HIV. All but 5,000 know about it. So the key task in ending the onward transmission of HIV is to find the 5,150 people across the UK that are living with HIV but don't know about it yet. And the trick is to make sure they're testing for HIV. Now, obviously, to test those 5,000 people, you need to test a much bigger cohort and pool of people to do that. Most of that work is done in sexual health services. We've had some great innovations in recent years that have interrupted people's care pathway and where they're using our health service and inserted a HIV test there.

32:40And we found some people who had no idea they might be living with HIV and made sure they are diagnosed and linked to treatment. What proportion are homegrown and what proportion are coming in? We've had an anomaly in the most recent years because, as the government has changed the visa rules post-Brexit, they have been seeking to attract in workers from countries that have a high prevalence of HIV. So if you're bringing people in from a high prevalence country, it's not surprising if a significant number of them are living with HIV.

33:12But the experience, overwhelmingly, is those people coming to the UK are already on medication and have controlled HIV. So those who are coming into the UK appear in the statistics as people who are kind of new in the UK with HIV, but they're not bringing in their HIV per se. And then, crucially, they're not bringing in transmissible HIV to the UK. But we've got about 2,500, essentially, newly diagnosed people that had a transmission of HIV here in the UK. And that number is broadly down on where we've been in previous years, but starting as a plateau as we get nearer to zero.

33:48And the challenge is you need to do more and more tests to find fewer and fewer people. How are those transmissions that we are home-growing and we can't account for on the basis of people who are coming to the UK with a known diagnosis, as you just outlined? How do those transmissions occur and among which groups? Essentially, now it's likely to be from people who are men who have sex with men or people who are having sex between men and women. The transmissions amongst intrusive drug users is incredibly low and the UK has eliminated vertical transmission,

34:20which is what we call mother-to-child transmission, by doing a form of testing that everybody gets in antenatal services when they're pregnant. Given that you can define and qualify who the risk groups are so well, you must therefore have some pretty clear ideas as to the best strategy to stop this. What is that strategy? The strategies that work are programmes that destigmatise testing for people and encourage people to take up innovative and online, confidential and free forms of testing.

34:55So we run a very successful HIV testing week every year that gets 25,000 first-time testers and diagnoses a significant number of people with HIV each year. The things that are starting to work as we are looking for cohorts in smaller and smaller proportions in bigger and bigger population groups are where we're interrupting people's care pathway. So in now 81 A&E's across the country, there is a form of opt-out testing for everyone who goes to an accident and emergency department.

35:28And that means that if you are turning up in an NHS setting and you're having bloods taken, you will automatically be tested for HIV, Hep C and often Hep B. And that has found about 1,200 people who have been living with HIV but didn't know about it. And we're looking to expand that to multi-year programmes but also to other settings and would like to see anybody who's engaging in a termination of pregnancy or having an abortion automatically be offered a HIV and STI screening test.

35:58Those who are using dermatology services to make sure they're regularly tested for HIV, everyone who goes to the sexual health clinic, make sure they leave without or don't leave without getting a HIV test. Those are excellent but also very much reactive to what's gone on. What about the flip side, the proactivity, doing things to stop people catching it in the first place? What sort of strategies have you got there? Because you've got to do that as well as just pick people up and put them on treatment, haven't you?

36:31Absolutely. So there's key tools to preventing HIV transmission. Firstly, that the person living with HIV knows that they're living with HIV so they can get medication only for their health care. But so they can reduce their viral load and make sure they can't pass on HIV to other people. The second is that those who test negative, they can use condoms to stop HIV transmission if they're having sex. And if they are having sex without a condom, there is a drug called PrEP. PrEP is a drug you might take daily or around a sex-based event that you might be having in your life.

37:05And if you take it correctly, it will stop the onward transmission of HIV. And if it were to enter your system, it wouldn't be able to take hold in your cells in the way it would with somebody who doesn't take that drug. So it's a really important tool for people. And we are doing lots of work to promote that going forward. And we're working with the UK Health Security Agency to make sure that those who, particularly AI in the system, might identify as having a PrEP need and a need to use a HIV prevention tool, that more of those are getting that need.

37:40Richard Angel there, the Chief Executive of the Terence Higgins Trust. Optimistic, but realistic. Now, one continent stands out as bearing the brunt of HIV disease, and that's Africa. It accounts for two-thirds of the world's AIDS burden, with 27 million people living with the virus. And most of them live in the south, with disease prevalence being particularly high in Lesotho, Botswana, Zimbabwe, Eswatini and South Africa. Now, in the latter case, in some locales, as many as one in every two young black women attending antenatal clinics

38:15are testing positive. So why is this so high? And what measures can be brought to bear to stop that level of spread? Slim Abdul-Karim is a world-leading epidemiologist and virologist at the University of KwaZulu-Natal in South Africa.

HIV in Africa

38:29He also chairs the UNAIDS Scientific Expert Panel. Globally, we are seeing a steady trend in HIV of declining incidence rates and prevalence. And that's true as much in Africa as it is in most other parts of the world. However, at a global level, there are three groups where incidence has been somewhat more recalcitrant. One of those is in Southern Africa. Now, Southern Africa comprises about half of the global epidemic.

39:03And within Southern Africa, South Africa accounts for about one-fifth of the global burden of HIV. And within South Africa, the group that's at the highest risk of HIV are young women. Is the reason that South Africa has such high prevalence because it's also slightly unusual amongst African nations in being quite moneyed and therefore one of the few countries that could afford quite aggressive treatment for HIV earlier on in the pandemic.

39:38And so you've kept people alive and well who otherwise might not have been in a less well-developed setting. In most of Southern Africa, the high rates of HIV in young women are being driven by what is referred to as age disparate sex. Put another way, this is about teenage girls who are having sex with men who are about 10 years or so older than they are.

40:11Put another way, we have what we call the cycle of HIV transmission. Men in their late 20s, early 30s are having sex with these teenage girls, these young girls below the age of 25. These young girls then grow up and when they reach their late 20s and 30s, they have a very high prevalence of HIV. In some communities in KwaZulu-Natal, over half of the women in their 30s have HIV.

40:44These women are now having sex with men that they are going to marry as their husbands or their long-term partners. And so these women then infect men in their 30s. These men in their 30s have sex with teenage girls. They infect the teenage girls. Those girls grow up, when they reach 30, they infect the next group of 30-year-old men who infect the next. So this cycle continues. And the problem you have is that when you look at the technologies to prevent HIV,

41:18what you used to euphemistically call the ABCs, abstinence, be faithful, condoms, and circumcised, those technologies essentially are under the control of men. And so we didn't really have technologies that women could use to control their risk until along comes PrEP. PrEP, pre-exposure prophylaxis, is used in over 100 countries throughout the world, and it now gives women the power and the ability to control their risk of HIV.

41:54A challenge, though, is that it's very hard for somebody, especially a young teenage girl, to contemplate that she's going to get HIV, and so she's better going to stand in the queue, you know, take the bus, go to the clinic, get the tablets that she's got to take every day. Now, that could possibly change because we have newer technologies, in particular, an injection that you can take once every six months.

42:27This particular injection, if taken once every six months, it was shown to be 100% effective in young women. And that's a very powerful tool. Is there a risk, though, that if people use things like these pre-exposure prophylaxis approaches, that they are then less careful? And you prevent one disease, and HIV is very important, yes, but are people then placing themselves at risk of others, because they're not using condoms, other barrier methods, for example?

42:59In most of the places where we do reproductive health promotion, it does not lead to, you know, everybody just having sex. But what does happen is that when these educated individuals do have sex, they understand the importance of protection. Now, we have seen with pre-exposure prophylaxis that they are, in certain instances, a situation where we see an increase in the prevalence of gonorrhea.

43:30In other words, we are seeing sexual activity, and we are seeing a risk of other sexually transmitted infections. But overall, the key goal, which is to reduce the prevalence of HIV, which is the disease that can't be cured, the focus is on trying to bring down the number of new infections with HIV. South Africa's Slim Abdul Karim. Now, as Slim was just explaining, the southern region of Africa,

44:01the epicentre of the epidemic, faces unique problems, including a very high caseload among adolescents and young women. So what are the solutions? Well, we put in a call to Bahuma Tatanji,

Fighting HIV

44:11who's a Cameroonian-born doctor and infectious disease specialist at Emory University. She told us what we do and what we don't have in our arsenal when it comes to fighting the spread of HIV. One of the biggest barriers remains the fact that we don't actually have a vaccine that effectively prevents HIV acquisition. So what we really have at our disposal remains getting as many people who are living with HIV on antiretroviral therapy, but also being able to provide pre-exposure prophylactic modalities

44:46to individuals who are at higher risk for acquiring HIV. And we're not hitting the targets where these are concerned. What sort of levels are we getting to? Most countries in Africa are approaching the 80% treatment coverage targets for adults. But it's important to note that when it comes to pediatric HIV, that number and those targets are unfortunately not being met, with only about 50% of children living with HIV in Africa

45:18currently being on antiretroviral therapy. Where pre-exposure prophylaxis is concerned, the numbers there are a little bit more dire in terms of the regions hitting their targets and actually getting pre-exposure prophylaxis readily available to populations that are most likely to benefit. In Eastern and Southern Africa, these targets are on track to meet the goals that were set to be achieved by 2025. But in Western Central Africa,

45:49we still have significantly low levels of PrEP coverage. The target for PrEP coverage set for 2025 was the hope to get 21.5 million people on PrEP, but currently there are only about 3.5 million people who are receiving pre-exposure prophylaxis for HIV. What's the barrier to getting to the number we want? Why are we at the number we currently are? I would think that one of the biggest barriers is really there's still a lot of stigma and discrimination

46:19that is associated with having HIV or being someone who is in a group that may be at higher risk for acquiring HIV. Additionally, there have been issues around funding for pre-exposure prophylaxis, with some countries not necessarily having the requisite resources to actually make these prophylactic treatments available on a broad scale. In terms of meeting the targets for treatment, the biggest barriers remain testing people

46:51and actually having people know their HIV status. What do you think we can do about this? Where do you think the solution lies? Because you've outlined what the frustrations are, but it's not obvious what we do then to solve that. One of the key developments that gives me a lot of hope is the advent of long-acting PrEP modalities, which bring with them a layer of flexibility in terms of options and choice for people who are likely to benefit from pre-exposure prophylaxis.

47:25Now, having this degree of flexibility and choice means that you are removing barriers, either people having to go to a healthcare facility to be able to pick up medication or just being able to use pre-exposure prophylaxis in a manner that is more discreet than having to take a pill a day. Is this a short-term sticking plaster or is this part of a longer-term strategy to try to bear down on transmission and ultimately stop it?

47:55Or is it both? Because one could see that if we could drive the number of people who are actively, acutely infected right down, we actually really do slow down the transmission of the disease because people are most infectious with HIV when they're first infected. That is absolutely correct. I think that it is both. But I would caveat that with the fact that we've now had pre-exposure prophylaxis for 12 years in the form of a once-daily pill. And still we're seeing approximately 120,000 new infections of HIV

48:29in Western and Central Africa per year. Now, although the modalities that I have described hold the potential of reducing transmissions, they would only be able to have maximum impact if we're actually able to get them to the people that need them. Additionally, to your point about people with low viral loads or undetectable viral loads not being able to pass on the virus, that's why it's important that

49:00even if we're focusing on pre-exposure prophylaxis to prevent acquisition of HIV, we must also ensure that we are effectively treating the people who have HIV to make sure that their viral loads are undetectable so that they also cannot transmit. Is there a risk when we give wide-scale use of drugs in the same way that with antibiotics, the more we use antibiotics, the more antibiotic resistance that we're going to see? If we are not careful with how we deploy drugs

49:33at this problem, there is a chance we could accelerate the rate of antiretroviral drug resistance and therefore we could pull the rug from under the use of those agents, not just in the African countries where they're being deployed, but potentially all over the world if those resistant forms spread. That is absolutely correct. And we have already seen reported in the clinical trials for some of the long-acting preventative modalities that exist reports of individuals who have acquired drug resistance

50:03to these medications when they acquired an HIV infection while using them. Reassuringly, the rates of this occurrence have been low. And I think that with having long-acting pre-exposure prophylaxis, the one thing that we get is we know that the individual is taking the drug because unlike the pills where you are really relying on an individual being able to take one pill every day, oftentimes in unsupervised settings,

50:33and you're trusting them to adhere to the therapy to maximise its effectiveness. Infectious diseases specialist Bahuma Titangi there from Emory University. It's now over 40 years since HIV was discovered and confirmed to be the cause of AIDS, the immune deficiency syndrome that characterises the infection. In that time, we've battled very hard and so far failed to develop vaccines to stop the spread of the disease which has so far killed millions of people. But I come away, having listened to the sentiments and the perspectives that we've heard this week,

51:04feeling more positive than I have in a very long time. There's a stronger optimism and sense of purpose and direction and a way to achieve the end goal of stopping HIV spreading worldwide in the next decade. Let's hope we can achieve it. The Naked Scientists on 5 Live. Next time, we are going nuclear. Is this much maligned energy resource actually going to be key to meeting our 21st century energy needs and obligations? We will find out. And if you'd like to join in with that conversation,

51:34do please drop us a line. It's 5livescience at bbc.co.uk. In the meantime, from me, Chris Smith, thank you for listening and from all of us here at the Naked Scientist team, until next time, goodbye. For support on topics covered in this programme, you can get details of organisations within the UK by visiting the BBC Action 9 website, bbc.co.uk slash action 9. I'm Matt Shorley, coming to you live from Westminster, Monday to Friday from 2 o'clock. It's politics, but how it affects you.

52:04It's the funny stories. The people and the personalities that make up the Westminster village. But I want to explain how it works. Order! Order! I've worked there for 20 years now. I really know all the people that require corridors and I know how to find the stories about what's really happening in politics which affect you. As soon as the news breaks, I can bang on the wall and one of the BBC correspondents will come running in and tell us what's going on. Matt Shorley, Monday to Friday from 2 on BBC Radio 5 Live.