HPV vaccine uptake wanes, and boozeless beer health concerns
In this edition of The Naked Scientists: HPV vaccination rates are waning. We examine the importance of the jab. Also ahead: why Africa is key to understanding the evolution of early humans. Plus, the reasons alcohol-free booze might actually not be all that good for us...
In this episode
01:32 - HPV vaccine uptake is falling worldwide
HPV vaccine uptake is falling worldwide
Margaret Stanley, University of Cambridge
Doctors around the world are raising concerns about falling vaccination rates for the Human Papillomavirus, or HPV - the viral infection that causes cervical cancer. The HPV vaccine is typically offered to adolescents in school and has been a massive public health success story, cutting cervical cancer rates by up to 99% in countries with high uptake. But recent data from Scotland, echoed in other countries, shows a worrying decline in vaccination rates, particularly among young people in more deprived communities. Public health officials warn that this could reverse the earlier gains and undermine efforts to eliminate cervical cancer as a global health threat. Margaret Stanley is Emeritus Professor of Epithelial Biology at the University of Cambridge; she’s an internationally recognised expert on HPV and cervical cancer prevention, and helped to develop the cervical cancer vaccine we now use…
Margaret - HPV vaccine was introduced in the UK in 2008. The Scots evaluated its impact over the 10 years of vaccination up to about 2020. What they found was in the 13 year olds who had received the full vaccine dosage, when they arrived for their first smear at the age of 25, there were no invasive cancers. Let me put that in context. The highest number of invasive cervical cancers, the real thing that kills you is in the 25 to 35 age group. And so the fact that this group was showing such a massive reduction, I tell you, this is a real public health triumph. HPV causes 5% of all cancers globally. Now, across the world, where you've had high coverage of this vaccine, 80 to 90% of girls immunised, then you've had reductions in cancer. If the coverage drops, then that possibly will disappear.
Chris - What sorts of rates are we now seeing then? And what sorts of rates of vaccine uptake were we seeing?
Margaret - Scotland before COVID had 90 to 92% coverage of girls. And the boys were coming in and they were getting high coverage too. Since the lockdown and COVID, when the schools closed and therefore the programme was tremendously effected, then it's dropped to about 65%, 70%. In some parts of the country, you're looking at 40%.
Chris - Why in the particular groups that we're seeing this drop though? Because specifically, it's not across the board, is it? It's certain communities where the uptake appears to have really plummeted. So why is that? And is there anything that can be done about that?
Margaret - This is a sexually transmitted infection. And particular religious groups, Islamic, Orthodox Jews, Orthodox Catholics, they are reluctant because they're worried about the sexual transmission and the possibility that this will make the teens more promiscuous. Although I have to say all the evidence says that's rubbish, that it doesn't change their behaviour. And then COVID did all sorts of dreadful damage. And one of the damage was to the trust that people have in medicine and in science. And so they're a significant tranche of the population, which is very uncertain about the benefits of a vaccine you're delivering to a 13-year-old. For a disease, they're not going to get until they're 30, 35.
Chris - Are you expecting then, off the back of this, to see in subsequent years, a resurgence of cervical cancer cases from a near suppression to zero to cases emerging again?
Margaret - I hope not. We've tried to fireproof the programme in the UK as much as possible, because we immunise boys. So the transmission between the two sexes is blocked. So because we've fireproofed it, I'm hoping that we won't see significant failure to fall.
06:16 - Humanity's road to dominance began earlier than expected
Humanity's road to dominance began earlier than expected
Andrea Manica, University of Cambridge
For a long time, the story of human evolution has focused on the moment our human ancestors left Africa, around 50,000 years ago, to spread across the globe. But why only then? Why not before? Well now a new study published in Nature reveals that - from around 70,000 years ago - early humans began to adapt to dramatically different environments across the continent, becoming much better at existing in more extreme conditions. This time period is also reflected in a change in the appearance of these ancestors: they all began to look a lot more alike, evidence, Andrea Manica, professor of evolutionary ecology at the University of Cambridge, argues of the population of Africa interacting a lot more closely, and likely sharing survival tactics in the process…
Andrea - There is a really interesting puzzle in our origins which is we all derive from a group of people that came out of Africa about 50,000 years ago, and yet what we know is that people tried to come out of Africa many times before, and yet they left no trace.
Chris - Well, if they left no trace, how do you know they did that?
Andrea - Well, they left no trace in our genes, in the people that are here contemporarily, but actually there are lots of archaeological evidence, archaeological sites that show us that they were there before.
Chris - In essence then, they tried and failed. Andrea - Yes, they somehow didn't manage it. Chris - The question then becomes, well, when it did happen, why then?
Andrea - Well, that was our big question now, and what we see is that 70,000 years ago, suddenly people changed the way they're using their environment. They really start using the most extreme environments. They somehow learn how to cope with the deepest forests, the driest deserts, and they really manage to do things that they couldn't do before.
Chris - Is that what has emerged from this study? Your argumentation is that something switched and we suddenly unlocked our potential. We became much better at coping with the exigencies of the environment we find ourselves in, and that opened the door to the rest of the world from Africa.
Andrea - Yes, that was the moment when we became, in a way, the ultimate generalist that could really cope with lots of challenges.
Chris - How have you arrived at that conclusion, first and foremost?
Andrea - Well, what we did was actually to really focus on Africa, because what people had done before was more to think about what might have happened after their exit, whereas we really want to look at what people were doing before they came out. And so what we did was actually to work with archaeologists, and we put together information about every single archaeological site in Africa, the dates, and therefore we knew where people were, and then we linked those with reconstructions in climate. That's kind of using the climate models that people used to predict climate change, but used backwards. And so at that point we could actually say where people lived, but also what kind of conditions they lived in. And that's what allows us to see that actually suddenly, 70,000 years ago, they were using the kind of environments that before they couldn't really handle.
Chris - But you've turned one question into another, which is, well why did they suddenly find themselves able to do that?
Andrea - Absolutely. And we can't be completely sure of it, but we do have an idea, which is there is nothing special in the archaeological record at that time that suggests there was a magic invention in that particular instance. In a way that makes sense, because they're suddenly tackling very different environments. They're tackling wet places and dry places all at the same time. But there is one interesting cue that gives us an idea of what might be happening, which is that 70,000 years ago is also when we see the anatomy of humans across the whole continent becoming much more similar. So what we think is the moment when people are interacting much more, moving much more, much more in contact. And that contact, in a way, made everyone a bit more similar. But it also meant that, in a way, they probably exchanged ideas. Ideas were moving, ideas were created, and they were kept and exchanged. And that probably gave them the ability to suddenly deal with very, very different challenges.
Chris - You don't think that that happens to also coincide with the emergence of languages or something like that, do you? Because if you've got that sudden dramatic ability to do what must amount to the exchange of information and knowledge and to pass that on, language would be a really good catalyst for that. Or do we think language evolved many, many years before that?
Andrea - It's very difficult to say because, in a way, there is nothing left about languages. What we know, in terms, obviously, what they were speaking, what we know is that, in a way, symbolic art, so when people start thinking much more in an abstract way, actually happens earlier than that. So we don't think that there is a major, in a way, change in the way the brain was working at that particular point. So we think that probably that was already around, but 70,000 years ago is when people are interacting enough to really take advantage of something like language, that kind of cultural ability to build ideas and, in a way, build ideas upon ideas and therefore come up with something that is better than the sum of the individual parts.
Chris - Now we're talking here about anatomically modern humans, us, our ancestors, but if one looks at our origins, we come from an ancestor that gave rise to us and Neanderthals. Neanderthals were around until 40,000 years ago or so, they were very like us, they probably merged into our population, but when did they leave Africa then? Were they also part of this exodus at 70,000 years or had they already left Africa?
Andrea - So they've actually left Africa much earlier than that, we're thinking probably 350 or even up to 450,000 years ago. So they were, in a way, one of those first expansions of the ancestors of us and Neanderthal that made it into Eurasia and they, in a way, became the specialists in the cold climates. And it might even be the explanation of why the later waves didn't really make it for modern humans because...
Chris - Well, that was going to be my question, which is, well, if they can do it, why the hell couldn't we? What was the hold-up for us that they, in some way, surmounted?
Andrea - Well, we could do it as well, it's just that we were a species that was much more specialised in hotter climates and they were the really cold-weather specialists. And so when people came out of Africa later on, they were basically not really equipped for the kind of challenges that you had in Eurasia. There was actually a third cousin, as a matter of fact, that we had contend with, because in Asia there was probably Denisovans that we know very little of. And again, they would have been probably quite able to cope with a number of the cooler environments that you find in Asia. And they were probably a barrier for us. So what we see is that us, anatomically modern humans, came out at the good times when the weather was particularly good and then we always faded when the weather got worse. And those specialists were just there in a way and they pushed us back.
Chris - And yet, when we then, by 70,000 years ago or so, learn how to become much more adept at handling these environments, those other groups like the Neanderthals, like the Denisovans, who you're saying were there first, they no longer had that edge over us. So we could exit Africa and make it after that. And then we went everywhere.
Andrea - Yeah, that's what we think. And probably we were so many that at that point, indeed, we did integrate some of the Neanderthals into us. There was a little bit of genetic material that comes from them. And so the Denisovans, but the wave at 50,000, just had a different demography. It was just a different number of people compared to what was there before.
14:25 - Runoff at US-Mexico border causes airborne health risks
Runoff at US-Mexico border causes airborne health risks
Adam Cooper, University of California, San Diego
At the US-Mexico border, coastal waters are being polluted by sewage, industrial waste, and runoff - especially from the Tijuana River. Heavy rain in this region can send billions of gallons of contaminated water into the Pacific Ocean, affecting beach communities in both nations. But now a new study has found that some of these pollutants - such as drugs, plastics, and chemicals from personal care products - actually also end up in the air, released by sea spray and river turbulence. This means that people are being exposed, even if they don’t go in the water. Here’s Adam Cooper at the University of California, San Diego…
Adam - We were investigating a decades-long sewage crisis along the U.S.-Mexico border, where millions of gallons of untreated wastewater, as well as runoff and industrial release, cross the U.S.-Mexico border into San Diego and release into the Pacific Ocean. And for the longest time, we thought that this sewage would stay in the water, but we've seen from previous studies that some of these chemical compounds and bacteria can transfer into the air. And so we set out to go study which of the chemical compounds could make their way into the air, where people would be much more readily exposed to them through inhalation.
Chris - How did you do it?
Adam - So we went down to the border, as well as several sites along the coast, and we set up sampling stations to collect aerosols onto the filter by pulling air through a pump, basically acting as if you were standing there breathing for 24 hours and collecting all of the chemical compounds that you'd be exposed to. And we also collected water, both directly from the Tijuana River, as well as the ocean along the coast.
Chris - And what then you compare, what you know is in the water, because it's in the river and the ocean water, and then what is getting into the air. So you can see what seems to be migrating between the two and in what sorts of rates and proportions.
Adam - Yes, we used a sewage tracer that we found in really high concentrations in the river. It's a chemical called benzoylecgonine. It's basically what our bodies metabolise cocaine into. And so we knew that the only source of this chemical compound would be sewage in the Tijuana River. And then so we tracked that pollutant through the river, into the ocean, and from the ocean into the air, and we compared it with the other chemicals that we saw in our samples.
Chris - Right. So the cocaine breakdown products give you a proxy marker. This is sewage, and this is how much of it there is. So you can standardise everything day to day, I presume that's why you've done that. But then you're looking at a whole range of different chemicals. So what chemicals were you probing with this?
Adam - Yeah, we tried to pick chemicals that could represent a wide range of different categories. We detected octinoxate, which is the active ingredient found in sunscreens. We were looking at other common tracers of sewage like caffeine, as well as several pharmaceutical drugs and illicit drugs, methamphetamine, cocaine, heroin. And additionally to that, we were looking for pesticides, herbicides, and dimethylbenzylamine, which is a tracer for tire wear particles. We detected all of those compounds at relatively high concentrations, both in the water and in the air. And we saw that some of the compounds would transfer more readily into the air, and some of the compounds would preferentially stay in the water.
Chris - And what do you think the mechanism is then for when these things are in the water? How are they getting out of the water and into the air in such appreciable quantities?
Adam - So the main mechanism that we expect to occur is via sea spray aerosol. Basically, whenever a wave crashes at the beach, you see the white foam form that's from millions of tiny bubbles going down into the water column where they can scavenge some of these chemical compounds. The bubbles then come to the surface and pop, and that popping can send these chemical compounds, as well as bacteria and viruses, into the air.
Chris - And in what sorts of quantities? Because you said they're there in significant amounts, but if I'm standing on that beach, it's slightly scaring me to think I'm getting a mouthful of cocaine every time I breathe in, or at least cocaine derivatives, and worse. But how much is the actual dose? I mean, is it relevant to health, or is it there at excruciatingly low levels that people like you with amazingly sensitive analytical equipment can pick up, but it's neither hide nor hair when it comes to a person walking along that beach?
Adam - We frankly don't know the full health implications of some of the concentrations we measured. For example, two of our most concentrated compounds were octanoxate, that sunscreen chemical, and methamphetamine. And these were found in the tens of nanograms per cubic meter, which is similar to what a wastewater treatment plant worker might experience if they stood directly above a vat of raw sewage. And so initially, that dose, you know, you're not going to get high off of methamphetamine, you'd have to stand there breathing for hundreds of years. But the chronic health exposures, especially for people living in this region, they're exposed to this day in, day out for decades of their life, and we simply don't know the impacts of chronic exposure, long term exposure to these pollutants.
Chris - What do you propose then is the right way forward? Is it just to say, right, well, look, this is a problem, we've demonstrated there's a risk, got to clean up our act? Or does this enable us for the first time really to start to put standards down and say, right, we can measure the air that indirectly tells us about the water, which is going to be the source, and we need to start doing something about it?
Adam - Yeah, there's so much I can talk about here. The golden rule in pollution science is source control, we need to release less pollution into the environment. And it's much easier to stop it at the source than to go back and clean it up later. And that can look like investments in wastewater treatment facilities, there's been a lot of movement from the United States federal government to invest in wastewater treatment facilities for the river itself, as well as wastewater treatment plants for the city of Tijuana. Beyond that, there are ways to reduce your exposure. Humans spend, you know, 90% of our time indoors. And so getting good air purifiers inside can really reduce your exposure to some of these pollutants. And we need to make standards. A lot of our air quality guidelines were developed in the 70s based off of smog and vehicle emissions. We're living in a different world now with microplastics in the air, all of these endocrine disrupting chemicals. And so I believe we do need to update our air quality standards to also encompass these micropollutants, which we're seeing more and more evidence is leading to really negative health effects long term.
21:23 - Non-alcoholic beers could be cause for cardio concern
Non-alcoholic beers could be cause for cardio concern
Giles Yeo, University of Cambridge
Non-alcoholic beers have gained traction in the market in recent years and are often sold as healthier alternatives to their boozier equivalents. But could it be doing us more harm than good? A new study from scientists in Germany and the US has tracked the effects of booze-free beer on a group of healthy young men. Over four weeks, some drank two bottles of alcohol-free beer a day, while others stuck to water. The results, published in the journal Nutrients, raise concerns about cardiovascular health, especially with sweeter, flavoured varieties like wheat beers. But even the lighter pilsner-style varieties weren’t entirely off the hook. So what’s the verdict? We asked our friend Giles Yeo, geneticist at the University of Cambridge where he studies the complex relationship between genes, appetite, and body weight, to share his thoughts…
Giles - I think the key things they identified, certainly what was in the title of the paper, which I went to have a look at, were lipid metabolism within the blood, so I think primarily measuring things like cholesterol levels and free fatty acids, that kind of thing, and glucose. Those were the two measures that were reported to be adversely affected, shall we say, during this experiment.
Chris - Is that when they're drinking the alcohol-free beer, or is that in the aftermath?
Giles - So what they said was, well, if you compare two groups of people, some drinking these two bottles of alcohol-free beer versus water, then the alcohol-free beer clearly had an effect on what they were measuring, so blood glucose and blood lipids.
Chris - Now is that attributable to any change in body weight? Because we know if we change body weight, if we get heavier, we become less good at responding to insulin, so sugar goes up, and blood fats also tend to do that. So is this just a body weight thing? People drinking those beers gained weight, or is there something else going on?
Giles - I think you can get these things changing without changing body weight, and I think in four weeks with two bottles of beer, I don't think they saw any changes in body weight, so they were attributing it to something beyond body weight.
Chris - So what do they think the mechanism is then?
Giles - Do you know the issue? The issue is that they compared it to water. It's like asking, is vaping good for you or bad for you? Well, compared to what? I mean, compared to smoking, it is going to be better for you. Compared to not smoking, it's not good for you. And I think the same thing is going to be true for these alcohol-free beers. I mean, look, if you are pregnant, if you are teetotal, if you're driving, I mean, for Pete's sake, drink an alcohol-free beer if you fancy a beer. But is it going to be better than water for you? No. And so I think if you have an alcohol-free beer, it will have all of the calories found in a beer minus that of alcohol, which is substantial. But you will also clearly have an increased amount of carbohydrates, increased amount of sugars, all kinds of things. So if you suddenly have an increase in that amount of calories, energy intake, then you're going to see some adverse effects, certainly when compared to water.
Chris - Do you think that a lot of these things like alcohol-free beers, but also low-calorie food stuff, are they seducing us into buying into them under the misapprehension that they're going to be better for us in some way? And in fact, they're actually translating into health harms because there've been various claims, for instance, if you use sweeteners to sweeten your tea and not your sugar, perhaps it affects the way that you then consume sweetened things at other times. I mean, is this all part and parcel of the same thing?
Giles - Within the business, I think we call it the health halo. It's the way they're marketed, and they're marketed to be more healthy. Now, the word healthy is doing a lot of heavy lifting here. What are you measuring in terms of health? And so you say things, you're right, low-fat, low-sugar, high-protein, or alcohol-free beer in this particular setting. There's nothing wrong with an alcohol-free beer, but it is a problem if you're trying to sell it as a health drink. I think that is the point. No one thinks that drinking Coca-Cola is healthy. And so we drink it and we treat it like the treat it is. So we should not take foods that are perfectly fine for you, you know, when drunk with dinner, when drunk here or there, but to sell it with this health halo, and I think it is an expanding problem. Very few things in nutrition annoy me more than health halo around foods.
Chris - Are we navigating into a sort of a nutritional perfect storm then in some respects? Because we've got these health halo foods, but then on the flip side, you've got the thing that Chris Van Tulleken's made a big noise about very successfully, which is the ultra-processed foods. So we've got convenience on the one hand, and then our obsession with trying to be healthy on the other, and you bring both together and neither are actually good for you.
Giles - I think you're absolutely right, because remember, these alcohol-free beers are also going to be ultra-processed by its very nature. You sort of have to make the beer and then strip out the alcohol or however it actually works. I just think that we should be calling a nail a nail. So what is it? It's an alcohol-free beer, and so if you fancy a beer and don't want to drink alcohol, this is the drink for you for now. I think anything else, calling it healthy, calling it unhealthy, what is the comparator? What are you comparing this healthiness or non-healthiness to? Without that figure, without that number, the statement I think is useless.
Chris - Are you an alcohol-free beer man? Because I seem to remember you went on a vegan diet for a while, and I caught you having a beer in the pub, and you said it is vegan-friendly, I seem to remember. Do you remember that? It was about 10 years ago.
Giles - I do absolutely remember that the beers are vegan-friendly. Do you know what? This is an opinion and you have to fact-check this, but I've got people who do a lot of cycling, exercise-y type folks, and what they tell me is that an alcohol-free beer is the superior, fact-check this please, recovery drink. Now, normally if you drink things like Gatorade or Lucozade, whatever the hell it is, what people are saying is compared to something like Gatorade, you get the salts and whatever it is in there, but you get the carbohydrates in slightly more complex form rather than like a sugar. So actually as a recovery drink, I can see how an alcohol-free beer is perfectly fine for you after you come back from a long cycle or a long run.
27:55 - Why might clouds move in different directions to the wind?
Why might clouds move in different directions to the wind?
Thanks to Paul Williams for the answer!
James - It's usual for the wind speed and even direction to be different at the altitude of the clouds than at ground level. This is known as wind shear. Before we get into that though, what actually causes wind in the first place? Paul Williams is Professor of Atmospheric Science at the University of Reading.
Paul - Winds in the atmosphere are generally generated by pressure differences, and I think we're used to seeing these on weather maps. In general, you might have high pressure in one area, low pressure in another area, and of course, the wind will try to blow from high to low pressure, except there's a complicating factor, which is that we're on a rotating planet, and so as it tries to blow from high to low pressure, it gets deflected to the right in the northern hemisphere by something called the Coriolis force, which is a mysterious, actually fictitious force, doesn't really exist, but we have to include it in our equations to account for the fact that we're on a rotating planet.
James - This means that in general, in the atmosphere, wind does not travel in the direction of high to low pressure, but in the perpendicular direction, bizarrely. But what's causing vertical wind shear, i.e. the difference in wind velocity and direction for neighbouring bits of the atmosphere, one on top of the other?
Paul - At the level of the clouds, when the air is moving, there is a balance of forces. We have the force resulting from the pressure difference being balanced by the Coriolis force, and that's nice and simple, and that's what sets the wind direction at those altitudes, but when we get close to the ground, there's a third force that comes into the equations, and that's associated with friction. It's called the turbulent drag, resulting from the interaction between the atmospheric flow and the surface of the earth, and that reduces the speed, and it puts this third force into the equation, and that gives us a different wind direction. So that's the basic reason why the wind direction can be different at the level of the clouds compared to at ground level. And interestingly, we have the same effect in the ocean as well, not just the atmosphere. And in fact, this phenomenon was first discovered in the ocean by a Norwegian scientist called Ritjof Nansen, who in the 1890s was on an expedition of the Arctic, and he noticed that the icebergs were not moving in the same direction as the winds and the surface ocean currents, and that sparked his interest, and eventually a Swedish oceanographer called Ekman studied the mathematics of this, and so this effect, the fact that the wind direction changes with height both in the ocean and the atmosphere, is today called the Ekman spiral, after him.
James - So Tony, your observations are correct. Wind does in fact change velocity and direction at the altitude of the clouds and at ground level, and this is known as wind shear. The main contributing factor is friction, caused by the wind bumping into obstacles like the terrain, trees, buildings and the like down here on the ground. Variations in pressure do influence the winds and can vary with altitude, though they are generally related. Thank you to Professor Paul Williams from the University of Reading for helping us clear the air.
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