Gresham College Lectures

The Future of Health Globally

May 23, 2022 Gresham College
Gresham College Lectures
The Future of Health Globally
Show Notes Transcript

This lecture looks at the very optimistic picture of trends in health around the world. Childhood deaths and the diseases of young adults are falling rapidly. Scientific advances are transforming the major chronic diseases and cancer. In low, middle and high income countries, health is improving through to old age. There are some major exceptions, such as dementia, but the extraordinary advances in health over the last decades is set to continue.


A lecture by Chris Whitty

The transcript and downloadable versions of the lecture are available from the Gresham College website:
https://www.gresham.ac.uk/watch-now/future-health

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- Today, I'm going to pull together the threads of several things we've been talking about in the lectures over the last few years, and look forward to the impact of these on health globally. I've already talked about the impact specifically in the NHS, and by extension, the high income countries. Health globally is improving at a really remarkable pace now, and there's every reason, as I'll come on to, to expect that to continue. And this is due to a combination of medical science, public health, and development. The biggest change, which I'm going to talk about in the first part of this, is to diseases in childhood. And this is particularly noticeable in low income countries, because in those settings, childhood deaths have been a very high proportion of the deaths that are seen. That child mortality is dropping fast everywhere, and this is going to lead to significant and very welcome changes in global population structure. I'm then going to talk about slightly older children and young people, and then are going to talk about younger adults, people under 50, and then the people who live through the next 25 years to around 75. In each of these age bands, the health of people globally is improving, but which improvements matter depends which age we're talking about. And then finally, I'll talk rather more briefly, because this has really been covered more fully in the talk I gave on the NHS and health in the UK about some of the issues of health in older people over 75 around the world. In summary, there are some significant risk to progress, and we need to be very clear viewed about that. And there are some areas where progress has been and continues to be slow. But overall, the future looks very optimistic. Let's start with children under five, and I'm going to present the data on this in several different ways, because this is really an extraordinary story and is going to shape the world from here on in. If you look over the period 1990 to 2020, so a 30 year period, there's been a 61% decline in the number of deaths per thousand live births. and this is in every continent we're seeing improvements, and this improvement, for reasons I'll come on to, will continue, 'cause although we've made really substantial progress, we have several more things which we can do to make things better still. If we look historically, and this is a nice graphic from Gapminder, what you can see is that this real change started where I've put the arrow around about the turn of the last century, so around 1900, and since that time there's been a steady decrease in child mortality, under five mortality around the world, starting in higher income countries, moving through to more middle income countries, and now in general in low income countries. Where we are now is where I put the red arrow, and you can see that we're still dropping and there's then a projection forward, now the exact speed of the drop from here on I think you could debate, but that there will continue to be dropping child mortality in this age group, I think is extremely clear. And as you can see, we're now at a state where the probability of children dying under the age of five is really remarkably reduced, compared to where it is, and generally very low everywhere in the world. Looking at this geographically, on the left you got the map of under five mortality in 1990 and on the right in 2020, and as you can see in every continent, this has gone from darker colors where higher mortality is seen, to lighter colors. And this is now quite highly concentrated in particular countries, and in fact, as I come on to, in particular parts of those countries. If we look at a graph of under five mortality rate per thousand life births in 1990, 2000, and then in 2020, what you can see is in each of the regions and each one of these stacks of three bar charts, it is a region that has been an improvement. So this is an improvement everywhere. The biggest absolute drops are in Africa, which is the stack on the far left, comparing 1990, 2000, and 2020 in the dark colors, but there's also significant improvements in Asia and Latin America, but solid improvements elsewhere. On the right are Europe, and north America, and Australia, and New Zealand, still an improvement, and that is the place to which every country in the world is now heading. Now, I've shown this in a bit more detail in this map, because it is important to realize also that many of the countries, which have got significant child mortality still have quite varied patterns around the country. So if you look at India, for example, there are parts of India which have still some significant child mortality, other parts, where it has dropped a very long way. So it's not just by country, it's also often quite localized. By whichever measure you look at it, this improvement has occurred everywhere. Now it's important to think why this is the case, because it both explains why we've had this extraordinary turnaround, but it also gives us some feeling about is there further still to go? To start off with two of the most important things which drove a lot of child mortality until recently, and still do in some areas, sanitation, clean water, and safe disposal of the feces, and malnutrition. Both of these are improving, if you take the globe as a whole, but there is still a way to go. So there are still big advances that we can make in these areas. So starting with clean water and sanitation, and this really drove a lot of, in particular, the fecal-oral, diarrheal, and other diseases. The provision of clean water has been improving and as has sanitation, and this has led to a substantial drop in fecal-oral diseases everywhere, but there are still over 2 billion people who lack access to safe drinking water, and there's still a lot of progress needs to be made in sanitation. The bad news is that's still the case, we must do something about that. The good news is that as that happens, child mortality will drop further. One of the good things about improvements in sanitation and safe water is that, with a few exceptions, once progress is made, things don't tend to go backwards, except in major disasters, such an earthquake or a war. Undernutrition, children dying of hunger, of undernutrition stunting, undernutrition of a variety of different types has also fallen, but there's still significant amounts of undernutrition, and the map on the right shows this, the steady improvement there's been in undernutrition. But as you can see, there is still some way to go, again, as countries become wealthier, as families get wealthier, as food is more widely distributed, this will continue to improve, and child mortality will improve further. There are, for this one, some backward pressures, of which the most important in the last two years has been COVID 19, which has interfered with many aspects, ranging from agriculture through to feeding programs. And very tragically, the war in Ukraine will exacerbate some of these problems. So those are two of the major things, the next large group of diseases, which have been steadily improving are the vaccine preventable diseases. So again, these are large numbers of infections, and so I've just given two examples just to demonstrate quite how powerful these vaccines against childhood disease are. On the left, Hib, a vaccine against a form of meningitis that's common in children, or used to be common in children, and on the right, rotavirus vaccine against diarrheal diseases. In both cases, these are UK data, it's simply 'cause we got clean data, it's easy to actually see how the effect occurred, where the blue arrow is, is where the vaccine was introduced, and you can see an extraordinary drop away of those diseases, which are threatening the lives or the disability rates among children. These started in high income countries, but are now deployed worldwide, although of course there are places where they're not, sadly, available. If you add together all the vaccine preventable diseases, and I did a full lecture on vaccine, so I'm not going to go through all of them, you can see that they make up still quite a significant proportion of childhood illness. And as vaccines are rolled out to places where vaccines are still not available, we will get further gains from vaccines as a protection of children under five. So if we just take an example, pneumonia, a infection which is passed on generally by respiratory transmission has decreased an estimated 37% just in the period 10 years between 2005 and 2015, and a lot of this can be explained by vaccines, particularly pneumococcal vaccine, but others as well. And in blue, you can see on this graph, anywhere that's in blue has had a significant reduction in their rates of pneumonia, the darker the color, the bigger the change. So these changes have occurred almost everywhere. There are very small number of countries where that's not true. So those are water and sanitation, the fecal-oral diseases, the respiratory diseases, some of the vaccine preventable diseases. Then there are the vector born diseases of which the most important in children is malaria. This is still with us, it is still killing, sadly, over 600,000 deaths a year, 77% of which, so the great majority, are in children under five. The sort of two bits of good news, overall, the geography of malaria has steadily shrunk over the last hundred years. So the number of countries where malaria's a big problem are many fewer. And particularly over the last 20 years, deaths have over halved, and there was a really very steady reduction over the first two decades of this century. Unfortunately, a combination of biological factors, particularly insecticide resistance, which reduced some of the effects against mosquitoes and some drug resistance pushed against that, an improvement, and the disruption that COVID 19 caused to control programs has also led to some backward pressure. So we have in fact seen some increase in malaria for the first time for a while over the last two years, but hopefully this can be reversed again. But this, again, is a remarkable achievement against one of the great diseases of childhood. And there are many other, but I'm just giving these examples of the things which have, stacked up together, issues around nutrition, issues around infection, in particular, have led to really substantial improvements, and what you can see in this graph, which just shows a selection of countries, they happen to be ones with which I've been associated with in various points, that these are countries which have actually all had decreases in their under five mortality, and they are converging on a very similar spot over time, obviously starting from very different places. So this convergence on much lower mortality in children under five is occurring and occurring still. Now within the childhood diseases, there's one area in children under five where the risk is greatest and the progress has been slower, and that is in the neonatal period, which is the first four weeks after a child is born. And if you look at the proportion of deaths in children under five, a very high proportion are in the first four weeks, and those are the ones that are in yellow in this chart here. Now it's not that neonatal mortality, which is here shown in yellow, in some UNICEF data in terms of mortality since 1990, it's not that that's not getting better, it is, it's improving, but it is falling at a much slower rate than the other causes that I've talked about of children who reach their first four weeks, and then in the next period up to their fifth birthday. And therefore, because the rates of under five children after the neonatal period is falling really fast, neonatal period is falling slower, neonatal deaths are an increasing proportion of the children under five, who should be alive and well, but are tragically dying at the moment. Now we know how to reduce neonatal mortality very substantially. In high income countries, you would expect to have maybe less than three per thousand live births. And you can go down from that in places with high end facilities. In low income countries, that's closer to 25 or 26 per thousand. And what that means is that there's a very long way we could go in terms of improvement, using existing science and technology. Now a few of these are really high end things, but very many of them are things which are amenable to us improving them, including pre-term birth, including caused by some infections. Birth asphyxia, an inability to breathe at birth. So this is around birthing processes and infections, which often occur shortly after, or at least appear, shortly after birth, along with birth defects, some of which are preventable. These are leading cause in neonatal deaths, and we have things we can do about all of them, many of which can be used virtually anywhere in the world. So most of these neonatal deaths should be seen as preventable, of course, it'll never be none at all. Now the reason I've concentrated so much on children under five is because they contribute so much to mortality in people under 60. And here, what we have is five year bands, under five is the left hand band, and then five year breaks from there on in. The first two, first three, rather, children and young people, 15 to 19, and then the blue bar, the period 20 to 50. What you can see in this is several different things. The first of which is the extraordinary predominance of deaths under five. If you survive to five, you are not just likely to get to six, it's not just slightly delaying mortality, you have a very high chance of getting to 60. So getting people through that first five years is really important because the next period of life, mortality rates really are much, much lower, probability of people dying is very low in virtually all settings. And you can see this, that the rates are incredibly low and you really only reach the kinds of rates that you're seeing in the under fives once people get above 65. What this has led to is that there's a shift. So in this graph, what we've got is a very similar graph to the last one, but in red, we've got the situation in 1970, in blue, the situation in 2000, and in green, the situation in 2016, relatively recently. Now what you can see is firstly, the first bit of good news is there has been a, as we've said before, a massive reduction in child deaths under five. The second is that we're seeing falls in mortality in children and young people and in young adults. And you really are now only seeing significant increases in the later stage of life. So if people survive their first five years, they will usually live through to much later in their life, generally past 60. So we're therefore seeing quite a significant shift in the pattern of mortality around the world, and this is not going to reverse. So this change, now it's been made, is a one way door, and a very welcome one. And towards the far end, you've got people in their 90s, and here is where you are starting to see increases in mortality. But that's because these are people who would've died earlier in other places. So that's good news. And I think an important secondary bit of good news on this is that there used to be a real worry, and a perfectly rational worry, that if children survived and there were large numbers of children surviving, this would lead to just some extraordinary expansion in the world population, and this would essentially carry on until it was limited by resources. This was an idea first put forward by the Reverend Thomas Malthus, Malthusianism, and perfectly respectable argument. But the data demonstrates that in reality, this is wrong. And although many people still actually believe this, that children not dying is a good thing, but it'll lead to massive problems. I think this is a misunderstanding of the data. It's now pretty clear that in places where there's reduced child mortality, widely available contraception, the second thing which the medical side can contribute, female education, and reduced poverty, really important, the result has been a very rapid drop in global fertility. So to maintain the population at a stable rate in any country, in any society, if you have a rate of 2.1 children per woman of childbearing age, that will lead to broadly stable population, anything more than that, the population will increase, well at least the numbers will increase, and anything less than that, numbers start to fall away. Global fertility around the world as a whole is now down to 2.5, so it's still a bit above that 2.1. In high income countries, I'll come on to this, it's now dropped below that replacement level, in Europe it's around about 1.5, depends which country you're talking about. And so we've seen this real transformation as a result of children not dying, contraception, female education development. From the situation on the left, where everything in red or orange, populations were increasing in the 1950s, to the situation on the right, with the same color scale, everything in yellow, pale or dark, then populations are stable or falling. And the number of parts of the world where populations are still increasing is now becoming more and more concentrated in these small number of countries. But in east Asia, increasingly in south Asia, in Latin America, north Africa, a variety of other places, rates have really come down very substantially, and in fact, come down in many parts of Africa as well. And the result of this is that if we look over the next few decades, the UN Population Division projects that global fertility will drop below the replacement level sometime in the next few decades. Exactly when will depend on a number of different factors. Once that's happened, it is very unlikely to reverse. Now of course, populations then continue to grow, 'cause people are living longer, those people who would've, you know, many people are living for a longer period, but there's a limit, and once you get to the point where the number of children being born per mother is dropped below 2 or 2.1, then you're going to get to a situation where the population stabilizes and probably then starts to fall. So people being born today may well for the first time in history, see, not only the rate of fertility dropping below replacement levels, but actually the human population of the globe stabilizing, and then probably beginning to fall. This is an extraordinary transformation. And alongside this has been a real change in the geography of ill health as you go through the later part of life for adults. And if you look at life expectancy at birth, again in 1950, on the left, and in yellow or orange are the life expectancy being under 50. In green, it's 60 to 65. In blue, 75 to 90. And if you compare 1950s to 2020s, what you can see is everywhere in the world has really transformed. And much of, for example, Africa, or resource poor parts of Asia, or Latin America have rates of mortality, or more accurately, life expectancy, which is as good as or better than north America, Europe did back in the 1950s. So there have been improvements everywhere, obviously people are starting from slightly different bases. So I talked about children and that the big change I've just shown there is largely because children are not dying. As I said, once people have got through their first five years, there's a very high chance they will get through to their 60s or later. Now of course there are risks in young adulthood, but the physical health outlook for young people and younger adults is, which I'm classifying for this purpose as under 50, medically that's what I would see as younger, is getting better almost everywhere. So in the period between 5 and 50, chances of dying for most people are extremely low. Historically, infections would've had a big impact, things like TB, cholera would've killed quite significant numbers. These have largely gone away due to better sanitation, nutrition, and medical treatment. HIV and a number of other infections, which are required after sexual debut, sexually transmitted infections, like the virus causes cervical cancer, viruses can cause some forms of liver cancer, acquired an early adulthood, but HIV being the big one, are now improving. HIV mortality rates are dropping due to treatment, hepatitis B and cervical cancer rates are going to fall due to vaccination. But we've seen a situation really transformed, and the chances of young adults dying of infections are really substantially reduced over the last few decades. In terms of the classic, non-communicable diseases, cancers, cardiovascular disease in particular, that can kill people, with a few exceptions, such as the very earlier cases of breast cancer, which usually peaks later in life, some of the lymphomas, cancers are pretty rare in this age group or very rare in this age group, as our fatal heart disease, strokes, it's not that they don't occur, but they're extremely rare in people under 50. There are, of course, some important diseases that can have an impact on life without necessarily causing mortality. Diabetes is an example, and that's an increasing problem, which I'll come back to, driven by obesity, asthma, for example, maybe going up in some areas. So I don't want to imply that everything is getting better, absolutely everywhere, but overall, the fatality rates are already naturally very low in young adults and are falling. The big risks in this age period tend to be accidents and injuries. And the leading causes of mortality in this age group include road traffic accidents, accidents at work where, you know, for example, scaffolding falls on people, accidental poisonings, suicide, and homicide. Now the first two of those, road traffic accidents and accidents at work can be significantly reduced by state action to ensure that there are safer cars, safer roads, in the case of road traffic accidents, driving tests, for example, and also that there's legislation to ensure safety at work. And in high income countries, rates of deaths on the road and rates of deaths at work have fallen steadily over the last decades. But therefore a gap is, and on the top, what you can see for example is the number of deaths caused by road accidents in the UK, right back to the 1920s. And as you can see, there's been with some ups and downs, a steady decline over the last few decades. And what we now have is a situation, rather nice graphic from "The Economist" using data from elsewhere. What you have is in very low income settings, road traffic accidents tend to be lower, 'cause there are many fewer people who got access to road transport, and in high income countries, road traffic accidents tend to be low because of a combination of safety features both in the car, the road, and the regulations. So the big risks here are in middle income countries. One important area of health, however, is a particular risk in this period, and that is the first arrival of significant mental health disorders. People may have them lifelong, but young people and young adults is where the first presentations very often occur. And this is already important and becoming increasingly important. As physical causes of illness have decreased, the relative importance of mental health illness is increasing and we've had much less progress in turning around either preventing or treating quite large amount numbers of mental health disorders than physical ones. That's not to say there haven't been improvements, there definitely have, there have been some quite significant improvements, but they have been much slower, and therefore the relative importance of mental health disorders has increased. And if you look on the right, what we've got here is the peak age at which people are first diagnosed or first present with mental health disorders. On the left, these are things which tend to peak in mid-teens, for example, anxiety and fear related disorders, feeding or eating disorders, and on the right, personality disorders on the top, schizophrenia and psychotic disease on the bottom. And what this demonstrates is that these tend to first present in young adults. So this is a period of life where we need to think really seriously about how we can prevent and treat mental health disorders. Moving back to things which actually cause physical illness and deaths in large numbers. If you look over time, and this I think is probably obvious to people, but it's worth stressing, in red here, what we have is this is an age chart of when people die and what they die of. In red are infections, neonatal, and nutritional disorders. And deaths in red, which go up to about 10, are heavily dominated by infections and nutritional issues. In young adults, really the number of deaths is very small, there are contributions from various areas, as I've said, including accidents. But then once you get to middle age, which I'm going to define as over 50, you start to get cardiovascular diseases, strokes, and heart attacks, and cancers increasingly are an issue, and they get a greater and greater issue till you get right into your late 80s. Now, if you look at the world, roughly as it is at the moment, and these are data from Hans Rosling's group, Gapminder, this is every country on the world with its income along the bottom axis, and life expectancy in years along the left hand axis. The ones in blue are from Africa, from red are in Asia, and yellow are from Europe, green, the Americas. And what is extraordinary about this is firstly that these all line up along a straight line, demonstrating that as countries get wealthier and almost every country not actively at war is, over time, not in any given year, but over decades, getting wealthier, mortality rates go down or more accurately, life expectancy goes up, and countries are all moving from bottom left to top right. Now I've put two arrows on this. Under 50, really very few countries got life expectancies now are under 15, basically almost none. Then you've got the range 50 to 75, and in this age range, cardiovascular diseases tend to play a very large part in mortality. And then towards the upper end range of this, so 70s onwards, you continue to get cardiovascular diseases, but cancers become increasingly dominant in terms of mortality, but cancer and cardiovascular diseases in some combination. And right at the top, we tend to get mixtures of diseases, which I'll come on to. If we look over time, and this is an obvious point in a sense, there's been an improvement across the world. This is the same graph, slightly different axis, 1922, so 100 years ago, and 2021, last year. What you can see with both of these is in a hundred years ago, most countries in the world, under 50, dominated by infections, and richer countries, 50 to 75, would've had a loss of cardiovascular disease, some infection, and cancers. We're now in a situation where infections are much less important as a cause of mortality or every country in the world, pretty well, is over 50. And the wealthiest countries are over 75 and have a combination of different diseases, which can be problematic. But cardiovascular disease tends to dominate in that middle period. And you can see this here, just taking the UK as an example of a country that went through a transition between 1911 and 2012. So this is again, is a 100 years of data from the ONS, and in the solid line is circulator diseases, heart disease and stroke. And blue is in men, red is in women. Dotted line is infections. Infections really fell away as a cause as the country became wealthier. Cancers have gone at a fairly steady rate over that time, and they're mainly in oldest people, But circulation diseases, heart disease and stroke, steadily increased, really through to the 1950s and 60s, and then started to improve. This pattern is likely to be followed for many countries as they industrialize. And we're now in a situation in the UK as a high income country where rates of heart disease and stroke have fallen very far. So this is data from the 1970s through to very recently, British Heart Foundation data, there's been around a 73% reduction in that time. Men more than women, some of the difference explained simply by smoking. This has been even more marked if we talk about people under 75. So this is people in their first 75 years, the chance of dying in a high income country from heart disease are now very low, not zero, and even lower in women. And there's also been a significant improvement in strokes. So circulatory diseases, which go up as infectious diseases go away, as a cause of mortality, have then come down. And this pattern has been repeated in many other highly industrialized countries over the last few decades. Other countries are still going through this transition. So here, for example, is India, of course, there's very wide varieties. India's a very large country, a very large population, but what you can see is in blue and red, the trend line for ischemic heart disease in the UK, from an academic study, and in green to measure two different ways, but the trends weren't important, what we've seen in India. And India has not yet got to the point where there's steady improvement in heart disease is yet occurring, but it will. And the reason it will, and thinking particularly about those under 75 happen, is it's due to multiple incremental steps. And most of these are widely available to middle income countries and certainly to high income countries. They include reductions in smoking, smoking drives a lot of this cardiovascular disease, unfortunately, wholly preventable. Air pollution, which is a significant risk for heart disease and stroke. A range of drugs, statins, antihypertensives, beta blockers, ACE inhibitors, aspirin, these drugs are now all very cheap and are available everywhere. So for middle income countries, these are available, provided people can be screened or can be detected as being at risk and treated. Then slightly more expensive, but actually still manageable, clot-busting drugs, drugs used when people have had a heart attack. And the first one really that moves into a situation that needs a relatively well resourced health system is cardiac stenting and cardiac surgery, something I'll actually be talking about in the next years lectures. So all of these will improve, they'll improve either because the risk factor goes down, we will see reductions in air pollution and hopefully in smoking in most countries, or because the health service can start to use them effectively. And as the country develops, that will be increasingly true. Working against this, so slowing this progress down, rising obesity, really significant problem, and consequence diabetes, and sadly, in some countries, still increasing in smoking. So those are drivers of cardiovascular disease. When it come to cancers, if people get cancer, mortality has dropped very significant in high income countries now for very many of the cancers. And on this, what you can see is the change from the left hand to the right end of this arrow, for multiple cancers in 10 year survival, using the UK as an example of a high income country. So really significant improvements in many of these cancers. As countries get richer, they will have access to this science and we will improve on the science. So the ability to actually treat cancer will spread. And cancer treatment is continuing to improve for the great majority. So just taking in the UK, the commonest cancers in men and women, as examples of these, on the left, prostate cancer, on the right, breast cancer, survival has been steadily improving, till we get to the point where the great majority of people with both of these cancers will survive 10 years and more, and have a good quality of life. So the outlook for cancer, really transformed. These sciences will be transferred, are already being used in some settings, but will increasingly become the norm everywhere. There are, sadly, some exceptions, of which by far the most important is lung cancer and a number of other cancers and diseases of smoking. The long term outlook for lung cancer remains extremely poor, even in high income settings. And sadly, smoking contributes massively to this avoidable, mortality and morbidity, lung cancer, virtually all of it, not absolutely all of it, and a very high proportion of heart disease, stroke, and other cancers. And as people are living beyond 50, because outlooks look a lot better, the impact of this public health disaster of smoking will become increasingly clear. Now in many countries in Asia, as in Europe and north America, smoking is falling, but there are some in Asia where it's not, I've highlighted here, for example, Indonesia, and there are certainly some countries, particularly in Sub-Saharan Africa where smoking rates are in fact increasing. So pushing back on the tide of smoking is one of the simplest and most cost effective ways we can help to ensure that the health gains that we've had in the high income countries can be more quickly realized in low income countries, and it costs nothing. So smoking is one very, very big and preventable risk. The second more difficult issue, but important to tackle is obesity. This is going up everywhere in every country, pretty well, certainly in every region of the world. These are global statistics from the mid '70s to recently, looking at all the different continents. So this is an increasing problem in both men and women everywhere. And if you look at a map on the left of those classified as obese, that's a BMI of over 30, you can see a really substantial change in every country of the world. In general, the higher the income, the more that the obesity happens, and as countries get wealthier, obesity rates go up, and that's certainly what we've seen in Europe, north America, north Africa, quite large parts of the middle east, and worryingly, we're increasingly likely to see in south Asia, Latin America, and Africa. So this is something which we really need to work out how we can move to a situation where improving development, incredibly important to happen, doesn't inevitably lead to significant increases in obesity. Infections, there are also some potential backward pressures on these improvements we've seen. So antimicrobial resistance against bacteria, against parasites, against viruses, indeed against fungi, threaten some of the advances we've made, 'cause a lot of the improvements we've seen in infections have been caused by good access to these, and insecticide are important for insect transmitted infections, such as malaria, and we're getting insecticide resistance, which threaten our gains. So resistance threatens some of the gains we're seeing, but again, science and rational use of these can slow down this risk and find us countermeasures. And I think it's important to acknowledge the very significant long term effect, and in some parts of the world, already quite significant short term effects, climate change is having as a backward impact on health. So all these improvements in other areas, but this is definitely going to go backwards. They range from very direct things, such as heat stress, slightly more indirect things, such as flooding through vector borne diseases, and then issues such as changes in agriculture and economy of more marginal societies. So this is another backward pressure, but nevertheless, despite these, the outlook for the health of people aged 50 to 75 and indeed, from childhood through to 50, is going to improve in the great majority of countries. Now, the result of this is that mortality is increasingly concentrated by age. And just taking the UK as an example of a country, which has evolved from low income, to middle income, to high income by current nomenclature, this shows over a period since the 1850s, when in someone's life they were likely to die. And what you can see in this graph is that on the left hand side, the lower ones are the 1850s, 1870s, and in red, 1900, obviously a very significant number of children would die before they reached their fifth birthday, in fact, in the neonatal period. But there was still a high chance of dying all the way through adulthood due to infections, accidents, and so on. As those have reduced, the probability of someone who gets through their first four weeks, surviving through to their 60s, and then subsequently 70s, has gone up really very substantially, very few people will die now between their 4th week birthday and their 75th birthday. And so the age at which people are dying in our society is increasingly concentrated in the period 75 to 100, and actually really in quite a narrow range of that, mainly after 80. And this is my final section, really, having talked about really very clear good news in children under five, really clear, low risk in children and young people under 18, also improving, low risk and improving in the young adults up to 50, and in what I would consider medical middle age, from 50 to 75, significant improvements in cardiovascular and cancer deaths in particular, but many other things. We now reach older age, which we hope everyone will reach, as a result of the improvements in the younger stages everywhere in the world. And I want to start off with a very clear statement that the outlook for individual conditions, such as heart disease and cancer is really improving in people over 75 and will continue to improve. So the outlook for health for individual diseases is really good. And because older people are at higher risk, in fact, many of the biggest benefits of the improvements we've seen in medical science are in this age group. We also have a number of degenerative conditions, they may not kill people, but they're very debilitating, such as hip arthritis, which we have very good treatments for. So things like hip replacements, just as a relatively straightforward example can be transformational. And these improvements, which are currently quite concentrated in high income countries or high, middle, or high or richer people in other countries, are going to steadily disseminate as countries become wealthier. So these are all really positive trends. This improvement would be a lot faster, in fact, than it was in the currently high income countries, because a lot of the medical science can now be banked. It's already there, we'll continue to improve on it, but what's really limiting many countries is their ability to afford some of the changes, not whether the science is there in the first place. So as development occurs, they will to move very rapidly through to getting the medical benefits of these scientific improvements. But there are, however, some diseases of old age for which we currently do not have good treatments, and an important example, one of the most important ones are the dementia of old age, Alzheimer's disease, Lewy body dementia, vascular dementia. And because people are not dying of other things, heart disease, strokes, cancers, infections in earlier life, people are living long enough to get these. It's not that the rates themselves are going up, in fact, if anything in the UK, the actual rate is probably going down, but the number of people who are living to the point where they get dementias are steadily increasing, and therefore the number of people living with dementia will increase in the UK. And this is therefore likely to occur, it is already occurring in high income countries, and it's likely to occur in all countries as they develop, and fortunately citizens can live to what would historically be seen as a good old age. There is also a problem which medical science is not adequately really addressing, and that is in old age, individual chronic conditions accumulate. So this is a graph on the right, it's well known one from the UK. People live fortunately for much of their life, usually disease free or with very trivial diseases that don't interfere with their life, but they then start to accumulate them. So they may only have one disease or chronic condition at the age of, let's say, 65, but they might have 6 at the age of 85. So increasingly we are going to have populations with preponderance of older people with multiple conditions simultaneously, which may on the first site, at least, look as if they're unrelated to one another. And this is a problem, because medical science and organization is basically designed around single diseases. We're very good at treating heart disease, or a particular cancer, or a particular infection. What we're now having to help is maximize the quality of life for people with potentially multiple simultaneous chronic conditions. And then this moves further down from several diseases to people being very frail and eventually often becoming quite dependent. And there is much less clarity about how science will develop in this area. I am confident that science will improve in this area, I'm absolutely confident about that, but whereas there's a really clear line of sight about how things are going rapidly better in many cancers, cardiovascular disease, and infections, in this area, I think the future is less clear. And finally, there is a societal question, this is not a medical question, how we support people in older age, because in every society now, the great majority of people will reach older age where they become frailer. This is a societal question, at least as much as is a medical question. And the answer to that may well vary by society, but every society is going to have to wrestle with this, and fairly soon. Almost every country is now moving to a situation where the majority of their population will reach older age and an age where frailty or more degenerative diseases become common. But I'd like to return, really, to my optimistic starting point. Global health is improving at a really remarkable pace, due to the combination of medical science, gradually accumulating, don't go backwards on that, and development. Child mortality, which I talked about a lot at the beginning is dropping very fast. Slower improvements in the neonatal period, but they are improving, but we need to concentrate very heavily on that. If people get through their first five years, their chance of living through to beyond 50 are incredibly good in virtually all parts of the world. Health of adults under 50 is already very good, and steadily improving everywhere. The health of those in the 50 to 75 kind of band is also improving, but there are some risks that we really need to counteract, such as smoking and obesity. And these are predictable problems, and for countries that don't have large amounts of either of those, the key thing is to stop them acquiring them as they transition through to the high income future, which we hope they have. More complicated areas, longevity in older people over 75 is improving, that's excellent. We're dealing with many diseases and allowing people to live, which all of us want to, to a good old age, free from many major diseases, but disability, frailty, are still things that I think we have some way to go to be clear what the future holds. So we should recognize the extraordinary triumphs, the fact that this is irreversibly changed the shape of the world, that what our grandparents were born to will be completely different to what our grandchildren will be born to. But there are also limits to medical science, and we need to think very seriously about how we support the oldest, which is where, in every society, we are going. Thank you very much. - Well, this is, very sadly, professor Whitty's final lecture as the 38th Gresham Professor of Physics. He will be returning to the college next year as a visiting professor, but I just wanted to say a few words of thanks at the end of his tenure of the professorship. I think it's safe to say that no Professor of Physics in the last 426 years since the first Gresham Professor of Physics has had to contend with the challenges that professor Whitty has. He continued with his Gresham lectures alongside his considerable duties as Chief Medical Officer during the COVID 19 pandemic. His commitment to public education and outreach is such that he even provided an additional special lecture on COVID in April, 2020, and this has had nearly 200,000 views. He still practices as an NHS consultant physician at UCLA and at the Hospital for Tropical Diseases. And before coming Chief Medical Officer, he was Professor of Public and International Health at the London School of Hygiene and Tropical Medicine. Professor Whitty's tenure as Professor of Physics at Gresham College began in 2018. His first series of lectures was on Infectious Diseases: The Oldest Enemy. This provided an overview of how these diseases have dominated medicine and mortality in the UK, and how they remain a threat as a result of widespread travel, antimicrobial resistance to drugs, and changing demographics. The series began with a lecture on epidemics and pandemics in October, 2018, and this has now been viewed over 150,000 times. His second series began in 2019,

this was Cancer:

A Fight We Are Steadily Winning, with accounts of various types of cancers and the developments in their treatment. In 2020 to '21, he presented lectures on major debates in public health, including talks on the role of the state, vaccination, obesity, and screening. And this was followed by his current series on infections and their roots of transmission, including accounts of respiratory roots, insect vectors, sexual transmission, food and drink, and touch. Well, we are so grateful to you for your incredible efforts to communicate the science of medicine to a wide and diverse audience, particularly at a time when misinformation and disinformation were proliferating. Professor, your lectures have provided and continue to provide an authoritative source of information. We at the college are most grateful to you for everything you have done, and we look forward to welcoming you back next year as a visiting professor for your series of lectures, being on the subject of diseases of the heart. Thank you very much.