Dive into the latest trending topics in global health with IHME's Global Health Insights blog. Our health researchers explain the significance of new studies, share data related to current events, and help you understand the story behind the numbers.
December 20, 2022: China after zero-COVID
- We project over 300,000 deaths in China in the coming months, and more than a million over the course of 2023.
- Why? China has a large number of people who have never gotten COVID or been vaccinated against it, leaving them susceptible to severe illness or death if Omicron begins to spread.
- How can China manage the spread of infection?
- Eventually most people will get exposed or infected with Omicron, but the pace can be slowed to reduce burden on hospitals by increasing mask use and imposing moderate restrictions on gathering (not a complete lockdown).
- The death toll can be reduced by scaling up access to antivirals and deploying more effective vaccines, like Moderna or Pfizer.
This transcript has been lightly edited for clarity
What are the contributing factors to increases in COVID around the world?
In this week's forecasts of the COVID epidemic around the world from IHME, the critical issue is what's happening in China and how that will unfold. And in the rest of the world, there are increases in COVID in a number of countries. These are increases that we have expected to see due to winter seasonality in the Northern Hemisphere.
And it's playing out sort of as expected and is not larger than perhaps what we had expected many weeks ago. But the situation in China is much more complicated. We have been saying for the better part of the last 10 months that we don't really know what will happen in China because the critical determinant is when the zero-COVID strategy would be abandoned.
What will happen when zero-COVID ends?
It does appear now that there is a great reduction in the controls around transmission in China. And our models suggest that there will be a very large epidemic in China as those restrictions come off.
Now, the critical thing to ask in the case of China is what is the combination of a population that's been vaccinated with a somewhat less effective vaccine, or quite a bit less effective vaccine than, for example, Moderna and Pfizer; low vaccine uptake, even of that relatively less effective vaccine, in the 80-plus population; and so far, as far as we understand, no access to antivirals on a broad-based basis.
The best model for that experience is what happened in Hong Kong with the BA.1 epidemic that occurred in Hong Kong, which led to 10,000 deaths in about a one-month period.
As we look in our models – factoring in that we think when things get very bad, some restrictions will go back in – we still see that there will be greater than 300,000 deaths in the coming months in China. And, in longer-range forecasts, we expect that number over the course of 2023 to reach above a million deaths.
Why will there be so many deaths?
Well, there's this huge number of susceptible individuals because of either low efficacy of the vaccine, the vaccine was delivered quite some time ago, and so immunity has waned, as well as those who have never been vaccinated. We also know from experience with COVID that the initial wave, even with Omicron, as seen in Hong Kong in an immunologically naive group, can have quite considerable mortality.
If you think about Hong Kong, 8 million people, 10,000 deaths, and during that period you had an infection-fatality rate that was about 0.1%. And if you apply that to the whole country of China, you get some very large numbers. And that's why we do expect that the death toll will be very considerable in China.
When will the death toll begin to rise?
Well, our models suggest that we will see the current decline bottom out and then start to go back up in January.
We expect a peak of transmission toward the end of March and then a slow decline from there with perhaps continued, as we've seen in Hong Kong, transmission throughout 2023.
What are the strategies available for China to manage this?
The numbers I've been quoting reflect what we think will happen, which is, province by province, serial use of mandates to slow the transmission, perhaps reduce the burden on hospitals, but fundamentally not to change the long-term outcome because eventually most people will get exposed or infected with Omicron.
It's really a question of spreading out the harm from this Omicron wave that we see coming in China. Wider-spread, consistent mask use will lower the toll. A more aggressive implementation of mandates, as we've seen throughout 2022, could stop transmission. We just are not building into the models that there will be complete lockdown as in a zero-COVID strategy reimposed.
So grim prospects for China in the coming months. And there are strategies which have so far not been adopted, such as trying to deploy a more effective vaccine (Moderna or Pfizer) or trying to scale up access to antivirals, both of which could considerably reduce the toll in China that is expected in the coming months.
December 16, 2022: Tackling the global health threats of the future
- The Lancet has announced a new Commission to examine the broad set of threats facing the world over the rest of the century.
- Who will be part of the Commission?
- Leaders of public health institutions, global thought leaders, youth representatives, and other diverse global leaders.
- Which health threats will be examined?
- Pandemics, climate change, conflict, demographic changes and inverted population pyramids, high body mass index, antimicrobial resistance, and other prominent health threats that emerge.
This transcript has been lightly edited for clarity
This week we announced in The Lancet the creation of a Lancet Commission on 21st-Century Global Health Threats. This Commission is chaired by Natalia Kanem, the executive director of the United Nations Fund for Population Activities, and by myself, and the commissioners are drawn from a diverse set of regions and occupations. We have some current and former heads of state.
We have leaders of public health institutions in each of the regions of the world. We have global thought leaders on particular types of threats. We have youth representatives. We have some of the key leaders of global funding organizations. This diverse group is going to try to look for common solutions that cut across the multiplicity of threats that we see for the future.
There's excellent work that's been done on some of those threats to date. Commissions on pandemics, standing commissions, and other analyses around climate change. There are some, but probably less work on the role of conflict. But as we look at some of the other threats, there's perhaps less work – the threats, for example, from demographic change and inverted population pyramids and what that will do fiscally and economically and socially to many countries.
What do we do about high and rising body mass index around the world, about non-communicable diseases that go with that? What about the threat of antimicrobial resistance and its spread in the future, just to name a few of those threats. But governments and other actors in society and citizens are going to have to navigate a world of the combination of multiple threats. The purpose of this Commission is to look at the evidence and see if there are common strategies that might help societies manage that multiplicity of threats.
Looking far past the SDG target year of 2030 and into the middle of the coming century will be a two-year process. We hope to have the results published from the Commission at the end of 2024, and there will be, once the Commission has its first meeting, the creation of a number of working groups. That will also be a mechanism for hearing evidence and bringing evidence to bear on what the future might hold.
We hope to use quantitative forecasting tools as an input as well as scenario building. How can we change that future, reduce the potential harm from these threats, and have a diverse set of voices from around the world feed into what we hope will be an important and useful set of recommendations? So look forward to more coming on the Commission.
And there is also a website for the Commission, which will provide information on the status of the work as it proceeds.
December 2, 2022: Without zero-COVID, will cases surge in China?
- When the zero-COVID policy becomes unsustainable, we expect a major death toll among the 80+ population in China.
- The reason: Low vaccination rates, less effective vaccines than in other countries, and no widespread availability of antivirals.
- What can be done to minimize the death toll?
- Try to increase vaccination rates in the 80+ population, including use of more effective vaccines.
- Increase availability of antivirals.
- Until now, China has avoided major outbreaks, leaving the population largely susceptible to new infection. Higher rates of infection also increase the probability of new variants developing.
- New variants may not be more severe than past ones, as was the case with Omicron sub-variants.
This transcript has been lightly edited for clarity
High death toll expected in 80+ population
In this week's Global Health Insights, I would like to address the question of what we think is going to happen in China. During the past year, trying to model the course of the epidemic in China has been extremely challenging. When we saw Omicron pass through Hong Kong, the surprise to many was the large number of deaths in the elderly, and at the root cause of Omicron's toll in Hong Kong was that in the over-80 population particularly, there was relatively low vaccine coverage because of lack of confidence in some aspects of vaccination.
And so the question comes, what will happen in China when there is widespread transmission of Omicron? And at various points, we have predicted that this would happen in the spring or in the summer or in the fall, given the economic costs of pursuing the zero-COVID strategy.
Now, many people have expected that China would ease the policy once the party Congress was over. And again, we're hearing rumors that there may be a shift away from a zero-COVID strategy.
But the basic Hong Kong problem still exists in China: you have a substantial fraction of the over-80 population, in almost every province, that is not vaccinated. In the rest of the population, you have a vaccine that has less effectiveness than some of the mRNA vaccines that many other countries have used. And there is not widespread availability at all for antivirals, such as Paxlovid.
So we do expect that at the point, at some point in the future, when it's unsustainable to continue a zero-COVID strategy, there will be widespread transmission of Omicron, and that will actually have a considerable death toll in the over-80 population.
What can be done to minimize the death toll when the zero-COVID strategy ends?
Now, things can be done to manage this, given we do expect you can't maintain that forever, or we don't believe you can. Then the question is, can you slow the transmission and keep the burden on the health system at a more manageable level, so that hospitals are not overwhelmed?
And that's one of the options that are available, using some less restrictive, but still some form of mandates to slow Omicron transmission. There's already pretty widespread mask use, so that's not going to change very much of the trajectory.
The other strategy or option is would China change course and actually try to vaccinate, particularly the older population, with the more effective mRNA vaccines? But even there they still have the fundamental problem of lack of trust in that population with the vaccines, even the Chinese-made vaccines. And it's not at all clear that there will be enough trust to get high enough vaccination coverage to avoid the death toll in that age group.
And then lastly, is the strategy of trying to acquire and have antivirals available, particularly for that high-risk group, the over-80s.
Implications of widespread infection for immunity rates
However we look at it, it's very likely that the next few months are going to be quite challenging for China. If we've learned anything from our systematic reviews around the patterns of resistance after infection, it's that infection with different strains of the virus does induce considerable immunity that lasts, for preventing death, quite a long time, and for preventing infection, quite a long time, as long as there isn't a new sub-variant that comes along.
And in fact, our systematic reviews do show, and we expect they will be coming out more publicly in the near course, that the immunity from natural infection is as good as and longer sustained than immunity from vaccination. So put that together, it means that the populations at greatest risk in the world are those that have avoided a lot of transmission and have gaps in vaccination. And that's exactly the case for China.
Potential for new variants to develop
So there's always the concern around the large volume of transmission leading to an increased probability of new variants. And certainly that has to be true at some statistical level, that if you have billions of infections, you're more likely to see new variants emerge.
But it's not clear how big an issue that is because all the people who are susceptible in China will eventually get infected. Are we better off seeing that spread over six months, or nine months, or three months, or two months? Not clear, since risk of a new mutation, for example, is proportional to the number of infections.
The news that should make us less alarmed is that we've had billions of Omicron infections this year and yes, we have seen new sub-variants emerge – BA.2, BA.5, XBB, B.111 – but none of them have been a dramatic change. They've had some immune escape, but they have not had increased severity.
So we don't know, of course, but it's not as if having a concentrated period of half a billion infections, is really that different from having it spread over a few more months, which would happen with stronger controls on transmission.
As we look forward there's also the risk that as time goes by, the natural immunity from, for example, the huge Omicron wave that infected so many people in the world, will start to wane and we will start to see more people at risk of future sub-variants of Omicron or other variants, which could be more concerning.
And so it's not as if the only place in the world that's at great risk is China. It's just that that's the biggest concentration right now for that at-risk population.
So it's a situation for which there's no obvious solution because neither the zero-COVID strategy forever is going to work, nor is there any indication that China will try to deploy better vaccines or have access to antivirals.
And that leaves us in this situation where it's probably going to be a balancing act they pursue of trying to have transmission and having it be slower. And so that is the situation we find ourselves in for COVID in China in the coming months.
November 22, 2022: World Antimicrobial Awareness Week
- A short list of pathogens account for a large fraction of bacterial-related deaths. The main causes include S. aureus, E. coli, S. pneumoniae, K. pneumoniae, and P. aeruginosa.
- These pathogen estimates are immediately relevant to groups concerned with the development of new antibiotics and new vaccines, such as research and development investment groups, the research authorities of different countries, and private sector investors in the pharmaceutical industry.
- There may be a mismatch between R&D investment spending and disease burden. For example, $42 billion in the last two decades or so was spent on HIV, while the spend on a major bacterial pathogen like E. coli was only about $800 million. Yet the burden of E. coli is only a little bit smaller than the burden of HIV.
- Prioritizing infection prevention is important through measures such as risk management, infection control in hospitals, and deploying existing vaccines (like the vaccine for strep pneumo) more widely.
This transcript has been lightly edited for clarity
In this week's Global Health Insights, we're going back to the body of work that we started earlier this year when we published on the burden of disease due to antimicrobial resistance around the world, due to 88 bug-drug combinations. The big database that we put together on the distribution of key clinical syndromes – pneumonia, bloodstream infections, intra-abdominal infections, others. By pathogen, we have now analyzed, not looking for the resistance patterns, but just getting a deeper understanding of what the role of 33 different bacterial pathogens are in infectious disease deaths.
And that is really groundbreaking, because we tend to see in global health the burden of disease grouped by either some specific pathogens, like malaria, or syndromic clusters, like lower respiratory infections or neonatal sepsis or bloodstream infections. But by going in and looking at all the data, using the appropriate statistical methods that have been developed, to try to use all the rich data that's out there to understand pathogen distributions. What we can reveal is the role of some bacterial pathogens that are probably hidden from people's sight in the general global health discourse. So it turns out that as we look across pathogens, there's a short list that accounts for a large fraction of bacterial-related deaths. So some of the main causes there are Staph aureus, E. coli, Strep pneumoniae, Klebsiella pneumoniae, and Pseudomonas aeruginosa, but also important roles for some of the other bacterial pathogens.
Research spending mismatch for bacterial pathogens
This pathogen view is important and it's immediately relevant to those groups who invest in research and development, the research authorities of different countries, NIH, for example, as well as to the investments from the private sector in the pharmaceutical industry, in the development of new antibiotics and new vaccines.
And in fact, there have been other research that's been done that has tried to count in the last 20 years or so the spending on global pathogens. And when we compare that spend, for example, $42 billion in the last two decades or so for HIV, to the spending on some of these major bacterial pathogens like E. coli, that spend is only about $800 million. And yet the burden of E. coli is only a little bit smaller than the burden of HIV. And so I think this pathogen view of the world, or in this case bacterial pathogen view of the world, reveals that there may be a mismatch between how the R&D investments around the world in drugs and vaccines and diagnostics as well is not necessarily aligned with where all the burden is.
We also think it's important to take a pathogen view of the world for thinking about prioritization around preventing infection where that's possible through either risk management, infection control in hospitals, as well as deploying those vaccines that currently do exist, like the vaccine for Strep pneumo more widely. And of course, if we eventually do see new vaccines come through the R&D pipeline, recognizing that there is a real opportunity to reduce harm around the world.
Taking a pathogen-specific view on the burden of disease
So this focus on pathogens, in this case bacterial pathogens, comes out in our new paper in The Lancet. We do see further work in the future coming, looking at all of the pathogens together, not just the bacterial pathogens, to bring that pathogen-specific lens to the world. About a quarter of all DALYs, a major pathogen is involved, whether it's the ones that are directly assigned as underlying cause, like HIV or malaria, or the role of many of the things in this study, bacteria in deaths from some of the chronic diseases such as diabetes, where a diabetic may die from a gram-negative sepsis in the hospital.
But having that pathogen-specific view will give us another insight into the targets for intervention as well as for R&D. It also, I think, helps get a sense in different parts of the world of, we put a lot of emphasis, appropriately so, on HIV, TB, and malaria. But we probably need to pay as much attention to something that's quite neglected, like Staph aureus, that's affecting poor countries as well as rich countries.
And so I think there's a lot to be learned about a different perspective on the burden of disease that's brought about by this analysis. So expect more in our future Global Health Insights both on the sort of pathogen perspective, how does that look as we go into the future in terms of forecasting trends, given what we know is maybe some of the important changes in the disease profile in different parts of the world? And how do factors such as climate change intersect with the burden due to specific pathogens, that may actually be affected by environmental heat temperature and other factors? So more to come on these sort of evolving understanding of different drivers of burden around the world.
November 17, 2022: Global population reaches 8 billion
- We expect the population to peak in about four decades, somewhere over 9 billion, and then begin to decline.
- In sub-Saharan Africa, fertility rates remain high, so the population will continue growing until the end of the century.
- In almost all other regions, the fertility rate is below replacement level.
- Lower fertility levels creates an inverted population pyramid, meaning a greater percentage of people in the population are older.
- With more grandparents than grandchildren, there will be significant societal impacts that must be accounted for.
- Some options to address below-replacement fertility levels:
- Increase support for parents through programs like subsidized childcare and enhanced parental leave.
- Welcome migrants to solve the gap in workforce created by aging populations.
This transcript has been lightly edited for clarity
November 15th is the day that the UN is celebrating global population reaching 8 billion and that has certainly occurred sometime this year, if not in the recent weeks. And the real question for us all is what does it mean and where is population going in the world? In our assessment at the Institute for Health Metrics and Evaluation, which is part of this new Global Health Insights, is that global population will peak in the 2060s, somewhere over 9 billion, and then begin to decline.
Continued growth in sub-Saharan Africa
But to understand population and its consequences, we need to look at the world in two groups. In sub-Saharan Africa, total fertility rates and the patterns of fertility in completed cohorts of women remain quite high. In parts of the Sahel, the total fertility rate is over seven. In other parts of East Africa and South Southern Africa, total fertility rates have declined substantially and some countries are below four, and we expect those declines to continue.
Declining fertility in the rest of the world
Nevertheless, those higher fertility rates in sub-Saharan Africa mean that we expect the population of sub-Saharan Africa to continue growing right towards the end of the century. That's in sharp contrast to what we're seeing everywhere outside of sub-Saharan Africa – with few exceptions. In places like China, the total fertility rate is now down as low as 1.1, with similar numbers in Japan, in Korea, in Taiwan, and in Singapore. We've seen India, the second largest country in the world, drop below replacement fertility in the past year.
So the pattern of below replacement fertility is now the norm outside of sub-Saharan Africa. And in the course of the next generation will become essentially the true in all countries, with few exceptions, outside of sub-Saharan Africa. This could be thought to be good for the planet – fewer people, less climate stress, but it comes with other consequences that societies are going to have to manage as fertility drops to these lower levels.
And we expect from our analysis that once women are educated and have access to pursuing careers and have access to reproductive health services, they tend to want to have about 1.4 children on average. Now, of course, there'll be a lot of cultural variation in that, but it's that average number that matters because 1.4, it means that with each generation, the population will get smaller.
Societal implications of an aging population
That creates an inverted population pyramid where there are more people in the age group ahead of you than behind you. This has all sorts of ramifications for how do governments balance the books? Who pays the taxes to pay for health insurance, social insurance? Elder care? How do economies work when it's younger workers that tend to buy homes? So what will happen to the real estate market as populations go into decline?
And there's faster decline in the younger age groups than in the older age groups. There will be societal impacts when there are more grandparents than grandchildren, and the knock on effects are things that we don't fully understand. And at least for the next 50 years, countries have two options in the set that have below-replacement fertility.
How to address it
One option is to support women and having children, the number of children they want to have as well as pursue careers. And that's sort of the pattern that's been used in northern Europe. Subsidized childcare, maternity leave, paternity leave, guaranteed rights to return to your job after pregnancy. That package of interventions and that can increase the fertility rate maybe by 0.1 or 0.2 children.
So that's a benefit, but unlikely to bring you back to replacement in those societies. The other strategy, at least for the next 50 years, is to welcome migrants and you can solve your gap in the workforce. Keep the number of workers up and the tax base for societies up by having liberal immigration policies. And many countries will successfully pursue that.
Countries like Canada, Australia, and New Zealand have been pursuing that sort of immigration policy for decades, and they've managed to keep their population numbers and workforce up and/or actually increase them in some cases. Some countries are not very enthusiastic about bringing in migrants and yet have low fertility – China, Russia, many other countries. And they will face the biggest challenges, and we worry a lot in those settings that they will be tempted in some settings to rollback women's reproductive health rights as a strategy to increase fertility.
And of course, that would not, in our view, be a good thing. It would be a setback for women. And so the global community really needs to be providing solutions for all countries about how to manage the challenges of low fertility. Are there strategies that reinforce women's right to choose on their family size? Let them pursue careers that will also help reduce the sort of dramatic reductions in population size that are possible.
The impacts of climate change
In sub-Saharan Africa, it's a different story, particularly in the Sahel region, where we expect they will be the first places in the world to face climate change impacts in the form of reduced agricultural input, heat stress in some settings in the Sahel. Some localities may not be habitable anymore as the number of days above some high threshold of temperature become intolerable.
So we do expect the combination of high fertility, climate stress in the next generation to likely lead to mass outmigration from some of those settings, either north across the Sahara or even more likely south from the Sahel belt into countries south of the of that belt. But some of those countries will also be facing the impacts of climate change.
So the world needs a nuanced approach to thinking about population. The role of population forecasting and scenario building becomes important, especially as we learn more about the options available outside of Africa to increase fertility or promote migration. And within sub-Saharan Africa, the strategies are a little bit more clear. Get women access to contraception and reproductive health services, as well as enhance the education of women, which remains really quite low in some parts of the Sahel particularly. Expect more in our Global Health Insights in the future as we try to take the modeling here at IHME – the forecasting, the scenario building, and look at some of the other threats to human health and prosperity around the world in the coming editions of the Insights.
October 14, 2022: Burden of Proof
- We designed the Burden of Proof study to help consumers makes sense of confusing health guidance by assigning a star-rating to pairs of risks and outcomes.
- We reviewed thousands of studies on risks like smoking and eating red meat to determine how strong the evidence was that those risks lead to health impacts, and whether it’s worth changing your behavior.
- Five-star ratings – like smoking & lung cancer and high blood pressure & heart attacks – indicate that there is strong evidence of association.
- One-star ratings indicate that there may be no association at all, or that more evidence is needed on the topic.
This transcript has been lightly edited for clarity
This is a project that started nearly five years ago where we were looking at all the controversy in the literature, both in the media and in the scientific literature about certain risk-outcome associations. It started with diet, but there's also a lot of controversy around air pollution and controversy about other associations. And we wanted to find a way to help the public, to help research funders and to help decision-makers in government navigate this very confusing field.
Remember back to the Time magazine cover about Don't Eat Bacon a few years back. And, you know, this is happening all the time. You see one study swinging you in one direction, another study swinging you back. And so we really wanted to find a way to help everybody navigate that complexity. So the burden of proof study is our attempt to look at all the evidence that's out there on a risk-outcome relationship.
We've done this for nearly 200 risk-outcome pairs and try and figure out how strong is the evidence and to rate the strength of that relationship on a five-star scale from one star where the average interpretation of the evidence is that it's either harmful or protective. But perhaps if you take a conservative view of the evidence, there's no relationship at all.
Right through to the five-star association where there is overwhelmingly convincing evidence of the risk-outcome relationship. The key findings is that we see a really wide range of strength of evidence around these relationships from smoking and lung cancer or high blood pressure and heart attacks, which are five-star relationships down to quite a large number of relationships – many of them are between diet or components of diet and outcome – where the relationships are not very strong at all.
In fact, in the case of the one-star associations, they may simply be something that will change in the future as a new study comes along. And so the conservative view of those is there may be no relationship there at all.
I think the most surprising aspect of the findings is that there are some associations, think about red meat and heart attacks or physical activity and diabetes, that many of us took as grounded in really strong evidence. But at the end of this process of looking at the thousands of articles that we review and then coming up with this overall assessment of how strong is the evidence and risk and outcome relationships.
Some of those things that we were very convinced about in the past turn out to not have such compelling evidence behind them. If you start with the associations at the other end of the spectrum, the five-star or the four-star or the three-star associations, these are things that everybody who's concerned about their health will want to take into account and to avoid them if they're harmful and to embrace them if they're good for you or protective.
When you get into the zone of the two-star and the one-star associations, then it's going to be more about your personal risk tolerance. If you are somebody that really is risk averse and wants to avoid any possible risk to their health, you'll want to avoid the harmful one-star and two-star risks and embrace the protective one- and two-star associations.
But if you are somebody that's willing to accept some risk or that there might be risk, then you can take a more nuanced approach to how you view a one-star association. Personally, for me as an individual, I'm not going to change my behavior for a one-star associate. But I'm probably going to act on two stars and above.
So we see this burden of proof, risk, function, work, and the star rating is something that we are going to keep up to date so that the public has access to this sort of assessment on a regular basis and can feel confident that it reflects our current knowledge. And there will be or are associated online tools for those who are motivated to get into the details and see what studies are out there and how it is we've come up with our assessment around the star rating for risk-outcome relationship. So we hope this is a service to the public and will continue into the future.