What’s the shape of global health to come? Microsoft co-founder Bill Gates issued two hopeful predictions for the year 2040 today during a lecture given at the late physicist Stephen Hawking’s home university in his honor.

Spoiler alert: Gates says insights into how our microbiome works, and efforts to cut down on infectious diseases such as malaria and HIV, will make life dramatically better for wide swaths of the world’s population by 2040.

Gates drew upon his experience as the co-chair of the Bill & Melinda Gates Foundation — and upon data relating to global health trends — to support the case he laid out in the Professor Hawking Fellowship Lecture, presented by the Cambridge Union.

He recalled that he first met Hawking in 1997 when he was in Cambridge to announce the opening of a new Microsoft research lab.

“We saw each other several times over the years — both here in Cambridge, and in Seattle for some particularly memorable dinners,” Gates said.

Even though Hawking passed away last year, his legacy lives on.

“Hawking’s last book was all about asking big questions,” Gates noted. “One of those questions was, can we predict the future?”

That set the stage for the theme of Gates’ lecture. “When it comes to the future of health, I believe the answer is yes, we can,” he said.

He pointed to dramatic reductions in childhood mortality and increases in life expectancy that have already been recorded over the past 30 years. For example, the mortality rate for children under 5 years of age has been cut in half. And the biggest bulge in the curve for mortality in later years has shifted into the 80s.

“What we see is that more people in the world are living to see old age,” Gates said.

At the same time, Gates acknowledged that there’s still a long way to go.

Improved data-gathering methods help pinpoint exactly where a given strategy can do the most good. Investing more in rotavirus vaccines would have a big impact in Chad, while focusing on curbing typhoid and cholera would be a bigger priority for Bangladesh. In Gates’ view, one priority stands out: addressing malnutrition.

How to solve malnutrition

Gates noted that malnutrition and its effects are responsible for more than half of the under-5 deaths in sub-Saharan Africa. “By solving malnutrition, we’ll be able to fix one of the biggest contributors in the entire world to inequity,” he said.

The impact isn’t limited to starvation and death from wasting. Malnutrition also stunts growth, because children are deprived of basic nutrients when they need them most to build healthy bodies and brains. Today, one out of every five kids under 5 is stunted, Gates said.

“It’s no exaggeration to say that stunting is holding back entire nations,” he said.

The fact that a quarter of the kids born on the planet don’t get the right food to develop is a mind-blowing tragedy. Our growing understanding of the microbiome will make this problem #solvable: https://t.co/IUI8I6EKxi pic.twitter.com/fIf97bjwqL — Bill Gates (@BillGates) September 4, 2019

Research into the causes of stunting have pointed up several factors that go beyond mere calories. One particularly promising area has to do with the microbiome, the community of microbes that live in your gut and process the food you eat.

Gates highlighted a 2013 study that focused on twins in Malawi, where one twin suffered from malnutrition while the other didn’t. The malnourished twin tended to have a microbiome that was out of whack.

“It showed us that we should be able to fix malnutrition by changing the gut microbiome,” Gates said.

Within 20 years, scientists should be able to engineer interventions that correct misbehaving microbiomes with probiotics, or identify the foods that can promote healthy microbiomes, Gates said.

“That’s not only going to prevent malnutrition, but also help us with obesity and many other diseases — asthma, allergies and many immune system dysfunctions are triggered by imbalances in the microbiome,” he said. “So by figuring out nutrition, which I believe we will, we’ll save millions of lives and improve human health in a very broad way.”

How to knock down preventable diseases

Figuring out how to reduce the toll from preventable diseases in the developing world is the focus of Gates’ second prediction for 2040. “During the next 20 years, we’ll be able to shift our attention from just saving lives to improving lives,” he said.

Gates pointed out that in many countries, the proportion of deaths attributed to communicable, maternal, neonatal and nutritional diseases is already below 50 percent. All of the countries that are still above 50 percent are in Africa, he noted.

“Even in those countries, we will cross that threshold,” Gates said. “The reason I’m willing to predict this is that, not only will we have solved nutrition, we’ll have many other great medical advances. I believe we’ll also have virtually eliminated malaria by 2040.”

In many of the countries above the 50 percent threshold, malaria is responsible for a significant number of deaths. For example, the figure is 17 percent in Niger.

Fighting malaria has been a priority for the Gates Foundation since its early days. Gates said better mapping of public health data is helping officials target their anti-malaria strategies — for example, the deployment of bed nets or the use of insecticides — more precisely.

Gene editing is another potentially fruitful frontier. The Gates Foundation is already supporting research efforts aimed at using gene drives to stymie the spread of malaria through species of mosquitoes.

“We’re still in a testing phase,” he said. “We need to make sure that this stays within that particular species. We need to make sure that we can contain it — that we have tools that, once we put it out there, we can bring it to an end. But it is very promising that gene drives will be the key tool to help us go after malaria eradication.”

Gates said he was also optimistic about the development of drugs to “turn the tide on the HIV epidemic.” Daily doses of antiretroviral drugs have already made a big impact for HIV patients, but Gates predicted that future drugs will be longer-lasting.

“We’re looking at having either a pill or an injection that you only have to take every few months or ideally only once a year,” he said. “It may actually come in the form of an implant in your arm that’s very easy to insert or remove.”

As researchers develop better methods for HIV prevention, including a vaccine against the disease, “we should be able to knock down this disease very, very dramatically over the next 10 to 20 years,” Gates said.

Reducing the threat from preventable diseases is likely to boost opportunities for the world’s developing countries.

“It’s no coincidence that the countries with the highest percentage of these preventable diseases also have the lowest GDP [gross domestic product] per capita of any countries,” Gates said. “And so we owe it to them to work in partnership to improve their health and help lift them out of poverty. That puts them on the road to self-sufficiency.”

By 2040, the focus of public health around the world is likely to shift to chronic diseases such as Alzheimer’s, diabetes and arthritis, plus mental conditions such as depression and anxiety.

“That will be our next challenge,” Gates said. “That is the next frontier.”

At the end of his lecture, Gates hearkened back to Hawking’s legacy.

“Professor Hawking believed in the magic of science and research,” he said. “He helped the rest of the world believe in it, too. As remarkable as his contributions to the field of physics were, I believe this is his biggest accomplishment.”

After his lecture, Gates stayed on for a Q&A. Here are a few highlights:

What about climate change? “Climate change is a headwind for Africa in particular, where you have smallholder farmers. If the weather changes, it will be very inimical to them,” Gates said. “It’ll give them a lot more years where they have essentially zero production. So as we’re fighting malnutrition with new tools, we do have to face the fact that unless we also give them better seeds, they will go backwards.”

What advice would today’s 63-year-old Bill Gates have for a 20-year-old Bill Gates? One suggestion would be to pay more attention to the governmental and regulatory issues that gave rise to the Justice Department’s antitrust case two decades ago. “If I’d anticipated some of those problems, I could have done a lot better,” Gates said. But all things considered, Gates is satisfied with how his life has turned out. “It’s a little dangerous to go back and change anything, because it might not have worked out as well as it did,” he said.

What’s Gates’ favorite animal? His first instinct was to go with animals that were important food sources for the developing world. “Maybe I’ll say chicken,” Gates said. But then he settled on his family dog. “It’s not very utilitarian, but it is a joy to have around,” he said.

Read Gates’ prepared remarks for the Professor Hawking Fellowship Lecture on his Gates Notes blog — and stay tuned for a video of the complete lecture as delivered.