Jim Yong Kim has a strong track record for convincing politicians and public health leaders to take on tough projects. As a co-founder of the Boston, Massachusetts-based healthcare organization Partners in Health, he helped overturn the dogma that curing drug-resistant tuberculosis was too expensive and complicated to do in low-income countries. Soon after, he spearheaded a similarly controversial initiative as director of the World Health Organization’s HIV/AIDS programme. It increased the number of people on HIV drugs in the developing world by six-fold in two years. In 2012, Kim became president of the World Bank, an international institution tasked with reducing poverty through loans and grants to the governments of low and middle-income countries. Kim left the position in February 2019, before his tenure ended, to spearhead an initiative to invest in emerging economies at the New York City-based firm Global Infrastructure Partners.

Now he’s put that job on hold to devote himself wholly to the coronavirus response. On 3 April, Massachusetts announced it would budget $44 million for an ambitious contact-tracing program to hire 1,000 people through Partners in Health, where Kim serves on the board of directors. The effort will involve a legion of contact-tracers, who will call people diagnosed with COVID-19, and then call their contacts. The goal is to isolate those who are infected and stop the spread of the virus. Now that Kim and his colleagues have mapped out the operation in Massachusetts, the idea is gaining traction with other states.

Nature spoke with Kim about the pandemic. The interview has been edited for brevity and clarity.

What surprised you about the response to COVID-19 in the US?

No one in the field of infectious disease or public health can say they are surprised about a pandemic. But what I just couldn’t believe was that after the first cases of community transmission in Washington, folks were saying it’s too late for containment. What surprised me is just how quickly we gave up on the standard shoe-leather epidemiology approach to fighting epidemics that has been in place for hundreds of years.

You know the great story of John Snow? All these people in London were getting sick and dying of cholera, and he did contact tracing to figure out that they were all linked to a single water pump in the city. And he removed the handle from the water pump, and the cases went away. That showed you’ve got to trace where the bug is going, and chase it down. That’s how you defeat it.

What did you do?

I reached out to Tony Fauci, who I’ve known for 20-25 years. I said, “Tony, what’s going on?” He said, “Jim, in a perfect world, we would be doing everything we should be doing, but what we’re trying to do right now is just get across the need to go into lockdown, which itself was very controversial.” So, I said, “Tony, do you think it’s a good idea for me to try to stand up a full public health response somewhere?” He said, “Absolutely. Go after it.”

I reached Charlie Baker, the governor of Massachusetts. And Governor Baker made the decision to take a chance on a contact-tracing program for the entire state. We’re going to hire 1,000 people right away, and we’ll have to spend more on isolation and quarantine. He had to make the decision to dip into the state’s funding to do this.

Do you have any tips for how scientists can have their voices heard by policy makers?

I think it’s very hard to convince others to do things that are complicated and labor-intensive, unless you’ve done it yourself, or at least started doing it. I can’t just expect someone to spend millions of dollars, to go from zero to 60 in a short period of time. You need to actually do it and say, it’s not perfect, but here it is.

That may be working. Last night, I spoke with Governor Mike DeWine of Ohio. He wanted to know what the details are in Massachusetts. So, I walked him through the steps of what is going to happen in Massachusetts now. It’s not perfect yet—it’s still in the works—but we have a programme. And then he said, “Alright, let’s do it.” Now, Partners in Health is going to work with Ohio to get this program up and running.

Do you make a financial argument in your push to contain COVID-19?

I spent seven years at the World Bank. So, I’m a finance guy. I can tell you it makes absolutely no sense to keep putting trillions of dollars into a stimulus package and not put hundreds of billions into the one thing that will stop the financial crisis. The thing that will stop the financial crisis is to get the virus under control.

We will probably get a vaccine against COVID, but we cannot stay in lockdown until that happens. The financial impact is just going to be so devastating that we have to figure out a different way.

I think a major mistake that we’re making now is that some people are assuming the curve of cases is going to come down pretty rapidly based on the Wuhan data. But the US is not doing anything close to what they did.

Are you worried about what will happen in low and middle income countries?

I’m extremely worried about what’s going to happen in most of the world. The whole financial world is turned on its head. This is clearly worse than the global financial crisis. It’s getting close to the global depression of the 1930s. And it’s possible that it could get even worse.

In low-income countries that means people will starve to death. It means aid budgets will completely dry up and there will be no aid coming in. And I hope that the global multilateral institutions are not under threat. Both the International Monetary Fund and the World Bank are hardy and robust institutions, and I hope that they’ll be able to continue lending in the midst of a crisis. But this is completely uncharted territory. It means utter disaster for developing countries.

So, this is why I’m going crazy telling people, “I’m sorry. It’s hard. It’s complicated. But we’ve got to do this right.”

What do you think about the idea of waiting for the coronavirus to saturate the population until people have either died or built up natural immunity?

If we just let everyone go out and get infected, I think the patterns we’re already seeing in differential mortality — in the African American community, the Latino community, among poor people, people who live in shelters — will continue. And you’re going to see lots and lots of people die. And some people are saying, well, there’s got to be an acceptable level of mortality. I don’t know what that is. And if there were no other option, if there was no other way to do it, well, then maybe I could entertain that kind of an idea. But there is an option! They are doing it in Rwanda. They’re doing it in Korea. They’re doing it in China. They’re doing it in Austria and Germany. This is completely doable, so why would you sentence so many people to death if you know there is another path?

This why I’m on the warpath against stopping the virus’ transmission. That’s the ultimate goal and we’ve got to use all the tools possible to do it.

Why did you abruptly leave the World Bank before your term was over?

I left because I felt that just about everything that I could personally contribute to the World Bank, I had. And I felt like the biggest challenge in the world, at the time, was to build more infrastructure in developing countries. So, I decided to join one of the most successful infrastructure investment companies, and start their emerging market infrastructure program.

I still believe that’s a huge need, but I’m now 100% on the COVID response, because the most important thing we can do now is to stop the public health crisis.