Dr. Emily Wroe started working for Boston-based Partners in Health, the renowned global health nonprofit, while still a Harvard medical student. She worked with the government of Rwanda to build a modern hospital in the country’s poor northern region, perched on a terraced hilltop surrounded by subsistence farms. Later, in Malawi, she treated patients with tuberculosis and HIV, working with community health workers to track down sick patients by foot and, sometimes, motorbike.

Now she’s building a new squad of public health workers. Only this one is based in Massachusetts and it’s a virtual one, 1,000-people strong. Their mission is to track down every person in the state who comes in close contact with an infected person and help them isolate, thereby slowing the spread of the deadly virus.

And this time, the tracking will be done by telephone.

Wroe is part of the Partners in Health team charged with creating the state’s ambitious contact tracing program, which Governor Charlie Baker announced earlier this month. The administration, which has allotted $44 million to the program, sees contact tracing as a key piece of its plan to eventually open the economy up and allow people to venture out again, without fear of infection.

“It feels very similar,’’ Wroe said, comparing her current project to the public health work she’s done the past dozen years in Africa with PIH. “Because you’re taking a complex problem, where there’s a scary amount of risk for people [particularly in vulnerable communities] and you just have to start, and believe that it’s possible.’’

Massachusetts — which is testing more people than most states — is the first in the United States to launch a contact tracing endeavor of this scope. The Baker administration has gotten so many requests for advice from other states on setting up similar programs that officials have teamed up with the National Governors Association to provide an hourlong webinar on the project next week.

“We’re trying to be innovative. We’re trying to get ahead of the virus,’’ said state Secretary of Health and Human Services Marylou Sudders.

Resumes flooded in as soon as the tracing program was announced; Partners in Health has received roughly 25,000 applications in less than a month.

“People really want to help,’’ said Wroe. She signed on to the effort about 36 hours after landing back on US soil, catching one of the last flights home from Johannesburg, where she was working for PIH. She and her 5-year-old German shepherd, Bwenzi — whose name means “friend’’ in Chichewa, a native language of Malawi — are now settled in with her aunt and uncle in Byfield.

Less than a month later, more than 700 new hires have gone through the training program designed by Partners in Health, all by video of course. A contingent of the new contact tracing corps began making the first calls April 12, as part of a “soft launch.’’ So far, the endeavor has reached out to more than 4,500 people, patients and their contacts.

That number will rapidly increase in the coming weeks, after the program goes live May 1, officials said. That’s when the complete staff of 1,000 will be set up in the state’s virtual call center, trained and ready to scour Massachusetts for everyone exposed to the virus.

The concept crystallized in a late-night phone call between Baker and Dr. Jim Yong Kim, one of PIH’s cofounders and the former head of the World Bank. Baker wanted to know how to go on offense against the virus, instead of “just huddling up,’’ he said in an interview.

Looking around the world, it seemed clear “you needed some way to run at the virus and contain it if you were ever going to start to think about how you could carefully and cautiously try to help people get back to work,’’ Baker said.

The governor recalled sitting in his car, parked on the side of the road, as Kim told him that people couldn’t hide from the virus forever, and that “the only way you can run at it and contain it is to put some sort of program in place that builds on this idea of testing and tracing.’’

It’s what many countries in Asia were doing, and it’s what PIH did to successfully battle infectious diseases such as Ebola and Zika in some of the poorest places in the world, Kim explained.

“Honestly, I was sold,’’ Baker said. He asked if PIH could help Massachusetts implement a program, preferring to work with an organization that has done this before. “We’re working on a method here that is not a theory. It’s been done, and been done well in many other places.’’

Contact tracing will work only if there’s widespread testing, another prong of the state’s plan to beat back the virus that the Baker administration says it’s working on. As of Saturday, 226,845 people had been tested in Massachusetts, according to state data. The state’s testing rate per million people ranks as one of the highest in the country.

Dubbed the Community Tracing Collaborative, the program works like this: Every time a Massachusetts resident tests positive for the coronavirus, the results are shared with one of the team’s case investigators via a secure database. The investigator calls the newly diagnosed person and gathers information, including a list of every person the patient came in close contact with starting from 48 hours before their symptoms emerged.

“That’s because people can be infectious before they get symptoms,’’ Wroe said.

The case investigator gets the names and phone numbers of those contacts, which officials expect to be about 10 people per new case. Those are passed on to one of the contact tracers, who will attempt to reach each one by phone, ideally within 48 hours, and urge them to self-quarantine.

An early challenge that has emerged: Getting people to pick up the phone, said John Welch, a senior nurse anesthetist at Boston Children’s Hospital, on loan to PIH for the contact tracing program. The collaborative has been working with telecom companies to make that more likely. Now when a tracer calls, it should pop up on caller ID as “MA COVID Team,’’ and have a number with the prefix 833 or 857.

Speaking from a script, the tracer informs each of those contacts that they have been exposed to the virus, and then walks them through how they can safely isolate at home for a 14-day period.

The conversations include checking if people are showing symptoms or need testing, as well as seeing if they have what they need to quarantine safely. If they don’t, the program has resource coordinators who can connect the person to social services such as food banks or mental health services. The contact tracers continue to check in with people during their quarantine.

While it’s labor intensive, officials involved in the Massachusetts program say the human element is critical.

You can’t get people to isolate through “force and fear,’’ said Welch, who oversees the brigade of contact tracers. He previously served as the chief clinical officer for PIH’s Ebola response in Liberia and Sierra Leone during the outbreak that began in 2014. “You have to do it with empathy.’’

“The human part is kind of like the glue,’’ said Wroe. “There’s the very real human connection of, ‘I see you. . . . This is scary and we are here for you, even though we’re on the phone.’ ’’

Some critics have suggested it’s too late for contact tracing to curb the spread of the coronavirus. State officials and the PIH staff vehemently disagree. Contact tracing can reduce the spread of the disease beyond even what social distancing can do, not just flattening the curve, but bending it downward, they say. That only happens when each infected person spreads the disease to fewer than one other person.

Moreover, putting a robust program in place will allow the state to quickly respond to flare-ups in the future, without needing to lock down the whole economy again.

“That’s what contact tracing is for — to help us have a long-term solution so that our lives can go back to a new normal,’’ said Wroe.

“We’re on top of the mountain right now with COVID,’’ said Welch. He recalled feeling daunted by the Ebola infection totals that would come in each day from around West Africa, wondering, how will this ever end? But he also was there when they tracked down the last few exposed households through contact tracing, an effort that involved thousands of community health workers traveling on foot. He said he wept the day the epidemic was finally declared over.

“If you don’t have a vision that it will end, then you’re doing nothing, you’re just sitting around,’’ said Welch. Contact tracing, he said, is a key part of getting down the mountain, especially before effective treatments and a vaccine are widely available. Those take time.

“In the meantime, we can’t do nothing. We have to do these things that we know work,’’ he said. “It is a way out.’’

Victoria McGrane can be reached at victoria.mcgrane @globe.com.