Contact tracing isn't new. It helped during the Ebola outbreak in West Africa, and now the method is helping Massachusetts track and isolate the spread of the novel coronavirus.

While some Asian countries have managed to trace the spread of COVID-19 through digital tools, Massachusetts is relying on a drove of people to identify cases through outreach via telephone interviews of diagnosed patients and their close contacts.

Paul Farmer, co-founder of the nonprofit Partners in Health which is coordinating the program, told Boston Public Radio on Thursday though the method may be tried and true, there are still variables due to the novel nature of COVID-19.

"The mystery part is, how long does the contact need to be," to be considered a close contact, and therefore trigger outreach from a contact tracer, he said.

Farmer said Massachusetts' Community Tracing Collaborative effort takes "a lot of support" to be able to properly isolate contacts found through the program, but it's a necessary tool.

"The best thing you can do is have a very conservative idea of how readily the pathogen can be transmitted," he said. "It's great to have more people than you need on your contact list, that means you're doing a good job."

Dr. Paul Farmer, physician and anthropologist, is chief strategist and co-founder of Partners In Health. During his segment, he also took calls from listeners about contact tracing.