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Here’s how contact tracing works in battle against coronavirus

A testing site in East Boston.David L. Ryan/Globe Staff

Massachusetts officials want residents to cooperate with the state’s contact tracing program. Here’s what you need to know about contact tracing, what the state is doing, and why it’s important in the fight against the coronavirus pandemic:

What is contact tracing?

To stop an infectious disease outbreak you need to stop the disease from hopping from one person to another. To do that, you need to find people who are infected with the disease and you need to trace the people who have been in contact with them. In the case of the coronavirus, the goal is to get people who have been infected to isolate themselves and their close contacts to do the same. With nowhere to go, the virus will be stopped in its tracks.


Has it been used before?

Contact tracing has long been a tool used by public health officials. It’s the same tactic they have used worldwide for decades to try to stop other infectious diseases, including tuberculosis, HIV, sexually transmitted diseases, SARS, and Ebola. “The development of modern methodical tools for contact tracing goes back to the mid-1800s,” according to

What is Massachusetts’ contact tracing operation like?

The state is using a large virtual call center staffed with more than 1,600 tracers. If a resident tests positive for the coronavirus, a tracer will call them to connect that person with the resources and support necessary to isolate themselves, the state says. The tracer will also ask who the infected person has been in close contact with and may have been exposed. “Then with your collaboration, the COVID Community Team will identify and reach out via phone and text to anyone you’ve been in contact with to trace and contain the onward spread of the virus,” the state says on its website. “It is important to note that we will not release your name to anyone. Your information is strictly confidential and will be treated as the private medical record it is.”


Governor Charlie Baker Baker has said that he would welcome if the state’s program could also work with new smartphone-based contact tracing efforts, but the state has not announced such an effort yet.

How has it been going?

Since April 12, according to the state, the COVID-19 Community Tracing Collaborative has reached nearly 14,000 confirmed cases and established more than 7,500 of their contacts. But Baker has urged residents more than once to cooperate with the tracing effort. Officials say you’ll know for sure when a contact tracer is trying to reach you because the area code will be 833 or 857 and the caller ID will say “MA COVID Team.”

“Please, pick up the phone. If you see a call or text from MA COVID Team and area codes 833 or 857, please pick up. You can help reduce the spread and save lives by doing so,” said Marylou Sudders, the state’s secretary of Health and Human Services, at a Thursday media briefing.

Jaclyn Reiss of the Globe staff contributed to this report.

Martin Finucane can be reached at