Contact tracers who worked with the Boston-based nonprofit Partners in Health are being asked to come back in to work as new COVID-19 cases rise.

The program, which was scheduled to shut down next month, is now being extended until the end of the year. The nonprofit works with local boards of health across the state to track down people exposed to COVID-19.

Partners in Health currently employs 130 contact tracers and plans to add as many as 300 more.

Partners in Health did not immediately respond to a request for comment, but in a re-hire email obtained by GBH News, the nonprofit asked contact tracers to return, in order to “support local health departments as they scale up contact tracing back to municipalities.”

Rising case numbers, fueled by the new delta variant, were cited as the reason.