The state-run COVID-19 Community Tracing Collaborative (CTC) is increasing its staff, almost tripling in size as the delta variant spreads.

Its “frontline workforce” has increased from a total of 170 full-time employees in July to 480 now, according to a collaborative press officer. The program, run through a contract with Boston-based nonprofit Partners in Health in conjunction with the Department of Public Health, will eventually have 500 contact tracers, 100 COVID-19 case investigators and 75 COVID care resource coordinators working remotely, according to a job listing posted this week.

At its peak, roughly 2,200 full-time employees worked on the CTC team in January 2021. That staff extended beyond contact tracers, also encompassing case investigators, care resource coordinators, the epidemiological intelligence unit, local health liaisons, higher education liaisons and specialty teams like data and management.

Contact tracers reach out to people diagnosed with the virus, collect information about the people they’ve come in contact with and then proceed to call those people in an effort to get them tested or quarantined.

“Since April 2020, the CTC has adjusted staffing to meet the number of COVID-19 cases and needs of local health departments,” the group said in an emailed statement. “The CTC’s contract with the Commonwealth will be extended through the end of the calendar year and will make staffing adjustments accordingly in response to demand.”

Gov. Charlie Baker announced a $44 million contact-tracing program in April 2020. By mid-May of that year, the state had hired more than 1,000 people to be a part of the contact tracing collaborative, not including roughly 100 employees borrowed from Blue Cross, Blue Shield of Massachusetts. Employee numbers have fluctuated, with layoffs in the hundreds reported in June 2020 as well as spring 2021.

Partners in Health said in the job posting for a tracing supervisor that the “current COVID-19 pandemic exceeds the existing Massachusetts Department of Public Health and Local Boards of Health ability to perform contact tracing.” The organization said that, as a result, many people don’t know they have been in contact with a person who has COVID-19.

“To break the chain of transmission, contact tracing and isolation must be scaled-up rapidly,” said Partners in Health online. Partners in Health did not respond to requests for comment or interviews from GBH News.

Since last April, more than 600,000 cases and close contacts have been identified for outreach by the collaborative contact tracers, according to the state, and more than 80% of those cases and close contacts have had outreach completed. The collaborative’s press person said tracers have made 2.4 million phone calls to cases and contacts since opening in April 2020.