THE MASSACHUSETTS contact tracing collaborative is laying off 10 percent of its workforce this weekend as COVID-19 case counts continue a steady decline that prompted Gov. Charlie Baker on Thursday to set March 22 as the starting date for the fourth and final phase of the state’s reopening plan.

State officials said 170 of the collaborative’s 1,747 employees will not be granted employment extensions beyond this weekend. More reductions are likely if case counts continue to fall and as more and more of the population is vaccinated.

Working under a contract with the state of Massachusetts, the collaborative, which is run by the nonprofit Partners in Health, contacts those infected with the coronavirus and tracks down all those who they have come in close contact with (within 6 feet for at least 15 minutes) to urge them to get tested and quarantine. The program also employs resource coordinators to help those who need food, health care, or other services in order to shelter and recover or quarantine.

Staffing levels at the collaborative work a lot like an accordion, expanding when the disease is spreading and contracting when it is in decline. The collaborative hit a peak staffing level of 1,900 during the first surge, fell to as low as 470 in July and then expanded during the most recent surge to its current level.

Jason Lefferts, a state spokesman, said current staffers are capable of managing 2,000-2,400 cases a day, but the seven-day average is 1,200-1,500 cases a day. With fewer employees after this weekend, Lefferts said the collaborative’s workforce will be capable of handling 1,400 to 1,700 cases per day.

On Friday, the state’s COVID-19 dashboard reported 1,734 new cases and 46 deaths.