A fourth Steamship Authority employee in almost as many days has tested positive for Covid-19, according to a press release from spokesman Sean Driscoll Monday.

The employee was stationed on the ferry Martha’s Vineyard and last worked on a shift that ran from noon on Tuesday, Dec. 29 to 10:15 a.m. on Dec. 30, the press release stated.

“The crew member subsequently felt ill and was tested for Covid-19; after receiving a positive test result, the employee notified the Authority on Monday, Jan. 4, 2021,” the release states. “The Authority has notified vessel employees who were in close contact with the affected employee. Those employees will not be allowed to return to work until after receiving a negative test result or being cleared to work by a medical professional.”

The employee is the second crew member stationed on the Martha’s Vineyard to test positive for the virus in recent days. On Dec. 30, the SSA was informed of a positive test among a crew member, and subsequently had to cancel two midday ferry crossings between Woods Hole and Vineyard Haven.

Two other boat line employees, including a Palmer avenue-based bus and parking employee and a Vineyard Haven terminal staffer, have also tested positive for the virus. The bus employee tested positive on Dec. 31, and the terminal employee tested positive on Dec. 30. Both had previously last worked customer-facing shifts on Dec. 24.

It was not immediately clear if any of the four positive tests were connected. But Mr. Driscoll wrote in the release that the most recent positive test would likely not have any impact on the boat line’s regularly scheduled routes.

A small grouping of positive tests among employees this summer led to canceled trips and schedule changes.

“No operational changes or interrupts are anticipated as a result of this incident,” the release states.

The SSA has had dozens of staffers test positive since the pandemic began. Employees are required to stay home from work if they show virus symptoms, and receive a medical screening before reporting for duties. The boat line also uses hospital-grade disinfectant to clean all ferry and terminal surfaces every night.

— Noah Asimow