Maine health officials have identified a new outbreak of COVID-19 at the Portsmouth Naval Shipyard in Kittery, where 18 workers have tested positive for the disease.

Thirteen of those cases have been among Maine residents, including seven who regularly commuted together to the shipyard in one van from the York County city of Sanford, according to Nirav Shah, director of the Maine Center for Disease Control and Prevention.

Four cases are among New Hampshire residents, and one was detected in a Massachusetts resident. Shah said that the “early initial hypothesis” is that those workers who commuted together from Sanford sparked at least some of the outbreak at the Kittery shipyard.

Sanford and the neighboring town of Alfred have been the site of numerous other outbreaks in recent weeks, including at the York County Jail, Calvary Baptist Church and a number of private social clubs in the city where cases could be linked to a late August funeral reception at an American Legion Hall.

“This is an example of where a high baseline number of cases in the York County area can — when folks get together — generate an outbreak, and in the case of a shipyard, potentially expose a very high number of workers,” Shah said.

He added, “I can definitely say that this is a reminder that keeping a lid on the number of COVID cases is important to prevent an outbreak like this one.”

Shah on Thursday also announced one other new virus outbreak in Sanford, at the Baker Co. manufacturing plant, which makes scientific equipment. Three people at the plant so far have tested positive for the coronavirus.

In addition, the state announced a new virus outbreak at the Buffalo Wild Wings restaurant in Auburn, where four workers have tested positive.

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