He urged residents to continue following safety protocols such as hand washing, face coverings and physical distancing and cautioned against large gatherings.

“We are all vulnerable to this virus,” he said. “Now is not the time to let our guard down.”

He also noted that the island is entering a more concerning time as the summer winds down. During the fall and winter months, he said, “as we huddle indoors and come closer together the risk for transmission increases.”

Santamaria stressed that respecting the virus is potentially a matter of life and death.

“These precautions will help prevent that transmission,” he said. “Please do your part, because the life you are saving may be in your own family. … Thank you, and be safe.”

As of Monday, Nantucket Cottage Hospital, the island’s lone hospital, had logged 52 positive coronavirus tests out of just over 6,000 since mid-March, according to the hospital’s website. The island currently has about nine active COVID-19 cases, Santamaria said Tuesday by phone.

And Nantucket remains in the lowest risk pool in Massachusetts for COVID-19 transmission, according to the most recent weekly public health report the state DPH released Wednesday.

But the island, a popular summer tourist hub, has had prior issues with gatherings this season amid the pandemic.

In response, town officials last month voted during a joint meeting of the Nantucket Board of Health and Board of Selectmen to mandate that bars and restaurants close at midnight, with an 11:30 p.m. last call for alcohol. The order did not apply to restaurants that don’t serve adult beverages.

Santamaria had said during the joint meeting that many island visitors had been seen leaving restaurants inebriated after closing, often without masks or not observing social distancing.

“It’s mostly at night that we’re seeing the problems,” Santamaria said, adding that some restaurants had voluntarily started closing early.

And Stephen J. Visco, chairman of the Nantucket Board of Health, said during that same July meeting that the early-closing order could help protect public safety.

“I believe that it’s going to help,” he said, “Any way we can help is fine with me.”

Travis Andersen can be reached at travis.andersen@globe.com. Follow him on Twitter @TAGlobe.