Active coronavirus cases more than doubled locally, up from 91 to 185 in a week, according to Monday numbers posted on the town website.
A cluster of 44 cases is reported at an assisted living facility, said town Director of Health Thomas Carbone. He would not name the facility.
Most of the other cases are clusters within households, he said.
"We are working with the assisted living facility to make sure the residents are being cared for," Carbone said.
Outbreaks in assisted living facilities are tracked by the state via self-reported data. The most recent update of active cases at such facilities provided by the state Nov. 15 did not have any Andover facilities on the list.
The increase in numbers comes at the same time Andover health and school officials worry about people traveling for Thanksgiving.
"The message really hasn't changed. We want people to keep safe distances," Carbone said.
He and his siblings' families are likely going to have dessert with each other over Zoom, he said.
"Don't go from party to party," he advised. "Stay to a small group. If you are out and about wear a mask and use hand sanitizer."
Likewise, the school district is closely monitoring cases, Superintendent Sheldon Berman said.
The high school went fully remote Nov. 6 after 167 students were quarantined because they came with someone who had the virus, according to school Director of Communications Nicole Kieser. Students who were in the same class as someone who tested positive are routinely quarantined, she said.
Sixteen staff members were also quarantined before the school went remote Friday afternoon. Schools will remain remote at least through Nov. 30, she said.
"The decision (to move to remote) was made following consultation with district and high school administrators, the director of nursing and the town’s Health Division," Kieser said in an email. "Our goal is to protect students and staff to mitigate the threat of transmission. Additionally, we require a certain number of staff to provide in-person learning for our students, and the number of staff quarantines made it difficult to continue with in-person classes."
Because students move between multiple classes at the high school throughout the day more people are exposed when someone tests positive, Kieser said.
Although the recent cases and switch to remote came after Halloween weekend, "we have no information that links these cases to any social gathering," Kieser said.
Carbone, whose department assists with contact tracing, said he does not know if students were exposed at a social gathering, either.
"I'm not aware of that," he said when asked to address rumors of a party. "It wouldn't surprise me, but I'm not aware of that."
The town would "be in the red" if the state had not changed its metrics for determining risk last week, Carbone said.
"What's keeping us in the yellow is the percent of positive is less than 5%," he said.
However, Andover's positivity rate increased to 1.2% from 0.88% the week before, he said.
"Wear your mask. Wash your hands. Do not attend large gatherings with people outside your household," Carbone stressed. "It's not only about protecting yourself and your family, it's about protecting everyone and stopping the spread."