Morse High School and the Bath Regional Career and Technical Center will reopen for part-time in-person learning after closing Monday through Wednesday due to a COVID-19 outbreak in the schools.

In a letter sent to families Wednesday, Regional School Unit 1 Superintendent Patrick Manuel said one additional COVID-19 case was reported during the three-day closure, adding to a wave of recent cases in the schools. However, Manuel credited the cases to community transmission rather than in-school transmission.

Upon reviewing recent COVID cases with the Maine CDC, the school physician and the school nurse, “… we are confident at this point that all cases were a result of community spread and that no in-school transmission or transmission during athletic programming has taken place,” Manuel wrote.

According to Maine CDC Spokesperson Robert Long, outbreak and case investigators are able to decipher community spread from in-school transmission by “exploring potential lines of virus transmission.”

“Those investigations can confirm potential transmission routes,” Long wrote in a statement Wednesday. “They can also help rule out potential transmission routes.”

Three “individuals associated with” the schools tested positive for COVID-19 over the weekend, leading the schools to move to total distance learning, according to another letter that Manuel sent Sunday.

While the schools were “certain there is no in-school transmission as none of the cases are connected from in-school circumstances,” it closed to monitor potential cases to “ensure we do not have in-school transmission,” Manuel wrote to families Sunday.

The closure came after three individuals associated with the schools tested positive for COVID-19 last week, leading the Maine Center for Disease Control and Prevention to declare a COVID-19 outbreak at Morse High School and Bath Regional Career and Technical Center, which share a building.

An outbreak is defined as three or more cases of COVID-19 within a 14-day period, according to the Maine CDC. The school will shed its outbreak status if no new cases are reported in 14 days.

“It is more important than ever to follow all safety protocols whether in school or not, especially mask wearing, social distancing, and hand washing,” Manuel wrote. “All new cases impact the chances for in-person classes, a full spring sports season, and celebrating graduation events in-person.”

In total, RSU 1, which includes Bath, Arrowsic, Woolwich and Phippsburg, has seen 32 confirmed COVID-19 cases since school restarted, according to the district website.

High school students will return to in-person instruction as the state experiences a rise in COVID-19 cases, driven largely by younger Mainers.

Wednesday was the second consecutive day the Maine CDC reported more than 500 new cases in a single day. Of the 547 new cases, 247 (45%) were people under 30, the Portland Press Herald reported. Another 136 (25%) cases were people in their 30s.

The day before, 297 of the day’s 571 new cases were people in their 30s and another 140 were people in their 30s.

In Sagadahoc County, 1,126 people have tested positive for COVID-19 since March 2020 and eight have died, according to the Maine CDC.

Since the pandemic began, there have been 55,374 confirmed or probable cases statewide and 757 people have died as of Wednesday.