AUBURN — In a letter to the school community sent Thursday afternoon, Superintendent Cornelia Brown wrote that masks will now be required in all school buildings.

The decision follows a notification from the Maine Center for Disease Control on Thursday that Edward Little High School is experiencing an outbreak of COVID-19. An outbreak is defined as three or more epidemiologically linked, confirmed cases of COVID-19 from different households during a 14-day period.

In the past 14 days, five ELHS students have tested positive.

Previously, masks were optional at the middle and high schools, but required in all elementary schools. Students and staff at Auburn Middle School, Franklin Alternative School, Regional Education Treatment Center and ELHS will begin practicing universal masking Friday.

“Out of an abundance of caution, we are taking another mitigating step,” Brown wrote in a statement to the Sun Journal.

According to the Auburn School Department’s guide to opening schools, the superintendent has the authority to “make changes regarding masking, remote learning, and school closure, in response to COVID-19 cases and specific needs at each school.”

Library assistant Karen Landry works Thursday from behind a mask and protective plexiglass at the Edward Little High School library in Auburn. Daryn Slover/Sun Journal

The letter does not specify under which conditions the district might return to optional masking in the middle and high schools.

ELHS Principal Scott Annear said he expects students and staff to quickly adapt to the new mask requirement.

“It’s not new territory. We’ve done it before,” he said, adding that he is confident students and staff will do whatever they have to do to stay in school.

Due to vaccines, the number of students and staff who have to quarantine in response to positive cases has halved, Annear said. According to district policy, fully vaccinated students and staff do not have to quarantine, even if they are a close contact, unless they present symptoms.

The most challenging aspect of the outbreak has been keeping students who are unable to attend school in person up to speed with coursework, he said. As of Thursday, 28 ELHS students are in school-directed quarantine.

The uptick of cases in the Auburn School District began Oct. 13, when six students were reported positive for COVID-19. Since then, an additional 19 students have tested positive.

As of Thursday, 62 students and seven staff members have tested positive for COVID-19 since the school year began Sept. 1, resulting in 523 close contacts and 310 school-directed quarantines.

Fairview Elementary School has recorded 15 cases of COVID-19, the most of any school in the district. AMS has the second highest total with 12 cases.

Fairview and Sherwood Heights Elementary School, which has recorded six cases, were both designated as outbreak status by the Maine CDC earlier this month.

According to the Maine Department of Education dashboard, an outbreak investigation will close when there has not been a new case associated with the school for 14 days.

The rise in cases in schools reflects an increase in cases in the larger community. From Sept. 19 to Oct. 17, the Maine CDC reported 193 new cases of COVID-19 in Auburn. Thirty-six of those cases alone were from the week ending Sunday.

Neighboring Lewiston has recorded even more cases in the past month, 270 as of Oct. 17.

Maine CDC Director Dr. Nirav Shah said in early September that last school year, there was little evidence that transmission of the virus was occurring within school settings. It was more likely that school outbreaks were driven by community spread of the virus, rather than the other way around.

In her letter, Brown also wrote that the school district is exploring the possibility of collaborating with local health care providers to offer COVID-19 vaccines to students ages 5-11 after the federal Food and Drug Administration authorizes its use for children.

Additionally, all students and staff in the district are eligible to sign up for the school’s pooled COVID-19 testing program, which is scheduled to begin in November.