LEWISTON — A student at Lewiston Middle School has tested positive for COVID-19, the district announced Friday in a letter to the community.

The student was last in school the morning of Sept. 18, according to Assistant Superintendent Karen Paquette.

She wrote that 15 students and three staffers are in quarantine. They are members of a seventh-grade team that attends school Thursday and Friday.

The infected student rode a school bus Friday, Paquette said in an interview.

“We have confirmed that all of the students were wearing masks and followed social distancing guidelines,” she said.

She said several windows were open and the student was on the bus less than 15 minutes. Other students on that bus will be contacted, but they will not be required to quarantine.

Those in quarantine will be contacted directly by Center for Disease Control and Prevention contact tracers and school personnel, according to the community letter.

The other students and staff on that seventh-grade team, groups A (Monday and Tuesday) and B (Thursday and Friday), will work remotely “out of an abundance of caution” through Friday, Oct. 2, Paquette wrote.

“We have taken steps with our response team to follow Maine Center for Disease Control and Maine Department of Education guidelines to notify staff,” Paquette wrote.

If neither school staff nor the CDC has contacted you, there will be no disruption to your school “at this time,” she said.

According to state guidelines, a school would be closed if it reached outbreak status, which is three cases within 14 days, she said.

The district announced Monday that a student at McMahon Elementary School has tested positive for the airborne virus. This student did not ride the bus.

Also, a staffer at Connors Elementary School in Lewiston was in quarantine last week pending a COVID-19 test. The staff person had been in close contact with a family member who tested positive.

For general questions about COVID-19, call 1-866-811-5695, text your ZIP code to 898-211 or email info@211maine.org.

Information also is available at www.maine/gov/dhhs/coronavirus or www.cdc.gov/coronavirus.

Questions can be directed to the superintendent’s office by calling 795-4100 or by contacting the nurse at your child’s school.