A student at a private middle school on Oahu contracted COVID-19, prompting a Health Department investigation and contact tracing of more than 100 people — but only one other student ultimately tested positive.

The investigation was included in the department’s weekly COVID-19 Cluster Report issued today, which focused this time on transmission in educational settings, from college dorm parties to classrooms.

“The high number of potentially exposed individuals was due to the fact that the index case, a middle school student, moved to different classrooms throughout the day in order to participate in classes for nine different subjects,” the Department of Health wrote in its report.

“All exposed individuals quarantined for the full 14 days and approximately 90% were tested for COVID-19,” the report said. “Only one additional case was identified; a student sitting directly in front of the index case for a full class period the day that the index case became symptomatic.”

The report also highlighted coronavirus clusters in Hawaii among college students attending parties in dormitories. One Halloween party at a dorm on Oahu attracted students from several universities and wound up with five individuals infected, according to the report.

A third case of transmission in a school setting took place at an elementary school. Four employees, who were cafeteria workers and custodians, regularly ate lunch together and all tested positive, according to the Health Department. No students or other staff members were exposed.

The cluster report does not identify any of the schools.

“We won’t do that unless there is an imminent health risk,” Health Department spokesman Brooks Baehr said. Asked if the individuals had fully recovered, he said the department does not disclose personal medical information.

Deputy state epidemiologist Sarah Kemble said the report is designed to share lessons and help stop the spread of coronavirus, not “to call out a specific setting.”

“The purpose of the report is really to describe the situation rather than the specific institution,” Kemble said. “It’s to understand what types of settings we might see transmission in and why… What other measures could be in place to minimize that transmission — that’s what we hope to learn from analyzing the clusters.”

Most public schools are still in distance learning and the Department of Education confirmed that the middle school was not a public school.

The Health Department said that universal masking policies were in place throughout the campus, but some classrooms lacked sufficient space for 6-foot distancing among student desks.

Kemble said the case was “reassuring in some ways” in that it did not spread further, given that the student “had been in nine different classes rotating throughout the day, which could be a scary situation.”

Schools have been advised to keep students in small cohorts to minimize the potential for spread if someone contracts the virus.

“All of the clusters described here are still under investigation,” Kemble said. “The story may not necessarily be complete. These are the kinds of transmission factors that have been identified. That dorm party setting is risky.”

She said the department is advising caution during the coming holiday season.

“This is a really critical time for us to think about how we share those special holidays with our families,” she said. “It’s so important to have both yourself and your community stay healthy when you celebrate.”

“Keep it small — five members or less,” she said. “Use Zoom to connect. You can each be enjoying food but not in the same space. Or take it outside.”