WESTON — The entire school district will move to a hybrid model on Monday amid a rise in reported COVID-19 cases, Superintendent William McKersie announced Thursday.

“Due to rapid escalation of COVID-19 spread in our region, and the evidence of spread among students within at least one school, we are shifting the entire district into hybrid mode,” he wrote in a letter to families and staff.

“We are doing so based on public health and medical guidance, and tracking similar decisions by area districts.”

The news comes amid a flurry of other announcements on Thursday of positive cases and students quarantining throughout the district.

School officials announced Thursday that 21 high school athletes had to quarantine after coming in contact with a positive case at an away sporting event last weekend. A fifth-grade student and a bus driver also tested positive Thursday. Officials said they couldn’t release the bus number for privacy reasons, but all students who rode it in the past 48 hours have been identified and contacted.

The fifth-grade student has not been in school for at least a week, so officials said there no other students or staff were at risk of exposure. They also stressed that this case isn’t connected to the other fifth-grade cases reported recently, including the two cases on Wednesday that officials believe are the first incidents of the virus being transmitted while in school.

It was also announced an eighth-grader and ninth-grader have each tested positive. Neither student had been in the school for more than a week and so officials said other students and staff were not at risk of exposure.

“We are in the high-risk category for infection spread, with the rate only increasing,” McKersie said in the letter announcing the move to hybrid. “This requires us to take steps to reduce the density in our schools. Our intent is to maintain as much in-person education as possible, for as long as possible. An immediate move to a hybrid mode is our best option.”

Weston has an infection rate of 20.2 daily cases per 100,000 people over the past 14 days, according to state data on Thursday. Nearly all of Fairfield County is a red alert town under the state’s new classification system.

Under the model, the elementary and intermediate school will use its full-day hybrid schedule, with an early dismissal on Wednesdays. The middle school will use its existing hybrid schedule and the high school’s new hybrid schedule will still take effect on Monday. The early learning center will remain in-person.

“Each school will be sending out communications on their specific hybrid schedules,” McKersie said.

He cautioned the district might have to move to a “longer-term temporary remote mode,” but it’s only going remote temporarily now due to staffing shortages or contact tracing.

“However, a longer-term temporary remote mode may be required if COVID-19 spread makes it unwise to have any amount of in-person schooling,” he said. “Other districts in Connecticut have had to take this step already.”

Some of these districts include Danbury, Shelton, Ansonia and Seymour. Bridgeport announced Thursday it will go fully remote starting Nov. 23.

“Regardless of our schooling scenario, WPS professionals are dedicated to maximizing academic growth and social-emotional learning for all students,” McKersie said. “Whether in hybrid or temporary remote, we are working to ensure ample instructional time, while allowing for ‘screen-time breaks’ and other respites from a full school day of digitally-based learning. Each school will make these plans and approaches clear to students and families.”

He ended his letter like many of the district’s other coronavirus-related announcements calling for people to continue to follow the mitigation practices. These include wearing masks, standing far enough apart, staying home if they’re feeling ill, as well as following quarantine protocols and the governor’s travel guidelines.

“Working together, with optimism, good will and mutual support, we will surmount COVID-19,” McKersie said.

kkoerting@newstimes.com