All students and faculty members at Parley’s Park Elementary School are required to wear masks after the school passed a threshold for COVID-19 cases over the weekend.

A Summit County public health order mandates masks in elementary, middle and junior high schools if more than 2% of a school’s population is diagnosed with COVID-19 over a two-week span.

This is the first time a mandate has been implemented since the order was issued at the start of the school year. Officials have said the order is designed to stop an outbreak before it takes hold in a school.

On Sunday, the number of official cases passed the threshold, according to the Park City School District, and all Parley’s Park students, staff and visitors were required to wear masks starting Monday morning.

The mandate will be in place until Nov. 14, when the number of cases will be reevaluated. If fewer than 2% of the school’s population is diagnosed with COVID-19 in that two-week span, the requirement will be lifted.

Parley’s Park has a population of 594 people, which means that 12 cases surpasses the 2% threshold.

As of Monday, the school’s total had fallen to 11 cases. The school with the next highest percentage of its population diagnosed with COVID-19 was McPolin Elementary School, at just under 1%.

The state requires a “test to stay” program if any school the size of Summit County’s schools has 30 active cases over a two-week period. Officials have said one motivation for the mask order is to avoid having to implement the testing program, which they indicated is burdensome.

Park City Superintendent Jill Gildea asked parents to continue to keep children home if they are sick.

“COVID is still with us, and we’re seeing an uptick in cases of students and school-aged families,” she said.

The threshold initially appeared to be met last Thursday, according to data published by the district, but that was later reversed.

Officials indicated the data published last week included cases that did not fit the county’s definition for a confirmed case of COVID-19. The county requires a lab-confirmed test result and for the infected person to have attended school within 48 hours of testing positive.

The false alarm last Thursday prompted community members to question why the numbers were changed. A website that automatically publishes health metrics daily at 6 p.m. showed three new cases at Parley’s Park that day, bringing the total to 13 over a two-week stretch. When the numbers were later changed, the same number of new cases was reported, but the total had fallen to 11.

Health Director Phil Bondurant said at a Board of Health meeting Monday that officials examined the data when the threshold was hit to ensure it was properly calculated. He said school metrics, which are uploaded directly to the database by officials at individual schools, can include informal diagnoses.

“On the school district side, they had a different mechanism for determining cases. They were identifying cases that were called in from parents, saying that ‘We had a positive test,’ or ‘My kid was exposed and now is sick,’” Bondurant said. “And by case definition for the legal component of the order, we cannot include those because that’s not the case definition of a positive from the (Centers for Disease Control and Prevention) and the Utah Department of Health.”

Gildea said the district would make changes to how it reports cases that are published in the public-facing data dashboard.

“We are appreciative of the careful monitoring and data review provided by (the Summit County Health Department) and UDOH,” Gildea said.