Northside Independent School District students, staff and visitors must return to wearing masks indoors Thursday as the district tries to combat the highly contagious omicron variant.

Superintendent Brian Woods said in a video posted to the NISD Twitter account Wednesday that the district will reinstate its mask mandate temporarily, “given the transmissibility of this strain of the virus and the student and staff absenteeism associated with it.” Almost 20% of students and 15% of staff missed school last week.

“The mandate is driven by concerns for student and staff safety and is not motivated by the current legal battles on this issue,” Woods said. “Masks have been used in health care settings for decades and have been shown to reduce viral transmission.”

San Antonio’s largest school district lifted its mask mandate Oct. 8 after COVID-19 cases driven by the delta variant peaked. More than 100,000 students attend NISD.

Texas school districts have been locked in a legal battle with Gov. Greg Abbott for months after he issued an executive order in July prohibiting school districts and other governmental entities from mandating masks. Dozens of school districts, including NISD, have sued the governor, claiming he lacks the authority to prevent districts from adopting mask mandates.

Some local districts — including San Antonio, South San Antonio, and Edgewood ISDs — have implemented mask mandates while the lawsuits wind their way through the Texas court system.

As of Tuesday, Bexar County’s positivity rate reached 38.3%, according to San Antonio’s Metropolitan Health District. The county recorded 5,413 new cases and a seven-day rolling average of 6,140.

Meanwhile, North East ISD is limiting its coronavirus testing to one site, the North East Sports Park, because shipping delays mean the district doesn’t have enough tests to administer. No testing will be done at schools until more tests arrive.

SAISD, which conducts weekly testing of students and staff members who want it, is pausing its on-campus testing while its testing partner, Community Labs, clears a backlog of unprocessed tests.

Brooke Crum covered education for the San Antonio Report.