TOPEKA — The health department in Kansas’ most populous county urged its public schools Monday to require students and staff who aren’t vaccinated against COVID-19 to wear masks indoors when classes resume for the fall.

The Johnson County Department of Health and Environment’s guidance came with confirmed cases of the faster-spreading delta variant continuing to rise across Kansas and fueling larger numbers of new COVID-19 cases overall.

“We want a return to normalcy, but we need to be cautious and get vaccinated if eligible.” said Dr. Sanmi Areola, the department’s director.

Lance Williamson, a registered nurse and infection prevention consultant for the University of Kansas Health System, said wearing masks is a “basic precaution” against COVID-19.

“Especially when you’re unsure of the unvaccinated people versus vaccinated people in an area, it’s just easier to have everyone wear a mask,” he said during a daily health system webcast.

The state reported Monday that confirmed delta variant cases increased by 20% since Friday, up 158 to 950. Confirming variant cases requires genetic testing of patients’ nasal swabs or saliva samples.

State data also showed that Kansas averaged 440 new COVID-19 cases overall for the seven days ending Monday, the highest such average since Feb. 26.