Alabama public schools reported more than 26,000 cases of COVID-19 this week, and the outbreaks have prompted some of the state’s largest systems to make a temporary switch to remote learning.

The Alabama Department of Health dashboard on Thursday showed 26,260 virus cases reported this week in public schools. That compares to 16,035 the previous week. The Jefferson, Shelby, Mobile and Tuscaloosa County school systems each reported more than 1,000 cases.

In announcing the switch to remote learning, administrators in two large systems cited the difficulty in staffing schools because of the large number of teachers and staff members who are out sick.

Shelby County schools on Thursday announced a switch to remote learning beginning Friday and lasting through Tuesday. System administrators wrote that the switch was, “due to the high number of faculty, students, and staff who have tested positive for COVID-19 and the inability to staff schools effectively.”

Madison County schools announced Wednesday that students would be doing remote learning through Jan. 28 after a high number of COVID cases.

“The staffing shortage, including substitutes, is hampering our ability to operate schools safely and effectively,” administrators said in an announcement.

Mobile and Montgomery County schools had already switched to virtual instruction this week with plans to resume in-person class on Monday.

Several other schools systems announced students would be at home on Friday because of the threat of winter weather.