ST. CLOUD — The Minnesota Correctional Facility in St. Cloud has the largest outbreak of coronavirus cases in the state’s prison system in months.

According to corrections officials, 242 inmates have tested positive for COVID-19. That’s nearly a quarter of the inmate population at the St. Cloud prison.

The state Department of Corrections is working with the Department of Health to determine why cases have spiked since protocols haven’t changed, WCCO-TV reported.

Officials say a number of factors may be in play; including growing rates of community spread, the need for booster shots as vaccines wane and a switch to the prison’s heating system instead of circulating fresh air.

New COVID-19 concerns come at a time the union that represents corrections officers has sounded the alarm over what they call dangerous staffing levels statewide. The pandemic had led to early retirement for some officers who don’t feel safe in a difficult setting for a highly-infectious disease, the union said.

“This is a department-wide problem, and this is a safety issue,” said Dan Gorman, a corrections officer at Stillwater and union president. “Some people chose to made that decision to leave a job they loved and they were committed to, some earlier than they wanted to.”

Gorman says in his 16 years at Stillwater prison, he’s never seen staff numbers so low.

“They’re required to work sometimes 16 hours back-to-back days to make sure we have the coverage needed and necessary to maintain the security levels of these institutions,” Gorman said.