MINNEAPOLIS (AP) — The head of one of the largest regional health systems in the Midwest has told his employees that he has recovered from COVID-19 and is back in the office — without a mask.

Sanford Health’s president and chief executive, Kelby Krabbenhoft, said in an email Wednesday that he believes he’s now immune to the disease for “at least seven months and perhaps years to come” and that he isn’t a threat to transmit it to anyone, so wearing a mask would be merely for show.

The email from Krabbenhoft, who is not a physician, comes as hospitals throughout the region, including in his own network, are struggling to keep up with some of the country’s worst surges of coronavirus patients. And it comes at a time when mask wearing remains a politicized issue in many states.

Sanford Health, based in Sioux Falls, South Dakota, has 46 hospitals and more than 200 clinics concentrated in South Dakota, North Dakota, Minnesota and Iowa. It employs nearly 48,000 people. The Dakotas have had the country’s worst spread rates for several weeks, with Iowa close behind, while Minnesota is catching up.

“For me to wear a mask defies the efficacy and purpose of a mask and sends an untruthful message that I am susceptible to infection or could transmit it,” Krabbenhoft wrote in the email, obtained by The Associated Press. “I have no interest in using masks as a symbolic gesture. … My team and I have a duty to express the truth and facts and reality and not feed the opposite.”

South Dakota Gov. Kristi Noem has refused to impose a statewide mask mandate. North Dakota Gov. Doug Burgum did so last week after months of pressure. Other Republican governors, including Iowa’s Kim Reynolds, have started to shift on mask mandates as their hospitals fill. Minnesota’s Democratic governor, Tim Walz, ordered one back in July.

Krabbenhoft did not immediately respond to a Friday interview request. Sanford Health posted a statement on social media that didn’t directly address his comments but said: “From the start of the pandemic, our health care providers have called upon our communities to do their part by wearing masks and physically distancing to slow the spread of the virus. This is the best way to reduce stress on our health care system.”

Sanford Health requires clinic employees and hospital and clinic visitors to wear masks, according to its website. It wasn’t immediately clear if Krabbenhoft’s decision to not wear a mask opens the door for anyone else who works at or visits a Sanford facility to opt out of wearing one if they say they’ve already had the disease.

The CEO did not explain in his email why he thinks he’s immune for at least seven months.