Sanford Health CEO says he had Covid and doesn't need a mask. His staff are appalled.

(CNN) -- The CEO and President of South Dakota-based Sanford Health says he will not be wearing a mask because he has already had Covid-19. Hospital staff are appalled. In an email sent Wednesday, which CNN obtained from a nurse at a Sanford Health hospital, CEO and President Kelby Krabbenhoft addressed the health system's 50,000 employees, explaining his decision.