AZ Cardinals Owner Michael Bidwill

Good news for Arizona Cardinals owner Michael Bidwill ... who was released from the hospital Sunday after battling COVID-19.

The 55-year-old NFL owner tested positive last week after traveling to the East Coast and was admitted to Newport Hospital in Rhode Island. He had complained of headache and fever.

But now, he's on the mend -- and praising the medical workers who treated him.

"This week I learned first-hand just how serious COVID-19 is," Bidwill said.

"My immense appreciation for all those on the front lines of this pandemic has only increased and I am particularly grateful to the tremendous nurses and doctors at Newport Hospital."

"I am also overwhelmed by the outpouring of kindness from…