Trump’s supporters in Pennsylvania echo his misinformation on the virus.

ANNVILLE, Pa. — Entering Ted’s Bar and Grill on Monday, Tim Girvin briefly slid on a “Trump 2020" face mask before whisking it off to join friends for lunch.

He said those few seconds were the only time he wore a mask all day.

“I have my own business and I don’t have anybody wear a mask in my business,” Mr. Girvin, a used-car dealer, said. “I don’t buy into it.”

On the day that President Trump left the hospital and returned to a White House that is Washington’s most contagious hot spot, ripping off his own mask for the cameras, backers of the president in rural Pennsylvania showed signs of following his lead in questioning, and defying, advice from public health experts.

Mr. Trump’s failure to protect his family and inner circle from the virus was not seen as a reflection of his inability to protect Americans, as the death toll passed 210,000, the most of any country.