As they walked in the hot spring sun this April and May, these four have another mission. They are using their powers of persuasion to get more neighbors to take the Covid-19 vaccine.”Excuse me,” Joyce Barlow says to Sherod Shingles, a young man who comes out his front door in shorts and a Utah Jazz shirt, a white medical mask on his face. “Have you had your Covid-19 vaccine?”The volunteers circle around him at a pandemic-safe distance. “Nah,” Shingles says.