On the first hot weekend of the summer, Richard Knapp put up a sign outside Mother’s Ruin, a bar tucked in Manhattan’s SoHo neighborhood. It had two arrows: one pointing vaccinated people indoors, another pointing unvaccinated people outdoors.The Instagram post showing the sign (above) quickly went viral among European anti-vaxxers on Reddit. “We started receiving hate mail through the Google portal,” Knapp says, estimating he’d received about a “few dozen” emails: “I’ve been called a Nazi and a communist in the same sentence. People hope that our bar burns down. It’s a name and shame campaign.” It wasn’t just the...