Meat packers across North America are bracing for a resurgence of coronavirus cases, trying to avoid the shutdowns that left supermarket shelves empty earlier in the pandemic. Cargill Inc. has temporarily idled one of its beef plants in Canada after some employees tested positive, and will keep the plant shut at least through next week. JBS, the world’s top meat producer, sent thousands of vulnerable U.S. workers home on paid leave, while Sanderson Farms Inc. said it’s now facing higher absenteeism at its plants than earlier in the pandemic.