The U.S. nursing home industry’s resistance to forcing workers to get vaccinated against COVID-19 for fear that too many of them might quit began to crack this week when its biggest player announced its employees must get the shot to keep their jobs. The new requirement at Genesis Healthcare, which has 70,000 employees at nearly 400 nursing homes and senior communities, is the clearest sign yet that owners may be willing to risk an exodus at already dangerously understaffed facilities to quickly vaccinate the 40% of workers still resisting shots and fend off the surging delta variant.