Barbara Sibley’s four New York restaurants had already weathered the city’s initial Covid-19 wave, the prevaccine surge last winter and this summer’s Delta spike when last weekend it finally happened: Fearing an outbreak and struggling with staffing after one of her workers got sick with Covid, she temporarily shut down one of her locations.That was only the start of Ms. Sibley’s worries. She also had to weigh how long the employee, who was fully vaccinated, should isolate before returning to the job. And the messaging from public health experts was not clear-cut.In the early days of the pandemic the Centers for Disease Control and Prevention recommended that most people who tested positive for the coronavirus isolate for 14 days. It later …
