For many US schools welcoming students back, a return to in-person learning was abruptly halted after new Covid-19 cases. More than 2,000 students, teachers and staff members across five states have been quarantined after at least 230 positive coronavirus cases were reported. It's a grim start to the school year many hoped could mark the beginning of a return to normalcy, but one experts have long warned would come at a cost. More studies have shown how easily children can get and spread coronavirus. But some pediatricians caution that distance-learning has negative consequences for primary-age students and for working families. The dilemma has forced school districts to navigate whether to re-open, and what to do if in-person learning proves dangerous.