Schools across the United States over the weekend announced last-minute closures due to the spread of COVID-19. Students in a number of districts are slated to return to class on Monday morning from the winter break. Some districts blamed the closures on staffing issues or the rise in cases driven by the Omicron variant. In Massachusetts, more than a dozen separate school districts were closed or delayed opening on Monday, Jan. 3, with officials citing the spread of COVID-19 and some snowfall. Also on Monday, in another example, the Pittsburgh Public Schools announced it is shuttering 12 schools due to staffing shortages caused by COVID-19, WXPI reported. A local infectious disease expert who was interviewed by the local station said that it’s “inevitable that we’re going to see cases in the school” but stipulated closures “can’t be tolerated.” “We have rapid tests, we’ve got antivirals, we have vaccines, we have monoclonal …