A new report from the CDC found that Covid-19 cases among younger children remained low even after schools restarted for in-person learning. To safely reopen schools, however, transmission in communities must be kept in check. … considered more than 2.8 million laboratory-confirmed Covid-19 cases in people ages zero to 24 from March 1 through December 12. More than 57% of those cases occurred among people ages 18 to 24. Cases among children and teens paralleled cases among adults through the summer and fall -- including spikes in cases in early summer followed by a decline, and then a steep increase in October through December.