The degree to which Covid-19 spreads in K-12 schools depends on a host of factors, according to epidemiologists and public-health officials. They include whether masking and other safety measures are in place as well as the rate of transmission in the surrounding community.

In guidance issued Friday, U.S. Centers for Disease Control and Prevention said K-12 schools should be last to close when governments impose restrictions and should be reopened ahead of nonessential businesses and activities.

source: wsj.com