California will lift capacity and distancing requirements on June 15

Covid-19 case numbers in elementary schools appear to be 37% lower when teachers and staff are required to wear masks, and 39% when air ventilation is improved, according to new research published by the US Centers for Disease Control and Prevention.

The findings are based on data from before coronavirus vaccines became available, but until children younger than 12 are eligible for the vaccine, “universal and correct mask use is a…