Perhaps this is a condemnation of how poor indoor air quality is in most schools (and office spaces) more than anything. While there are plenty of studies show

Perhaps this is a condemnation of how poor indoor air quality is in most schools (and office spaces) more than anything. While there are plenty of studies showing efficacy of masks in indoor environments, we're barely recirculating air in indoor spaces to the point where CO2 levels become a major problem for cognition. The combination of proper ventilation and air exchange plus masks should be the real winner for prevention of spread.