The new guidance addresses all of this. The biggest change is the adoption of three feet of distancing for students as sufficient when all other prevention strategies are in place, including universal masking, hand-washing and enhanced ventilation. The CDC also added some other good caveats: When community spread is high and cohorting not possible, the CDC urges that middle and high schoolers revert to six feet. It also emphasizes times when masks cannot be worn and therefore the six-foot rule is needed, such as during lunch. (One of the best strategies we’ve seen for managing lunchtime is to have only half the school use the lunchroom each day, while the other students eat in their classes. Teachers can put on a movie to reduce talking, which keeps emissions low. And, of course, open the windows!)

The CDC also provided important tweaks on its community spread metrics. Now, it says that higher community spread could lead to in-school transmission, “if layered prevention strategies are not in use.” In other words, if schools have good controls, they can be open regardless of community spread. That’s a big change, and one that matches the science.

The report also now includes a full section on ventilation, with the guidance in line with what we have been saying for months: Schools should be bringing in more outside air and upgrading their filters. The report also dropped the recommendation to use plexiglass barriers, which can actually impede airflow. Cleaning is still overemphasized, unfortunately.