This week, the CDC issued revised guidance for schools on safe, in-person operation. The main change is a reduction in the physical distancing recommendations from at least 6 feet of space between students in classrooms to at least 3 feet, though there are also recommendations for when maintaining a minimum distance of 6 feet is still recommended. Notably, the American Academy of Pediatrics recommends that schools implement 3 to 6 feet of physical distancing and the World Health Organization suggests 1 meter, or 3.3 feet, between students in schools.

In addition to the distancing recommendation, the updated CDC guidance removes recommendations for physical barriers and clarifies that ventilation is a component of suggested strategies to maintain clean and healthy facilities. The recommendations also clarify the role of information on community transmission in making schooling decisions and include guidance on interventions when clusters of cases occur in schools. The guidance emphasizes that layered prevention strategies, including physical distancing and universal and correct use of masks, and an approach that accounts for community transmission can facilitate a return to safe, in-person schooling.

This topic has gotten a lot of attention because of a recent study, now forthcoming in Clinical Infectious Diseases. The researchers compare case rates in Massachusetts school districts providing in-person schooling with a 6-foot distancing requirement to those using a 3-foot distancing guideline. The case rates are based on student and school staff cases reported to the state. They find no (statistically detectable) differences in case rates based on the distancing rule and conclude that a guideline imposing 3 feet between students is sufficient for safe in-person schooling.

While no other work has directly compared school distancing policies to case rates, it is difficult to isolate the effects of the distancing rule itself when schools and school districts are employing layered prevention strategies. This study is limited in its ability to account for other factors that may differ across school districts that used the 3-foot rule and those that required 6 feet, including other mitigation strategies. It is also important to note, when considering the portability of their finding, that they tested this question with Massachusetts data where there was universal masking in schools and high compliance in communities. A June 2020 systematic review of the evidence on non-pharmaceutical interventions in mostly health care, and some community-based, settings found that masking was very protective and distancing of 1 meter lowered transmission of various viruses relative to closer distances, but that protection was enhanced with greater distance.