Masking Adherence in K-12 Schools and SARS-CoV-2 Secondary Transmission.

Objectives: Masking is an essential coronavirus 2019 mitigation tool assisting in the safe return of kindergarten through 12th grade children and staff to in-person instruction; however, masking adherence, compliance evaluation methods, and potential consequences of surveillance are currently unknown. We describe 2 school districts' approaches to promote in-school masking and the consequent impact on severe acute respiratory syndrome coronavirus 2 secondary transmission.

Methods: Two North Carolina school districts developed surveillance programs with daily versus weekly interventions to monitor in-school masking adherence. Safety teams recorded the proportion of students and staff appropriately wearing masks and provided real-time education after observation of improper masking. Primary infections, within-school transmission, and county-level severe acute respiratory syndrome coronavirus 2 infection rates were assessed.

Results: Proper mask use was high in both intervention groups and districts. There were variations by grade level, with lower rates in elementary schools, and proper adherence being higher in the weekly surveillance group. Rates of secondary transmission were low in both districts with surveillance programs, regardless of intervention frequency.

Conclusions: Masking surveillance interventions are effective at ensuring appropriate masking at all school levels. Creating a culture of safety within schools led by local leadership is important and a feasible opportunity for school districts with return to in-person school. In our study of schools with high masking adherence, secondary transmission was low.