Mask Interventions in K12 Schools Can Also Reduce Community Transmission in Fall 2021.

The dominance of the COVID-19 Delta variant has renewed questions about the impact of K12 school policies, including the role of masks, on disease burden. A recent study showed masks and testing could reduce infections in students, but failed to address the impact on the community, while another showed masking is critical to slow disease spread in communities, but did not consider school openings under Delta. We project the impact of school-masking on the community, which can inform policy decisions, and support healthcare system planning. Our findings indicate that the implementation of masking policies in school settings can reduce additional infections post-school opening by 23-36% for fully-open schools, with an additional 11-13% reduction for hybrid schooling, depending on mask quality and fit. Masking policies and hybrid schooling can also reduce peak hospitalization need by 71% and result in the fewest additional deaths post-school opening. We show that given the current vaccination rates within the community, the best option for children and the general population is to employ consistent high-quality masking, and use social distancing where possible.