COVID-19 Projections for K12 Schools in Fall 2021: Significant Transmission without Interventions

Abstract

Background: Millions of primary school students across the United States are about to return to in-person learning. Amidst circulation of the highly infectious Delta variant, there is danger that without the appropriate safety precautions, substantial amount of school-based spread of COVID-19 may occur. Methods: We used an extended Susceptible-Infected-Recovered computational model to estimate the number of new infections during 1 semester among a student population under different assumptions about mask usage, routine testing, and levels of incoming protection. Our analysis considers three levels of incoming protection (30%, 40%, or 50%; denoted as "low", "mid", or "high"). Universal mask usage decreases infectivity by 50%, and weekly testing may occur among 50% of the student population; positive tests prompt quarantine until recovery, with compliance contingent on symptom status. Results: Without masking and testing, more than 75% of susceptible students become get infected within three months in all settings. With masking, this values decreases to 50% for "low" incoming protection settings ("mid"=35%, "high"=24%). Testing half the masked population ("testing") further drops infections to 22% (16%, 13%). Conclusion: Without interventions in place, the vast majority of susceptible students will become infected through the semester. Universal masking can reduce student infections by 26-78%, and biweekly testing along with masking reduces infections by another 50%. To prevent new infections in the community, limit school absences, and maintain in-person learning, interventions such as masking and testing must be implemented widely, especially among elementary school settings in which children are not yet eligible for the vaccine.

MITIGATING THE 4th WAVE OF THE COVID-19 PANDEMIC IN ONTARIO

“…Our projections are consistent with other modelling projections. For example, without additional contact reduction and without responsive behaviour change, we estimate 50% to 60% of children under 17 years will become infected over the fall term, consistent with an analysis of school-based transmission that estimated 50% of susceptible children would become infected at school over the fall term with universal masking and low-levels (30%) of vaccine protection [63]. We estimate that a 25% contact reduction leads to approximately 5.4% of the post-secondary student population becoming infected over the term, even with a 98% vaccination rate, consistent with the projection from a model of COVID-19 transmission on college campuses [61].…”

Vaccinating Children Against COVID-19 is Essential Prior to the Removal of Non-Pharmaceutical Interventions

“…We used an agent-based, Susceptible-Exposed-Infected-Recovered simulation model [12,26] with an embedded household, peer group, and community interaction network to evaluate the joint impact of mask compliance in schools and rates of vaccination for children (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19), adults , and 65+ on community transmission, as measured by infections and severe cases requiring hospitalization or resulting mortality. The model was populated with 1,017,720 agents using census-tract level data for the 10.5 million population of North Carolina.…”

“…Previous work has shown masks are effective at slowing infection transmission in the community and schools [ 11 ] and that increased vaccine uptake is required to reduce infections when NPIs, such as masks, are lifted [ 12 ]. In the face of slowing vaccination among previously eligible individuals and more transmissible variants, studies need to estimate the impacts of alternate child-facing interventions (NPIs and vaccination) on community transmission and COVID outcomes to inform decision making.…”

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. 1 A recent study showed masks and testing could reduce infections in students, but failed to address the impact on the community, 2 while another showed masking is critical to slow disease spread in communities, but did not consider school openings under Delta. 3 We project the impact of school-masking on the community, which can inform policy decisions, and support healthcare system planning.…”