The effect of in-person primary and secondary school instruction on county-level SARS-CoV-2 spread in Indiana

Background: The effect of in person primary and secondary school instruction on the community transmission of SARS-CoV-2 remains unclear. Objective: To determine the county-level effect of in-person primary and secondary school reopening on daily cases of SARS-CoV-2 in Indiana. Design: Panel data regression analysis utilizing the proportion of in-person learning to evaluate an association with community-wide daily new SARS-CoV-2 cases. The study period was July 12-October 6, 2020. Setting: A county-level population-based study. Participants: We included 73 out of 92 (79.3%) Indiana Counties in the analysis, accounting for 85.7% of school corporations and 90.6% of student enrollement statewide. Main outcomes and measures: The primary exposure was the proportion of students returning to in-person instruction. The primary outcome was the daily new SARS-CoV-2 cases per 100,000 residents at the county level. Results: There is a statistically significant relationship between the proportion of students attending K-12 schools in-person and the county level daily cases of SARS-CoV-2 28 days later. For all ages, the coefficient of interest ({beta}) is estimated at 3.36 (95% CI: 1.91-4.81; p < 0.001). This coefficient represents the effect of a change the proportion of students attending in-person on new daily cases 28 days later. For example, a 10 percentage point increase in K-12 students attending school in-person is associated with a daily increase in SARS-CoV-2 cases in the county equal to 0.336 cases/100,000 residents of all ages. Limitations: Single state study; inability to stratify school age effects by age; cannot account for non-linear growth effects. Conclusion and relevance: In-person primary and secondary school is associated with a statistically significant but proportionally small increase in the spread of SARS-CoV-2 cases.