School Closure Versus Targeted Control Measures for SARS-CoV-2 Infection.

Objectives: To compare effects of school closures with effects of targeted infection prevention and control (IPC) measures in open schools on SARS-CoV-2 infection rates in students.

Methods: We conducted interrupted time-series analyses to compare trends in infection rates in grades 1-10 in 7 boroughs in Oslo, Norway, between February 15 and April 18, 2021. All schools at all levels had implemented strict IPC measures. While grades 1-4 attended school throughout the study period, school closures were implemented for grades 5-10 from March 17. We obtained individual level data from nationwide registries.

Results: A total of 616, 452, and 446 students in grades 1-4, 5-7 and 8-10, respectively, were registered with a positive SARS-CoV-2 test during the study period, when the α-variant dominated. A statistically significant reduction in postintervention trends was observed for grades 1-4 (coefficient -1.26; 95% confidence interval (CI), -2.44 to -0.09). We did not observe any statistically significant between-group differences in postintervention trends between grades 1-4 and 5-7 (coefficient 0.66; 95% CI, -1.25 to 2.58) nor between grades 1-4 and 8-10 (coefficient -0.63; 95% CI, -2.30 to 1.04). Findings indicate that keeping schools open with strict IPC measures was equally effective as school closures on reducing student infection rates.

Conclusions: School closure was not more effective than targeted IPC measures in open schools in reducing student infection rates. Our findings suggest that keeping schools open with appropriate IPC measures should be preferred over school closures, considering the negative consequences closures have on students.