SARS‑CoV‑2 incidence in secondary schools

SARS‑CoV‑2 incidence in secondary schools: the role of national and school‑initiated COVID‑19 measures

Jonker, Lotte (University Medical Center Utrecht)
Linde, Kimberly J. (Universiteit Utrecht)
de Boer, Annemarijn R. (University Medical Center Utrecht)
Ding, Er (TU Delft Environmental & Climate Design)
Zhang, D. (TU Delft Environmental & Climate Design)
de Hoog, M.L.A. (University Medical Center Utrecht)
Herfst, Sander (Erasmus MC)
Heederik, Dick (Universiteit Utrecht)
Bluyssen, P.M. (TU Delft Environmental & Climate Design)

2023

Introduction: Our aim was to gain insight into the effect of COVID-19 measures on SARS-CoV-2 incidence in secondary schools and the association with classroom CO ₂ concentration and airborne contamination. Methods: Between October 2020—June 2021, 18 schools weekly reported SARS-CoV-2 incidence and completed surveys on school-initiated COVID-19 measures (e.g. improving hygiene or minimizing contacts). CO ₂ was measured in occupied classrooms twice, and SARS-CoV-2 air contamination longitudinally using electrostatic dust collectors (EDC) and analyzed using RT-qPCR. National COVID-19 policy measures varied during pre-lockdown, lockdown and post-lockdown periods. During the entire study, schools were recommended to improve ventilation. SARS-CoV-2 incidence rate ratios (IRR) were estimated by Generalized Estimating Equation (GEE) models. Results: During 18 weeks follow-up (range: 10–22) SARS-CoV-2 school-incidence decreased during national lockdown (adjusted IRR: 0.41, 95%CI: 0.21–0.80) and post-lockdown (IRR: 0.60, 0.39–0.93) compared to pre-lockdown. School-initiated COVID-19 measures had no additional effect. Pre-lockdown, IRRs per 10% increase in time CO ₂ exceeded 400, 550 and 800 ppm above outdoor level respectively, were 1.08 (1.00–1.16), 1.10 (1.02–1.19), and 1.08 (0.95–1.22). Post-lockdown, CO _2-concentrations were considerably lower and not associated with SARS-CoV-2 incidence. No SARS-CoV-2 RNA was detected in any of the EDC samples. Conclusion: During a period with low SARS-CoV-2 population immunity and increased attention to ventilation, with CO ₂ levels most of the time below acceptable thresholds, only the national policy during and post-lockdown of reduced class-occupancy, stringent quarantine, and contact testing reduced SARS-CoV-2 incidence in Dutch secondary schools. Widespread SARS-CoV-2 air contamination could not be demonstrated in schools under the prevailing conditions during the study.

SARS-CoV-2
COVID-19 measures
Secondary schools
Air contamination
CO2 concentration

http://resolver.tudelft.nl/uuid:cd305cd6-21a5-4d92-bcfd-f321125bb0d0

https://doi.org/10.1186/s12889-023-16146-0

BMC Public Health, 23 (1)

Institutional Repository

journal article

© 2023 Lotte Jonker, Kimberly J. Linde, Annemarijn R. de Boer, Er Ding, D. Zhang, M.L.A. de Hoog, Sander Herfst, Dick Heederik, P.M. Bluyssen, More Authors