Measures for infection prevention and control of SARS-CoV-2 in Belgian schools between December 2020 and June 2021: a prospective cohort study

Introduction As the role of school-aged children was unclear at the onset of the COVID-19 pandemic, public health authorities recommended to implement infection prevention and control (IPC) measures in school settings. Few studies evaluated the implementation of these measures and their effect on SARS-CoV-2 infection rates among pupils and staff. Aim To describe the implementation of IPC measures in Belgian primary and secondary schools and assess its relation to the prevalence of anti-SARS-CoV-2 antibodies among pupils and staff. Methods We conducted a prospective cohort study in a representative sample of primary and secondary schools in Belgium. Implementation of IPC measures in schools was assessed using an online questionnaire. Saliva samples were collected from pupils and staff to determine the SARS-CoV-2 seroprevalence. Results A variety of IPC measures (ventilation, hygiene and physical distancing) was implemented by more than 60% of primary and secondary schools with most attention for hygiene measures. Almost no differences in implementation coverage were observed between primary and secondary schools or the Dutch and French language network. Poor implementation of IPC measures was associated with an increased anti-SARS-CoV-2 antibody prevalence among pupils from 8.6% (95% CI: 4.5 - 16.6) to 16.7% (95% CI: 10.2 - 27.4) and staff from 11.5% (95% CI: 8.1 - 16.4) to 17.6% (95% CI: 11.5 - 27.0). This association was statistically significant for all IPC measures and pupils and staff combined. Conclusion Belgian schools were relatively compliant with recommended IPC measures at the school level. Poor implementation of IPC measures was associated with higher SARS-CoV-2 seroprevalence among pupils and staff. Trial registration number Trial registration number: NCT04613817