Results
A variety of IPC measures (ventilation, hygiene and physical distancing) was implemented by more than 60% of schools, with most attention placed on hygiene measures. In January 2021, poor implementation of IPC measures was associated with an increase in 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 only statistically significant for the assessment of all IPC measures together in the population comprised of pupils and staff.