Prevalence of RT-PCR-detected SARS-CoV-2 infection at schools: First results from the Austrian School-SARS-CoV-2 Study

Background: There is much debate about the role of schools and children in the SARS-CoV-2 pandemic. We aimed to quantify reliably the prevalence of SARS-CoV-2 infections at schools detected with reverse-transcription polymerase-chain-reaction (RT-PCR). Methods: This nationwide prospective cohort study monitors a representative sample of pupils (grade 1-8) and teachers at Austrian schools throughout the school year 2020/2021. We repeatedly test participants for SARS-CoV-2 infection using a gargling solution and RT-PCR. We herein report on the first two rounds of examinations. We used mixed-effect logistic regression to estimate odds ratios and robust 95% confidence intervals (95% CI). Findings: We analysed data on 10734 participants from 245 schools (9465 pupils, 1269 teachers). Prevalence of RT-PCR-detected SARS-CoV-2 infection increased from 0.39% at round 1 (95% CI 0.28-0.55%, 29 September-22 October 2020) to 1.42% at round 2 (95% CI 1.06-1.90%, 10-16 November). Odds ratios for SARS-CoV-2 infection were 2.29 (95% CI 1.26-4.17, P=0.007) in regions with >500 vs. [≤]500 inhabitants/km2, 1.69 (95% CI 1.42-2.00, P<0.001) for a two-fold higher regional 7-day incidence, and 2.71 (95% CI 1.68-4.39, P<0.001) in pupils at schools with a high/very high vs. low/moderate social deprivation index. Associations of community incidence and social deprivation persisted in multivariable models. There were no differences between age groups, sexes, pupils vs. teachers, or primary (grade 1-4) vs. secondary schools (grade 5-8). Interpretation: This monitoring study in Austrian schools revealed SARS-CoV-2 infection in 0.39%-1.42% of participants and identified associations of regional community incidence and social deprivation with higher prevalence.