An intense debate on school closures to control the COVID-19 pandemic is ongoing in Europe. We prospectively examined transmission of SARS-CoV-2 from confirmed paediatric cases in Norwegian primary schools between August and November 2020. All in-school contacts were systematically tested twice during their quarantine period. With preventive measures implemented in schools, we found minimal child-to-child (0.9%, 2/234) and child-to-adult (1.7%, 1/58) transmission, supporting that under 14 year olds are not the drivers of SARS-CoV-2 transmission.

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The role of children in the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in schools has been a topic of controversy. In this study among school contacts of SARS-CoV-2 positive children in 43 contact-investigations, we investigated SARS-CoV-2 transmission in Norway, August 2020–May 2021. All participants were tested twice within seven to ten days, using SARS-CoV-2 PCR on home-sampled saliva. Positive samples were whole genome sequenced. Among the 559 child contacts, eight tested positive (1.4%, 95% CI 0.62–2.80), with no significant difference between primary (1.0%, 95% CI 0.27–2.53) and secondary schools (2.6%, 95% CI 0.70–6.39), p = 0.229, nor by viral strain, non-Alpha (1.4%, 95% CI 0.50–2.94) and Alpha variant (B.1.1.7) (1.7%, 95% CI 0.21–5.99), p = 0.665. One adult contact (1/100) tested positive. In 34 index cases, we detected 13 different SARS-CoV-2 Pango lineage variants, with B.1.1.7 being most frequent. In the eight contact-investigations with SARS-CoV-2 positive contacts, four had the same sequence identity as the index, one had no relation, and three were inconclusive. With mitigation measures in place, the spread of SARS-CoV-2 from children in schools is limited. By excluding contact-investigations with adult cases known at the time of enrolment, our data provide a valid estimate on the role of children in the transmission of SARS-CoV-2 in schools.

A feasibility study was performed to examine the effectiveness of hair testing in determining the prevalence of drug use in a young adult population. The study included 200 randomly selected young adults in Norway. It was designed to make the collection, preparation and analysis of the samples as little resource demaning as possible. Full anonymity was provided for the participants. In total, 23.5% of the samples were positive for one or more substances (14.5%, excluding the nicotine metabolite cotinine). Of the samples, 5% were positive for at least one illegal drug, 9.5% for a medicinal drug, 11.5% for cotinine and 2.5% for the alcohol metabolite ethyl glucuronide. The preliminary findings suggest that the study protocol used to collect and analyze the samples was unable to produce results that could be generalized to the young adult population in Norway. Analysis of hair samples may underestimate the use of cannabis, alcohol, amphetamine and methamphetamine. It may, however, be done to estimate cocaine and general drug use if a sample-collection procedure different from that described in our study is used and includes information about hair length, sample length, length from the scalp, cosmetic treatment, washing and whether the samples always get washed/decontaminated prior to analysis.