C hildren have been disproportionately affected by public health measures in the current coronavirus disease (COVID-19) pandemic (1). In contrast to other age groups, children have shown lower rates of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive cases; lower risk for symptomatic, acute, COVID-19; a generally milder course of disease with the exception of some rare manifestations and the post-COVID-19 multisystem infl ammatory syndrome in children; and lower secondary attack rates (2-4). Susceptibility to infection in <10 years of age is estimated to be lower than that for teenagers. Accumulating evidence shows that, given limited infection control measures, SARS-CoV-2 might spread sustainably in secondary/high schools but to a lesser degree in primary schools and nurseries (2,5).Closure of childcare facilities and schools has been shown to negatively affect the physical and emotional well-being of children, teenagers, and parents, potentially having a long-term impact on their lives (6). Thus, various expert groups called for avoiding closing of these institutions (7,8). Against the background of presymptomatic transmission found in adults, it is critical to public health authorities to be able to rely on real-life data monitoring the number of asymptomatic yet infected children attending educational institutions (9). Some studies have reported low numbers of infected cases in primary schools or childcare facilities but were conducted during a lockdown or semi-lockdown period (5,10). The aim of our study (the Münchner Virenwächter Study) was to implement a real-time sentinel program in a representative number of 5 primary schools and 5 (6 in phase 2) nurseries/kindergartens in Munich, Germany. The StudyThis study was approved by the ethics committee of the Ludwig-Maximilians University under project no. 20-484. We intended to accomplish a timely detection of infected cases and offer an additional level of safety to participating institutions during regular operating mode. The study spanned over 2 phases (Figure 1): phase 1, June 15-July 26, 2020; and phase 2, September 7-November 1, 2020. Participating institutions were randomly selected, and written informed consent was obtained in the fi rst week of each phase. To correct for underrepresentation of younger children (<5 years of age), we included an additional nursery/ kindergarten into phase 2.We tested oropharyngeal swab specimens for SARS-CoV-2 by using real-time reverse transcription PCR (rRT-PCR); weekly samples were obtained from randomly selected children (n = 20) and staff (n = 5) in each institution. Swab specimens were taken on-site by trained medical personnel, and results were timely reported. For rRT-PCR, we processed specimens

A 12-week sentinel programme monitored SARS-CoV-2 in primary schools, kindergartens and nurseries. Out of 3169 oropharyngeal swabs, only two tested positive on rRT-PCR while general incidence rates were surging. Thus, children attending respective institutions are not significantly contributing to the pandemic spread when appropriate infection control measures are in place.

Representative, actively collected surveillance data on asymptomatic SARS-CoV-2 infections in primary schoolchildren remain scarce. We evaluated the feasibility of a saliva mass screening concept and assessed infectious activity in primary schools. During a 10-week period from 3 March to 21 May 2021, schoolchildren and staff from 17 primary schools in Munich participated in the sentinel surveillance, cohort study. Participants were tested using the Salivette® system, testing was supervised by trained school staff, and samples were processed via reverse transcription quantitative polymerase chain reaction (RT-qPCR). We included 4433 participants: 3752 children (median age, 8 [range, 6–13] years; 1926 girls [51%]) and 681 staff members (median age, 41 [range, 14–71] years; 592 women [87%]). In total, 23,905 samples were processed (4640 from staff), with participants representing 8.3% of all primary schoolchildren in Munich. Only eight cases were detected: Five out of 3752 participating children (0.13%) and three out of 681 staff members (0.44%). There were no secondary cases. In conclusion, supervised Salivette® self-sampling was feasible, reliable, and safe and thus constituted an ideal method for SARS-CoV-2 mass screenings in primary schoolchildren. Our findings suggest that infectious activity among asymptomatic primary schoolchildren and staff was low. Primary schools appear to continue to play a minor role in the spread of SARS-CoV-2 despite high community incidence rates.

Children have been disproportionately affected during the COVID-19 pandemic. We aimed to assess a saliva-based algorithm for SARS-CoV-2 testing to be used in schools and childcare institutions under pandemic conditions. A weekly SARS-CoV-2 sentinel study in primary schools, kindergartens, and childcare facilities was conducted over a 12-week-period. In a sub-study covering 7 weeks, 1895 paired oropharyngeal and saliva samples were processed for SARS-CoV-2 rRT-PCR testing in both asymptomatic children (n = 1243) and staff (n = 652). Forty-nine additional concurrent swab and saliva samples were collected from SARS-CoV-2 infected patients (patient cohort). The Salivette® system was used for saliva collection and assessed for feasibility and diagnostic performance. For children, a mean of 1.18 mL saliva could be obtained. Based on results from both cohorts, the Salivette® testing algorithm demonstrated the specificity of 100% (95% CI 99.7–100) and sensitivity of 94.9% (95% CI 81.4–99.1) with oropharyngeal swabs as reference. Agreement between sampling systems was 100% for moderate to high viral load situations (defined as Ct-values <33 from oropharyngeal swabs). Comparative analysis of Ct-values derived from saliva vs. oropharyngeal swabs demonstrated a significant difference (mean 4.23; 95% CI 2.48–6.00). In conclusion, the Salivette® system proved to be an easy-to-use, safe and feasible saliva collection method and a more pleasant alternative to oropharyngeal swabs for SARS-CoV-2 testing in children aged 3 years and above.

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