[School-based screening strategies to prevent the spread of COVID-19 in school: a systematic review of the literature]

Objectives: to describe studies that evaluated the screening programmes implemented in the school during the COVID-19 pandemic.

Design: a systematic literature review was conducted according to the PRISMA 2020 Guidelines. Studies published until December 2021 were included. The methodological quality of the studies was assessed with validated scales. Study selection, data extraction, and quality assessment were carried out by two authors independently.

Setting and participants: teachers and students belonging to schools of all levels, including universities.

Main outcomes measures: a. transmission-related outcomes (such as the number or proportion of cases, cumulative frequency, incidence); b. feasibility/acceptability of the screening strategies; c. socioeconomic outcomes (such as testing cost, number of days spent in school, quarantine).

Results: after having removed duplicate articles, 2,822 records were retrieved. Thirty-six studies were included (15 used an observational design and 21 modelling study). Regarding the former, the methodological quality has been rated as high in 2 studies, intermediate in 6 and low in 2; in the remaining ones, it was not evaluated because only descriptive. Screenings were quite different in terms of school study population, types of tests used, methods of submission and analysis, and level of incidence in the community at the time of implementation. Outcome indicators were also varied, a heterogeneity that, on the one hand, did not allow for meta-analysis of results and, on the other, allowed for testing the performance of the screenings in very different settings. All of the field studies claim that the screenings reduced SARS-CoV-2 exposure and infection among children, adolescents, and college students, curbing at-school transmission and helping to reduce the number of closing school days. Studies that evaluated the cost of the intervention emphasized its cost-effectiveness, while those that focused on the acceptability of the instrument showed a preference among children, adolescents, and parents for minimally invasive, self-administered tests with high sensitivity and lower frequency of repetition. Simulation-based studies are mostly based on compartmental and agent-based models. Their quality is quite high methodologically, although uncertainty quantification and external validation, aimed at verifying the model ability to reproduce observed data, are lacking in many cases. The contexts to which the simulations refer are all school-based, although 7 studies consider residential situations, which are poorly suited to the Italian context. All simulation-based models indicate the importance of planning repeated testing on asymptomatic individuals to limit contagion. However, the costs of these procedures can be high unless assessments are spaced out or pool testing procedures are used. Obtaining high student adherence to the screening programme is extremely important to maximize results.

Conclusions: school-based screenings, especially when combined with other preventive measures, have been important public health tools to contain infections during COVID-19 waves and to ensure children's and adolescents' right to education and to prevent the fallout in physical and mental health (with strong equity consequences) associated with school closures.