In this clinical trial, the aim is to determine if regular screening with pooled saliva tests (Lolli-Method) is useful to support school opening and to reduce clusters and attack rates in schools, compared with the standard of care (SoC) regular surveillance based on symptoms and contact tracing by public health departments.

In this clinical trial, it will be determined if regular screening with pooled saliva tests (Lolli-Method) is useful to support school opening and to reduce clusters and attack rates in schools, compared with the standard of care (SoC) regular surveillance based on symptoms and contact tracing by public health departments. A multicenter cluster randomised interventional study will be set-up to evaluate the efficacy and applicability of the Lolli-Methode. The study will enrol 440 classes (around 8800 students, teachers and other personnel) from 2 countries, randomised to Lolli-Methode or SoC. Samples from pools will be regularly collected and tested using PCR-based techniques. Test results will be combined with questionnaires filled in by children, parents and schools teachers and principals, concerning social distancing measures implemented and psychological impact of the preventive measures applied during the pandemic. A thorough data analysis will then be performed to understand the applicability of Lolli-Methode to reduce SARS-COV-2 transmission in schools, including incidence, attack rates and cluster analysis. On the other hand, mobility changes and psychological outcomes will be analysed and compared with variables related to SARS-COV-2 transmission. By the end of this study, it will be identified and characterised the applicability of the Lolli-Methode for SARS-COV-2 surveillance, as well as the impact of pandemic preventive measures on children.

An ancillary observational study will be carried out on a different population of schools to study the prevalence of SARS-COV-2, frequencies and size of clusters and attack rates in schools, compared with those of previous waves; to compare the effectiveness of different preventive measures adopted in different schools; to investigate psychological issues in students and teachers related to the pandemic's containment measures.

Inclusion Criteria:

• Kindergartens and school-age children from public or private schools .
• Enrolled children may be students of classes that have expressed their consent to participate
• School personnel of participating schools
• Householders of participating children
• Informed consent (for minors the informed consent will be signed by parents or legal guardians) .
• For minors: will to participate.

Exclusion Criteria:

• No informed consent by schools or children, or the adult participant
• Suspicion of acute COVID-19 infection:

In case of unknown respiratory infection, no presence of symptoms for at least 48 hours. In case of confirmed SARS-COV-2 infection: inclusion at the earliest 21 days from PCR-positive diagnosis after the onset of potential symptoms and no presence of symptoms for at least 48 hours (according to Standard of Care).

The study is part of a project funded by the European Commission and the project agreement with the Commission affirms that the data and the results will be public

after the Study end no time limit was fixed

request to the study coordinator or to he project partners