Study on Prevention of SARS-CoV-2 Transmission During a Large Indoor Gathering Event

The objective is to demonstrate if there is no increase in the risk of Sars-Cov-2 salivary carriage 7 days after a concert in the group participating in the event compared to a non participating group who stayed at home. The hypothesis is that a systematic screening of Sars-Cov-2 within the 3 days before the event allows to control the risk of transmission and prevent cluster of transmission during the concert.

Before inclusion, the participants will be able to pre-register to the event via a website. They will get an appointment for an inclusion visit at the Accor Arena (Paris Bercy, France). During 3 days (from D-3 to D-1), participants with a registration will come to the Accor Arena to have a rapid Sars-Cov-2 antigen test (results in 15 min). If the test is positive, the participant will be contacted and managed by the medical team in charge of the national strategy for positives cases. People with a negative test will be included and randomized : * Two kits with tube for collecting saliva samples (for D0 and D7) will be given to each participant at this visit * People randomized in the experimental group will receive their concert ticket at a later date. * At Day 0, people randomized in the experimental group, will come to the Accor Arena with their ticket to participate in the concert. At the entrance, they should give their D0 saliva sampling kit. The people randomized in the control group will stay at home and will send their D0 saliva sample by post mail. * At Day 7 (±1 day) all the participants must return their D7 saliva sampling kit via post mail