Before revision:  We conclude that Covid-19 is much more spread than previously thought, but its severity became very limited since the end of the first wave . The level of spreading raises doubts in the large-scale testing strategy which anyway detects only a few percents of infected people. It also raises doubts in the efficiency of the closing of school classes, where a pupil is tested Covid-positive by chance. Finally, determining the probability of reinfection by making a large-scale testing of persons already found positive several months ago would strongly help to get a better visibility of the future outbreak trajectory .
After revision:  We conclude that Covid-19 is much more spread than previously thought, but its severity became very limited since the end of the first wave .