Originally Posted by NickB

But what would be the point of tracing people in the country when you have massive domestic community spread? I had made some calculations in the UK back in January where we were in a similar position to that of France now and, for every case of infection attributable to imported cases, we were more than two orders of magnitude in the number of infections attributable to domestic transmission. At that level, it is utterly pointless to try to stop imported cases of infection as they make a negligible contribution to the spread of the infection. Control of inbound infections only starts to make a sensible contribution once you have largely eradicated domestic spread, like Asian and Australasian countries have done. Until then, for a state of average to large size, it is just a waste of time (and hence why, incidentally, the current restrictions of leaving and entering France from third countries are meaningless but that is another issue).