We don’t really know that. However, there are strong indications that PCR false negatives can happen quite a lot late during the illness. Those aren’t re-infe

We don’t really know that. However, there are strong indications that PCR false negatives can happen quite a lot late during the illness. Those aren’t re-infections, that's just PCR testing at and around the detection limit. See these graphs from the Munich cluster in Germany: https://twitter.com/c_drosten/status/1249791222526468099 https://twitter.com/c_drosten/status/1249791222526468099