> Using PCR tests to evaluate clearance doesn't make sense though, since they can be positive if there are fragments but no viable virus. It's a cost and time

> Using PCR tests to evaluate clearance doesn't make sense though, since they can be positive if there are fragments but no viable virus. It's a cost and time issue. The cost of filtering snot, inoculating a culture dish of infectable cells with the filtered snot, waiting a couple of days for the cells to show signs of infection (cell swelling or bursting), and then running a PCR test on the cells in the culture dish. With high enough throughput you could probably do this for $50 or there about, and maybe three days, to verify whether they were technically still infected three days ago.