Comment by makomk

Like a lot of the Chinese solutions to Covid-19, this is interesting because it really shouldn't work. We know that these kinds of swab tests have a fairly substantial false negative rate - initially from Chinese research, and then I think confirmed pretty much everywhere else - especially when trying to detect pre-symptomatic carriers of the disease. (Also, based on other results elsewhere, I think we'd expect to see a few people out of a Wuhan-sized outbreak testing positive even if they'd long since recovered from the disease and were no longer infectious.)