RT-PCR, it's pretty good but takes time. They just do batch tests and mix samples in groups, if positive, test again. My father did one a few months ago after

RT-PCR, it's pretty good but takes time. They just do batch tests and mix samples in groups, if positive, test again. My father did one a few months ago after returning from Qingdao, where there were a small outbreak then in a hospital. China is really good at doing things at scale and honestly US is nowhere close (too slow and too inefficient, from what I see here in Santa Clara)