You only test people who are sick. You don’t test an entire population.
And it seems right now there’s a shortage of test kits.
Just read that he UK tested 14 people who came back negative.
The point is there is no way yet to determine who is sick until the symptoms manifest, especially the lack of fever makes it near impossible - thus, you have to check the entire population every 14 days which is impossible.
Please sent further inquiries to the Chinese Peoples Liberation Army bio-hazard division.