The average time to rule out a suspected case of New Crown is at least 14 days. According to the national protocol, the first step to exclude a suspected case is to pass the incubation period (at least 14 days), and during this period, at least two negative nucleic acid tests are required, and the second time to collect the test samples should be 24 hours after the first collection, so the average exclusion of a suspected case takes at least 14 days. The following requirements are currently needed for exclusion of suspected cases: 1. at least two consecutive negative nucleic acid test results, and the time between samples must not be less than twenty-four hours; 2. it must be combined with clinical signs and symptoms as well as imaging; 3. It needs to be determined by a comprehensive expert consultation. So it also takes some time. Because the new crown virus is the existence of the incubation period, that is to say, when the pathogen infection of the human body will not immediately after the onset of the disease, and from infection to the onset of this period of time is called the incubation period. At present, the incubation period of the new coronavirus is at least 14 days, the incubation period of its nucleic acid test results may also be negative, the patient may not have any discomfort symptoms, in summary, to rule out the new coronavirus suspected patients need at least 14 days.