Generally, most patients can be detected after the onset of symptoms of neocrown pneumonia, i.e., after a 3-7 day incubation period. The detection of Wuhan pneumonia now includes pharyngeal swab nucleic acid testing and chest CT testing, routine blood tests, all three combined and then evaluated with symptoms and epidemiological history. The most specific test, the pharyngeal swab nucleic acid test, is a confirmatory tool. It usually takes at least 3 days after infection for nucleic acid to appear in the pharynx, and the initial low nucleic acid load may lead to undetection and the need for repeat testing. If there are clinical symptoms but the test is negative, it cannot be easily ruled out and a repeat test is required. Usually after 7 days, if two consecutive negative tests are performed, the infection can be considered absent. With advances in testing, blood antibody testing has been added. It is usually considered that infection can be ruled out in suspected cases with two negative pharyngeal test nucleic acid tests with an interval of 24 hours, plus a test still negative for antibodies more than 7 days after the onset of the disease. If infection is present, the vast majority of patients will test positive within 7 days. Content source: Dr. You Lai