Confirmation of the diagnosis of pneumonia with novel coronaviruses requires a positive nucleic acid test or a positive antibody test in addition to the suspected case. If IgM and IgG antibody positivity can confirm the diagnosis, or if progressive elevation, especially 4-fold elevation, is found after two IgG tests, it can be used as a confirmed case. However, two comparisons are required and its consumes a long time. The simplest is the nucleic acid test. Nucleic acid tests are usually performed after the specimen is collected and sent to a laboratory, which takes about 4 hours to produce the results. Therefore, the definitive diagnosis of a case is first made on the basis of a suspected case and then a nucleic acid test is performed, which takes about 4 hours to obtain a definitive result. The diagnosis of a suspected case is based on epidemiologic history and symptoms. The time to diagnose a suspected case depends on the length of the incubation period. The incubation period is the time between infection and the onset of symptoms, which is usually 2-14 days, but in most people it is 3-7 days, i.e. the fastest time for symptoms to appear is 3 days after infection, and the doctor will judge it to be a suspected case, and then do the nucleic acid test in about 4 hours. That is, it usually takes more than 3-4 days to make a diagnosis. Content source: Dr. Yurai