The incubation period of pneumonia in Wuhan is considered to be 3-7 days according to the diagnosis and treatment program of the new crown pneumonia issued by the current Health Commission, and the average should be about 4 days, but from the clinical observation, the onset of the disease within 14 days is still relatively common, and there are even a small number of onset of the disease within 28 days. From the laboratory examination, it takes 4 days for the virus to be detected from the human respiratory tract in the laboratory, and these 4 days are still the incubation period. Therefore, this 4-day period is consistent with the 4-day onset of illness observed in the clinic, and the incubation period is still considered to be around 4 days. However, it is important to note that the exposure history of some patients is not entirely conclusive, so the onset of the disease is more likely to be predominantly within 1-2 weeks, so a two-week observation period is still very necessary. Source: Dr. Yurai