The onset of novel coronavirus infection is usually about 3-7 days after infection, but there are also long cases with onset of more than 14 days and short cases with onset of one day. The onset of novel coronavirus pneumonia infection, that is, the incubation period, generally 3-7 days after infection, fever, dry cough, malaise, some patients with reduced or lost sense of smell and taste as the first symptoms, patients can be accompanied by nasal congestion, runny nose, sore throat, muscle aches, diarrhea and other symptoms, severe patients generally in about a week will develop respiratory distress and hypoxemia, serious will progress to acute respiratory distress Severe cases will progress to acute respiratory distress syndrome, septic shock, and even multi-organ failure leading to death. The length of time after infection with novel coronavirus is related to the patient’s immunity and the virulence and quantity of the infected virus. If it is a mutated virus with a high quantity of virus, elderly people usually have a short incubation period and the onset of the disease will occur soon. If the immunity is stronger, the person can show asymptomatic infection, and the onset time is usually longer.