The incubation period of novel coronavirus infection is generally 3-7 days, with a maximum of 14 days. The main symptoms are fever, malaise, dry cough, and in a few patients, nasal congestion, runny nose, and diarrhea. Severe patients tend to develop respiratory distress after 1 week, and severe cases progress rapidly to acute respiratory distress syndrome, septic shock, uncorrectable metabolic acidosis and coagulation dysfunction. However, it is noteworthy that heavy and critically ill patients may present with moderate to low fever, or even no significant fever. Some patients may present with only low-grade fever and mild malaise without pneumonia manifestations, and mostly recover after 1 week.