New Crown is characterized by fever, dry cough, and malaise. Some patients may have nasal congestion, runny nose, sore throat, decreased or loss of smell and taste, conjunctivitis, myalgia and diarrhea as the main manifestations. 1. Mild patients may present with low-grade fever, mild malaise, smell and taste impairment, etc., without pneumonia. Asymptomatic and mild symptoms are predominant in vaccinated patients and those infected with Omicron. Clinical symptoms mainly include low to moderate fever, dry throat, sore throat, nasal congestion, runny nose, and other symptoms of upper respiratory tract infection. Most patients have a good prognosis, but a few patients are in critical condition, mostly in the elderly, people with chronic underlying diseases, late pregnancy and perinatal women, and obese people. 2. Severe patients mostly have respiratory distress and/or hypoxemia one week after the onset of the disease, and in severe cases, the disease may rapidly progress to acute respiratory distress syndrome, septic shock, metabolic acidosis and coagulation dysfunction, and multi-organ failure, etc. Very few patients may also have centralized respiratory tract infection. Very few patients may also have central nervous system involvement and limb ischemic necrosis. 3. Symptoms in children are relatively mild, and some children and newborns may have atypical symptoms, such as vomiting, diarrhea and other digestive symptoms, or only poor response and shortness of breath. A very small number of children may have multi-system inflammatory syndrome (MIS-C), with manifestations similar to Kawasaki disease or atypical Kawasaki disease, toxic shock syndrome, or macrophage activation syndrome, which mostly occurs during the recovery period. The main manifestations are fever with rash, non-purulent conjunctivitis, mucosal inflammation, hypotension or shock, coagulation disorders, and acute gastrointestinal symptoms. Once it occurs, the condition can deteriorate dramatically in a short period of time.