The clinical manifestations of delta virus infection do not differ significantly from those caused by previous strains, and remain some of the familiar symptoms of infection, i.e., fever, dry cough, and malaise as the main manifestations. In some patients, the first manifestation is loss of smell and taste or loss of taste. A few patients may present with nasal congestion, runny nose, sore throat, conjunctivitis, myalgia and diarrhea. Severely ill patients tend to develop respiratory distress and/or hypoxemia 1 week after the onset of the disease, which can rapidly progress to acute respiratory distress syndrome, septic shock, metabolic acidosis, bleeding and coagulation disorders, and multi-organ failure in severe cases. Very few patients may also show central nervous system involvement and ischemic necrosis of the extremities. However, unlike previous strains, delta virus is significantly more transmissible, its transmission capacity has doubled, and the incubation period or transmission interval has shortened, and the rate of transmission is accelerating. At the same time, the viral load of delta virus was significantly increased and the time required for nucleic acid conversion of patients was prolonged.