In novel coronavirus pneumonia, the blood counts often show a decrease in the number of lymphocytes, due to the fact that the main inflammatory cells responsible for clearing the virus from the body after it has infected the body, are lymphocytes. If a large amount of virus accumulates in the lungs, a large number of lymphocytes will accumulate in the lungs, causing a decrease in the number and percentage of lymphocytes inside the peripheral blood. When evaluating the severity of a patient, the number of lymphocytes as well as the absolute value and percentage are very important indicators, which, when combined with the patient’s symptoms, as well as age, underlying disease, etc., are very important indicators of the patient’s prognosis and the effectiveness of his or her future treatment.