Its clinical classification [4] mainly includes the mild type (with mild clinical symptoms, no pneumonia on imaging), common type (with clinical symptoms such as fever and respiratory diseases and with findings of pneumonia on imaging), severe type, and critical type; asymptomatic carriers [5, 6] refer to those individuals who have no clinical symptoms (such as fever, cough, and sore throat) but have positive pathogenic or serum specific IgM antibodies in the respiratory tract or other origin samples, and asymptomatic carriers can also be sources of infection. This evidence concerns the gene CD40LG and susceptibility to pneumonia measurement.