The results of this study show that the PCT level (5.9 ± 2.7 vs. 0.9 ± 0.4, P < 0.001) of children with severe adenoviral pneumonia is significantly higher than that of the nonsevere group, which is considered for severe adenoviral pneumonia combined with multiple pathogenic infections (16.30% vs. 9.84%). The gene discussed is CALCA; the disease is infection.