This study intends to observe the immune typing of peripheral blood lymphocytes and differential changes in the levels of interleukin-2 (IL-2), IL-4, IL-6, IL-10, tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) in children with severe adenovirus infection to explore the infection mechanism of adenovirus from cytokine levels and whether it can help early diagnosis and prognosis prediction of severe adenovirus pneumonia. Here, TNF is linked to infection.