Severe community-acquired pneumonia caused by adenovirus (hereafter referred to as severe adenovirus pneumonia) is one of the common forms of severe community-acquired pneumonia in immunocompetent adults. It predominantly affects young individuals, progresses rapidly, and is associated with a high incidence of respiratory failure and multiple organ dysfunction. At present, there is no effective antiviral therapy available in China, and the reported mortality rate ranges from 41.5% to 80%. How to effectively reduce the mortality of severe adenovirus pneumonia, on the basis of conventional supportive care, is crucial for improving the prognosis of critically ill patients and alleviating the burden on families and society. We are currently conducting an adaptive, randomized, open-label controlled trial aimed at reducing mortality in severe adenovirus pneumonia. The primary objective of this study is to evaluate the efficacy and safety of adjunctive corticosteroid therapy at different dosages, in addition to early standard supportive treatment, in lowering mortality among patients with severe adenovirus pneumonia.

Inclusion Criteria:

• Age ≥ 18 years.

• Admission to the Intensive Care Unit (ICU).

• Meeting the diagnostic criteria for community-acquired pneumonia (CAP).

• Meeting at least one of the major diagnostic criteria for severe pneumonia:

  (i) Requirement for endotracheal intubation and mechanical ventilation;

(ii) Septic shock requiring vasopressor therapy after adequate fluid resuscitation.

-Or simultaneously fulfilling three of the minor criteria:

(i) Respiratory rate ≥ 30 breaths/min;

(ii) PaO₂/FiO₂ ≤ 250 mmHg;

(iii) Multilobar infiltrates;

(iv) Altered mental status and/or disorientation;

(v) Blood urea nitrogen ≥ 20 mg/dL (7.12 mmol/L);

(vi) Leukopenia (white blood cell count < 4 × 10⁹/L);

(vii) Thrombocytopenia (platelet count < 100 × 10⁹/L);

(viii) Hypothermia (core temperature < 36 °C);

(ix) Hypotension (systolic blood pressure < 90 mmHg) requiring aggressive fluid resuscitation.

• Confirmed adenovirus etiology: at least one positive nucleic acid test (PCR) or next-generation sequencing (NGS) result for adenovirus in respiratory specimens (respiratory secretions, throat swabs, or bronchoalveolar lavage fluid).
• Severe community-acquired pneumonia (SCAP) patients admitted to the emergency department/ward/ICU due to respiratory failure within < 72 hours.
• Signed informed consent.

Exclusion Criteria:

• Patients receiving vasopressor therapy for septic shock at the time of enrollment.
• Terminally ill patients (expected survival <30 days, e.g., advanced malignancy).
• Clinical history suggesting overt aspiration.
• Documented active gastrointestinal bleeding.
• Presence of cystic fibrosis, obstructive pneumonia, active influenza, pulmonary tuberculosis, or fungal infection.
• Active viral hepatitis or active herpesvirus infection.
• Bone marrow suppression or HIV infection.
• Refusal of mechanical ventilation and endotracheal intubation.
• Uncontrolled hyperglycemia (diabetic ketoacidosis with blood ketones >3 mmol/L, or hyperosmolar hyperglycemic state with blood glucose >33.3 mmol/L and elevated osmolality).
• Known allergy to corticosteroids.
• Patients requiring anti-inflammatory corticosteroids or replacement hydrocortisone for any reason, or those already receiving prednisone >15 mg/day (or equivalent dose of another corticosteroid).
• Pregnant or breastfeeding women.