Massive study aims to unlock Pneumonia's secrets

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

1. Inclusion and Exclusion Criteria for Pneumonia Patients 1.1 Inclusion Criteria 1) Age ≥ 18 years old; 2) Meeting the diagnostic criteria for pneumonia (acute onset + new infiltrates on imaging); 3) Time from onset to admission ≤ 72 hours; 4) Signed written informed consent. 1.1.1 Inclusion Criteria for Severe Pneumonia Patients A diagnosis of "severe pneumonia" can be made if one of the main criteria or ≥ 3 of the secondary criteria are met. Main Criteria: ① Requires mechanical ventilation with tracheal intubation ② Requires vasopressor drugs after aggressive fluid resuscitation for septic shock Secondary Criteria: * Respiratory rate ≥ 30 breaths/min * PaO₂/FiO₂ ≤ 250 mm Hg * Multiple lobe infiltrates * Confusion and/or disorientation ⑤ Blood urea nitrogen ≥ 20 mg/dL ⑥ Leukopenia (WBC \< 4×10⁹/L) ⑦ Thrombocytopenia (PLT \< 100×10⁹/L) ⑧ Decreased body temperature (central body temperature \< 36 ℃) ⑨ Hypotension requiring fluid resuscitation 1.2 Exclusion Criteria 1. End-stage diseases (such as expected survival \< 48 hours); 2. Long-term immunosuppressive therapy (prednisone \> 20mg/d for more than 3 weeks, or neutropenia after chemotherapy); 3. Pregnant or lactating women. 2. Inclusion and Exclusion Criteria for Patients with Suspected Infection but Negative Pathogen Testing 2.1 Inclusion Criteria <!-- --> 1. Age ≥ 18 years old; 2. Having infection-related symptoms or signs (such as fever, cough, sputum production, elevated white blood cells, etc.), clinically suspected of pneumonia; 3. All pathogen tests are negative within 3 days after admission; 4. Time from onset to admission ≤ 72 hours; 5. Signed written informed consent. 2.2 Exclusion Criteria <!-- --> 1. End-stage diseases (such as expected survival \< 48 hours); 2. Long-term immunosuppressive therapy; 3. Pregnant or lactating women;