2.3 Data Collection
Data extracted from patient medical records with a standard case report form included demographic details, patient comorbidities (see Supplementary Material 3), patient symptoms, vital signs, laboratory results, radiographic findings before invasive ventilation at the day of admission (if there were multiple results, the worst value was extracted), community-acquired co-infecting respiratory pathogens, patient management, and outcome data (including NAI use, antibiotic use, systemic corticosteroid administration, IMV, and 14-day mortality). Outcomes for those hospitalized for < 14 days were established through follow-up via telephone.