1.3 Specimen and data collection
Respiratory tract samples were collected from the enrolled patients upon
hospital visit, including oropharyngeal swabs, sputum specimens,
endotracheal aspirates, or bronchoalveolar-lavage specimens. For
inpatients, only specimens obtained within 72 hours before or after
hospital admission were included. Demographic, epidemiological, and
clinical data were collected systematically using standardized forms.