Abbott ID NOW Point-of-Care Testing

Inclusion Criteria: * Acute onset of illness with fever (tympanic temperature ≥38°C) persisting for at least 24 hours. * Acute onset of illness accompanied by decreased oxygen saturation (e.g., SpO₂ decreased to 94% or deterioration in oxygenation), or influenza infection highly suspected by the treating physician. * Residents aged 65 years or older with comorbidities (e.g., diabetes mellitus, dialysis, hypertension, heart disease, or use of immunosuppressive agents) who develop acute illness with fever (tympanic temperature ≥37.5°C) persisting for at least 24 hours. * At least one respiratory symptom, such as cough, sore throat, or rhinorrhea, persisting for at least 24 hours. Exclusion Criteria: * A definite alternative diagnosis identified at the initial assessment that explains the influenza-like illness, such as bacterial pneumonia, non-respiratory infection, aspiration pneumonia following choking during feeding, definite urinary tract infection, or known exacerbation of heart failure without evidence of infection. * Refusal by the resident or the resident's legally authorized representative to provide informed consent for data collection. * Expected survival of less than 48 hours, as assessed by a physician. * Participation in this study within the previous 14 days, to avoid duplicate enrollment for the same illness episode. * Residence in a dedicated dementia care unit, because differences in disease characteristics, communication ability, and care practices may affect the internal validity of the study.