Promotion and Application of a New Three-level Etiological Diagnosis Strategy for Fever Clinics in Respiratory Infectious Diseases

Inclusion Criteria: 1. Acute onset within one week; 2. 18-70 years old; 3. Present with pneumonia (present with pulmonary signs or radiological changes) or influenza-like illness (including the following symptoms: sudden onset of fever (\>38 ℃),plus cough and/or other respiratory symptoms such as shortness of breath plus one or more systemic symptoms (fatigue, headache ect.)) Exclusion Criteria: 1. Unable to collect nasal/nasopharyngeal swab/wash/aspirate due to structural disorder or mental problem. 2. Patients with psycological problem or unconsciousness who cannot tell the disease history and cooperate with medical examinations;