Genotype and Disease Burden of RSV in Older Vietnamese Adults (RSV: Respiratory Syncytial Virus )

Inclusion Criteria: To be enrolled in the study, participants must meet all inclusion criteria: 1. Individuals ≥ 60 years old at the time of screening (calculated from the date of birth to the date of screening) 2. ARI or exacerbation of cardiopulmonary diseases diagnosed at the time of admission. ARI or ARI-compatible symptoms were defined as either: * New onset or increase from baseline of: nasal congestion, rhinorrhea, sore throat, hoarseness, cough, sputum production, dyspnea, wheezing, hypoxemia, or * Admitting diagnosis suggestive of ARI (e.g., pneumonia, upper respiratory infection, bronchitis, influenza, cough, viral respiratory illness, respiratory distress, or respiratory failure), or * Admitting diagnosis was the exacerbation of an underlying cardiac or pulmonary disease involving acute respiratory symptoms within the previous 2 weeks (e.g., congestive heart failure \[CHF\], chronic obstructive pulmonary disease \[COPD\], or asthma exacerbation). 3. The participant agrees to voluntarily participate in this study. Exclusion Criteria: To be enrolled in the study, participants must have none of the exclusion criteria: 1. Symptom onset \> 6 days prior to screening date 2. Acute symptoms confirmed to be unrelated to infection or as assessed by the investigator 3. Admission to any hospital within the 30 days preceding the screening date 4. Previously enrolled in the study in the last 45 days