Definitions
Acute respiratory illness (ARI) was defined as a new onset of cough or
worsening of a chronic cough. Severe ARI (SARI) was defined as an
illness requiring hospitalization with measured axillary temperature
≥38°C plus a new onset of a cough, worsening of a chronic cough, or
difficulty in breathing. Cardiopulmonary condition was defined as the
presence of any known physician-diagnosed chronic cardiovascular
conditions (such as coronary artery diseases, cardiac arrhythmias,
valvular heart diseases, cardiomyopathy) and/or any chronic lung
diseases (such as chronic obstructive pulmonary disease (COPD), asthma,
chronic bronchitis, pulmonary tuberculosis, emphysema, and lung
fibrosis).