Inclusion Criteria:  Age 18- 60 years old Have been diagnosed as new COVID-19 case by RT-PCR since disease onset to admission less than 7 days Have asymptomatic infection assessed by the World Health Organization (WHO) disease category  Do not have any of following disease or conditions  Body weight > 90 kg or BMI > 30 kg/m2 Hypertension that needs antihypertensive medication Diabetes Cardiovascular diseases including congenital heart disease Cerebrovascular diseases Chronic kidney and chronic liver diseases COPD or chronic lung diseases Lymphocyte <1,000 cells/mm3 Late-stage cancer Auto-immune disease (e.g., SLE, Rheumatoid arthritis, multiple sclerosis, etc.) or currently on immunosuppressive drug Coagulation disorders or platelet disorders and are being treated with anticoagulants such as warfarin, clopidogrel Pregnancy Willing to participate with the study and sign inform consents.  (Withdrawal criteria)  Patients withdraw from the study Have severe adverse effect that may relate to Andographolide or Boesenbergia