Inclusion criteria  Confirmed COVID-19 patients by RT-PCR Clinically suspected COVID-19 patients Age > 18 years Patients requiring oxygen at least> 5L/min up to 15 L/min (by FM/ NRM)to maintain saturation >92% to 96%  NOTE: Clinically suspected COVID-19 = fever (Temperature >37.8 Degree Celsius) + respiratory symptoms + Radiological evidences Exclusion criteria  Multi-organ failure Severe ARDS (requiring HFNC orventilatory support on presentation in the form ofinvasive or non-invasive ventilation) Septic Shock Severe liver disease Acute Heart Failure Acute Kidney Injury (where GFR< 15 and plasma-sulfamethoxazoleconcentration cannot be monitored) Drug allergy/intolerance to co-trimoxazole / Sulphar sensitivity Pregnancy