* covid-19 critically ill patients (news-2 score \<7), * unable to take oral medication, * immunocompromised, * creatinine clearance (ccl) \< 30 ml/min, * aspartate transaminase (ast) or alanine transaminase (alt) \> 5 times upper limit of normal (uln), * d-dimer \> 2microgram per liter, or * known comorbid condition like hypertension, cardiovascular disease, diabetes mellites, asthma, copd, cerebrovascular disorder, malignancy of any type, pregnancy, * bmi less than 18 * smoking history (one pack per day) for past six months

* covid-19 critically ill patients (news-2 score \<7), * unable to take oral medication, * immunocompromised, * creatinine clearance (ccl) \< 30 ml/min, * aspartate transaminase (ast) or alanine transaminase (alt) \> 5 times upper limit of normal (uln), * d-dimer \> 2microgram per liter, or * known comorbid condition like hypertension, cardiovascular disease, diabetes mellites, asthma, copd, cerebrovascular disorder, malignancy of any type, pregnancy, * bmi less than 18 * smoking history (one pack per day) for past six months

- covid-19 critically ill patients (news-2 score <7), - unable to take oral medication, - immunocompromised, - creatinine clearance (ccl) < 30 ml/min, - aspartate transaminase (ast) or alanine transaminase (alt) > 5 times upper limit of normal (uln), - d-dimer > 2microgram per liter, or - known comorbid condition like hypertension, cardiovascular disease, diabetes mellites, asthma, copd, cerebrovascular disorder, malignancy of any type, pregnancy, - bmi less than 18 - smoking history (one pack per day) for past six months

- covid-19 critically ill patients (news-2 score <7), - unable to take oral medication, - immunocompromised, - creatinine clearance (ccl) < 30 ml/min, - aspartate transaminase (ast) or alanine transaminase (alt) > 5 times upper limit of normal (uln), - d-dimer > 2microgram per liter, or - known comorbid condition like hypertension, cardiovascular disease, diabetes mellites, asthma, copd, cerebrovascular disorder, malignancy of any type, pregnancy, - bmi less than 18 - smoking history (one pack per day) for past six months