Inclusion Criteria:  1) aged between 1-month to 18-year old (boy or girl), 2) definitive or clinical diagnosis of severe acute respiratory syndrome (SARS)-like coronavirus 2 (SARS-COV-2) infection (by either a positive SARS-COV-2 polymerase chain reaction (PCR) test or a suggestive computed tomography (CT) scan, 3) no history or evidence of cancer or renal, hepatic, endocrine or viral disorders (including HIV/AIDS), 4) no history of supplementation either with vitamin A (VA) or with a multivitamin containing VA within the last 4 months, and 5) not participated in other clinical trials.  Exclusion Criteria:  1) mildly infected with SARS-COV-2 virus, and 2) pregnancy or lactation.