Study aim: Comparison of the therapeutic effect of Favipiravir with Standard medication in COVID-19 patients with moderate-severity referred to the infectious disease clinic of Labbafinejad hospital in 1400 Design: Phase 3 block randomized, open-lable clinical trial with intervention and control groups (allocation ratio 1:1) The sample size of each group is considered about 40 . Settings and conduct: This study was performed on patients with moderate COVID-19 referred to the infectious diseases clinic of Labbafinejad hospital in 2021. Eligible patients, they are divided into two groups of intervention and control using a random number table. The intervention group, in addition to supportive and symptomatic treatment, receives oral Favipiravir (according to the order mentioned above). The control group recieves standard medication. A trained clinical evaluator then reports patients' recovery on days 1 (start of treatment), 3, 5, and 7. Blood tests are also taken from the patient on days 1 and 7. This is an open-lable study. Participants/Inclusion and exclusion criteria: Inclusion criteria are: Laboratory confirmation of COVID-19 virus by RT-PCR or COVID-19 compliant imaging evidence; Moderate-severity disease (respiration rate <30 per minute, oxygen saturation> 94%, or pulmonary infiltration <50% in both lungs); and Age over 14 years. Exclusion criteria are: Immunocomprimised patients; Consumption of effective drugs in the treatment of COVID-19; and History anaphylaxis. Intervention groups: The intervention group, in addition to supportive and symptomatic treatment, receives oral Favipiravir at a dose of 1600 mg every 12 hours for the first day and then 600 mg every 12 hours for the next four days. The control group also receives standard medication. Main outcome variables: Trend of clinical symptoms