Study aim: Evaluation of the efficacy of Molnopiravir in recovery pace of patients with mild COVID-19 Design: Phase 2 and 3 double-blind clinical trials with parallel groups that will be randomized using quadruple blocks and will be performed on 500 patients in two intervention groups with Molnupiravir and placebo groups Settings and conduct: This research project will be performed in patients with COVID-19 in the initial phase who have referred to the Infectious Diseases Clinic of Baqiyatallah Hospital in Tehran. The study will be double-blinded and patients and outcome assessors will be blinded to the intervention groups. Drugs and placebo will be exactly the same, and drug labels will remain unknown to researchers until the end of the study. Participants/Inclusion and exclusion criteria: Inclusion criteria: having a patient in the family; Positive COVID-19 PCR test; Onset of clinical symptoms of the patient less than 3 days; Willing and able to take oral medication; Blood oxygen level above 93%. Exclusion criteria: pregnancy; Breastfeeding; any underlying diseases; history of allergy to antiviral drugs; thrombocytopenia; receiving recent vaccination of COVID-19 Intervention groups: Intervention group: Molnopiravir 200 mg daily for up to five days with diphenhydramine syrup / vitamin C tablets / vitamin D tablets / famotidine tablets 40 mg every 12 hours and naproxen in case of muscle pain and fever. Control group: similar intervention with the difference that they will receive placebo instead of molnopiravir. Main outcome variables: PCR test and CT number; Fever; dyspnea; Cough; respiratory rate; Serum ESR; Serum CRP; pulse rate; blood pressure; Dry cough