Favipiravir, previously known as T-705, is a prodrug of a purine nucleotide, favipiravir ribofuranosyl-5'-triphosphate. The active agent inhibits the RNA polymerase, halting viral replication. Most of favipiravir's preclinical data are derived from its influenza and Ebola activity; however, the agent also demonstrated broad activity against other RNA viruses. In vitro, the 50% effective concentration (EC50) of favipiravir against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was 61.88 μM/L in Vero E6 cells.

Limited clinical experience has been reported supporting the use of favipiravir for COVID-19. In a prospective, randomized, multicenter study, favipiravir (n = 120) was compared with Arbidol (n = 120) for the treatment of moderate and severe COVID-19 infections. Differences in clinical recovery at day 7 were observed in patients with moderate infections (71.4% favipiravir and 55.9% Arbidol, P = .019). No significant differences were observed in the severe or severe and moderate (combined) arms.73 These data support further investigation with randomized clinical trials (RCTs) of the efficacy of favipiravir for the treatment of COVID-19.

Chloroquine has been a broadly-utilized anti-malaria agent which back in 2006, had been proved to be a powerful wide-spectrum antiviral. Moreover, Chloroquine has the characteristics of anti-inflammatory and immune-modulatory by inhibiting the production of tumor necrosis factor alpha (TNF-α) along with interleukin 6 (IL-6). In the first half of February, a study illustrated puissant inhibition of SARS-CoV-2 by Chloroquine, when taking two 500-mg tablets of it by mouth per day; similar to some clinical studies in China through this outbreak. According to the news briefing of a study, it was indicated that chloroquine phosphate actually outdo the control treatment in inhibition of pneumonia exacerbation, improving lung imaging findings, and curtailing the disease course. Another study evaluated the possible doses of chloroquine (CQ) and hydroxychloroquine (HCQ) to find the optimized dose in treatment of COVID-19. They revealed that while within in-vitro settings Hydroxychloroquine is more potent than chloroquine. As a conclusion, they suggested a 800 mg daily dose of hydroxychloroquine, followed by an overall maintenance dose of 400 mg per day divided in two separate doses, which was three-fold more potent compared to the 500 mg twice daily administration of chloroquine in 5 days. The new study published in 16th March, pointed out that hydroxychloroquine was notably effectual in eradicating SARS-CoV-2 from the nasopharynx. Currently the evidence is quite inconclusive about the effectiveness or comparative effectiveness of either HCQ or CQ. Moreover, CQ has recently become scarce and even unavailable for ordering due to a huge demand for it, all because of a significant interest gained as a potential medicinal alternative for the management of COVID-19. In spite of all, the primary experience in China and France is propitious for the potential role of chloroquine, or alternatively hydroxychloroquine, for managing COVID-19.

The present study is a randomized, double-blind, controlled, clinical trial, with the approval of the ethics committee will be conducted on patients who have a positive test confirming COVID-19 in Shahid Modarres Medical Education Center and Hospital in Tehran. Patients will be randomly assigned to the two arms of the study and after completing the course of treatment and collecting and analyzing the necessary information from each patient, the results of the study will be published both on this site and in the form of an article in a reputable international journal.