Favipiravir for the treatment of patients with COVID-19: a systematic review and meta-analysis

BMC Infect Dis. 2021 May 27;21(1):489. doi: 10.1186/s12879-021-06164-x.


Background: Favipiravir possesses high utility for treating patients with COVID-19. However, research examining the efficacy and safety of favipiravir for patients with COVID-19 is limited.

Methods: We conducted a systematic review of published studies reporting the efficacy of favipiravir against COVID-19. Two investigators independently searched PubMed, the Cochrane Database of Systematic Reviews, MedRxiv, and ClinicalTrials.gov (inception to September 2020) to identify eligible studies. A meta-analysis was performed to measure viral clearance and clinical improvement as the primary outcomes.

Results: Among 11 eligible studies, 5 included a comparator group. Comparing to the comparator group, the favipiravir group exhibited significantly better viral clearance on day 7 after the initiation of treatment (odds ratio [OR] = 2.49, 95% confidence interval [CI] = 1.19-5.22), whereas no difference was noted on day 14 (OR = 2.19, 95% CI = 0.69-6.95). Although clinical improvement was significantly better in the favipiravir group on both days 7 and 14, the improvement was better on day 14 (OR = 3.03, 95% CI = 1.17-7.80) than on day 7 (OR = 1.60, 95% CI = 1.03-2.49). The estimated proportions of patients with viral clearance in the favipiravir arm on days 7 and 14 were 65.42 and 88.9%, respectively, versus 43.42 and 78.79%, respectively, in the comparator group. The estimated proportions of patients with clinical improvement on days 7 and 14 in the favipiravir group were 54.33 and 84.63%, respectively, compared with 34.40 and 65.77%, respectively, in the comparator group.

Conclusions: Favipiravir induces viral clearance by 7 days and contributes to clinical improvement within 14 days. The results indicated that favipiravir has strong possibility for treating COVID-19, especially in patients with mild-to-moderate illness. Additional well-designed studies, including examinations of the dose and duration of treatment, are crucial for reaching definitive conclusions.

Keywords: COVID-19; Clinical improvement; Favipiravir; SARS-CoV-2; Viral clearance.

Publication types

  • Meta-Analysis
  • Systematic Review

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Amides / adverse effects
  • Amides / therapeutic use*
  • Antiviral Agents / adverse effects
  • Antiviral Agents / therapeutic use*
  • COVID-19 Drug Treatment*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Pyrazines / adverse effects
  • Pyrazines / therapeutic use*
  • SARS-CoV-2
  • Treatment Outcome
  • Viral Load / drug effects
  • Young Adult


  • Amides
  • Antiviral Agents
  • Pyrazines
  • favipiravir