The efficacy and adverse effects of favipiravir on patients with COVID-19: A systematic review and meta-analysis of published clinical trials and observational studies

•The use of favipiravir shortened the viral clearance and clinical improvement time.•The use of favipiravir significantly reduced damages on radiology images when recovered.•The use of favipiravir significantly increased the rate of hyperuricemia. This study aimed to evaluate the efficacy and adverse events of favipiravir in patients with COVID-19. Our protocol was registered on PROSPERO (CRD42020206305). Fourteen databases were searched until February 8th, 2021. An update search for new RCTs was done on March 2nd, 2022. Meta-analysis was done for randomized controlled trials (RCTs) and non-RCTs. Overall, 157 studies (24 RCTs, 1 non-RCT, 21 observational studies, 2 case series, and 106 case reports) were included. On hospitalized patients, in comparison to standard of care, favipiravir showed a higher rate of viral clearance at day 5 (RR = 1.60, p = 0.02), defervescence at day 3–4 (RR = 1.99, p