Randomized clinical trial of nitazoxanide or sofosbuvir/daclatasvir for the prevention of SARS-CoV-2 infection

J Antimicrob Chemother. 2022 Sep 30;77(10):2706-2712. doi: 10.1093/jac/dkac266.


Background: The COVER trial evaluated whether nitazoxanide or sofosbuvir/daclatasvir could lower the risk of SARS-CoV-2 infection. Nitazoxanide was selected given its favourable pharmacokinetics and in vitro antiviral effects against SARS-CoV-2. Sofosbuvir/daclatasvir had shown favourable results in early clinical trials.

Methods: In this clinical trial in Johannesburg, South Africa, healthcare workers and others at high risk of infection were randomized to 24 weeks of either nitazoxanide or sofosbuvir/daclatasvir as prevention, or standard prevention advice only. Participants were evaluated every 4 weeks for COVID-19 symptoms and had antibody and PCR testing. The primary endpoint was positive SARS-CoV-2 PCR and/or serology ≥7 days after randomization, regardless of symptoms. A Poisson regression model was used to estimate the incidence rate ratios of confirmed SARS-CoV-2 between each experimental arm and control.

Results: Between December 2020 and January 2022, 828 participants were enrolled. COVID-19 infections were confirmed in 100 participants on nitazoxanide (2234 per 1000 person-years; 95% CI 1837-2718), 87 on sofosbuvir/daclatasvir (2125 per 1000 person-years; 95% CI 1722-2622) and 111 in the control arm (1849 per 1000 person-years; 95% CI 1535-2227). There were no significant differences in the primary endpoint between the treatment arms, and the results met the criteria for futility. In the safety analysis, the frequency of grade 3 or 4 adverse events was low and similar across arms.

Conclusions: In this randomized trial, nitazoxanide and sofosbuvir/daclatasvir had no significant preventative effect on infection with SARS-CoV-2 among healthcare workers and others at high risk of infection.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Antiviral Agents / therapeutic use
  • COVID-19* / prevention & control
  • Carbamates
  • Humans
  • Imidazoles
  • Nitro Compounds
  • Pyrrolidines
  • SARS-CoV-2
  • Sofosbuvir / therapeutic use
  • South Africa
  • Thiazoles
  • Treatment Outcome
  • Valine / analogs & derivatives


  • Antiviral Agents
  • Carbamates
  • Imidazoles
  • Nitro Compounds
  • Pyrrolidines
  • Thiazoles
  • Valine
  • daclatasvir
  • nitazoxanide
  • Sofosbuvir

Grant support