A systematic review of trial registry entries for randomized clinical trials investigating COVID-19 medical prevention and treatment

PLoS One. 2020 Aug 20;15(8):e0237903. doi: 10.1371/journal.pone.0237903. eCollection 2020.


Aim: To identify investigated interventions for COVID-19 prevention or treatment via trial registry entries on planned or ongoing randomised clinical trials. To assess these registry entries for recruitment status, planned trial size, blinding and reporting of mortality.

Methods: We identified trial registry entries systematically via the WHO International Clinical Trials Registry Platform and 33 trial registries up to June 23, 2020. We included relevant trial registry entries for randomized clinical trials investigating medical preventive, adjunct or supportive therapies and therapeutics for treatment of COVID-19. Studies with non-random and single-arm design were excluded. Trial registry entries were screened by two authors independently and data were systematically extracted.

Results: We included 1303 trial registry entries from 71 countries investigating 381 different single interventions. Blinding was planned in 47% of trials. Sample size was >200 participants in 40% of trials and a total of 611,364 participants were planned for inclusion. Mortality was listed as an outcome in 57% of trials. Recruitment was ongoing in 54% of trials and completed in 8%. Thirty-five percent were multicenter trials. The five most frequent investigational categories were immune modulating drugs (266 trials (20%)), unconventional medicine (167 trials (13%)), antimalarial drugs (118 trials (9%)), antiviral drugs (100 trials (8%)) and respiratory adjuncts (78 trials (6%)). The five most frequently tested uni-modal interventions were: chloroquine/hydroxychloroquine (113 trials with 199,841 participants); convalescent plasma (64 trials with 11,840 participants); stem cells (51 trials with 3,370 participants); tocilizumab (19 trials with 4,139 participants) and favipiravir (19 trials with 3,210 participants).

Conclusion: An extraordinary number of randomized clinical trials investigating COVID-19 management have been initiated with a multitude of medical preventive, adjunctive and treatment modalities. Blinding will be used in only 47% of trials, which may have influence on future reported treatment effects. Fifty-seven percent of all trials will assess mortality as an outcome facilitating future meta-analyses.

Publication types

  • Systematic Review

MeSH terms

  • Anti-Bacterial Agents / therapeutic use
  • Anti-Inflammatory Agents / therapeutic use
  • Antibodies, Monoclonal, Humanized / therapeutic use
  • Antimalarials / therapeutic use
  • Antiviral Agents / therapeutic use
  • Betacoronavirus*
  • COVID-19
  • COVID-19 Drug Treatment
  • Coronavirus Infections / drug therapy*
  • Coronavirus Infections / mortality
  • Coronavirus Infections / prevention & control*
  • Coronavirus Infections / virology
  • Drug Therapy, Combination
  • Humans
  • Hydroxychloroquine / therapeutic use
  • Interleukin-6 / antagonists & inhibitors
  • Pandemics / prevention & control*
  • Pneumonia, Viral / drug therapy*
  • Pneumonia, Viral / mortality
  • Pneumonia, Viral / prevention & control*
  • Pneumonia, Viral / virology
  • Randomized Controlled Trials as Topic*
  • Registries*
  • SARS-CoV-2
  • Treatment Outcome


  • Anti-Bacterial Agents
  • Anti-Inflammatory Agents
  • Antibodies, Monoclonal, Humanized
  • Antimalarials
  • Antiviral Agents
  • IL6 protein, human
  • Interleukin-6
  • Hydroxychloroquine

Grants and funding

The authors received no specific funding for this work.