Post-exposure Prophylaxis or Preemptive Therapy for SARSCoronavirus-2: A Pragmatic Randomized Clinical Trial (COVID-19 PEP RCT)

This trial, conducted in Canada and the USA, assessed the effect of Hydroxychloroquine as a post exposure prophylaxis or a treatment for patients with mild COVID-19 infections.


Primary objectives:  

  • Test if hydroxychloroquine can prevent development of COVID-19 disease after known exposure to the SARS-CoV2 virus. 
  • Test if early preemptive therapy in non-hospitalized adults with symptomatic COVID-19 disease can prevent disease progression and hospitalization


Type of studyInterventionalRCT, Phase 3  


Treatment testedHydroxychloroquine


Countries: Canada, USA


Sample size3000 


Study participants:  

  • Adult Household contacts or Healthcare workers exposed to persons with COVID-19 disease within 4 days, or 
  • Non-hospitalized adults with symptomatic COVID-19 disease within 4 days of onset  


Study status Completed


Study documents


Principal investigator

  • David Boulware, MD, MPH, University of Minnesota


More information




Last modified: September 2020


Note that study-related documents posted on the COVID-19 Clinical Research Coalition (COVID-19 CRC) website have been shared by coalition members for information. Some may have been approved by Ethics Review Boards and others may still be in draft form. Documents posted here may have been further amended before being used in the conduct of the respective trials they were designed for. It is recommended that users review these documents carefully and, if they plan to use them, adapt them appropriately for their intended use. The COVID-19 CRC and its members cannot accept any liability for any claim, loss or damages as a result of any reliance placed on, or use of, these documents.