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HCQ for Primary Prophylaxis Against COVID19 in Health-care Workers

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details. Identifier: NCT04336748
Recruitment Status : Not yet recruiting
First Posted : April 7, 2020
Last Update Posted : April 7, 2020
Information provided by (Responsible Party):
Matthias Vossen, Medical University of Vienna

Tracking Information
First Submitted Date  ICMJE April 4, 2020
First Posted Date  ICMJE April 7, 2020
Last Update Posted Date April 7, 2020
Estimated Study Start Date  ICMJE April 2020
Estimated Primary Completion Date July 2020   (Final data collection date for primary outcome measure)
Current Primary Outcome Measures  ICMJE
 (submitted: April 4, 2020)
Symptomatic or asymptomatic SARS-CoV-2 infection confirmed by PCR [ Time Frame: 4 weeks ]
Original Primary Outcome Measures  ICMJE Same as current
Change History No Changes Posted
Current Secondary Outcome Measures  ICMJE
 (submitted: April 4, 2020)
  • Viral load during SARS-CoV-2 infection [ Time Frame: 4 weeks ]
  • Seroconversion during the study period [ Time Frame: 4 weeks ]
  • Incidence of any acute respiratory infection [ Time Frame: 4 weeks ]
  • Days of sick leave [ Time Frame: 4 weeks ]
Original Secondary Outcome Measures  ICMJE Same as current
Current Other Pre-specified Outcome Measures Not Provided
Original Other Pre-specified Outcome Measures Not Provided
Descriptive Information
Brief Title  ICMJE HCQ for Primary Prophylaxis Against COVID19 in Health-care Workers
Official Title  ICMJE Low-dose Hydroxychloroquine for Primary Prophylaxis Against SARS-CoV-2 in Health-care Workers - a Randomized, Double-blind, Controlled Trial
Brief Summary


Aim: To demonstrate the efficacy of low-dose hydroxychloroquine as primary prevention in healthcare workers Design, participants and interventions: Prospective, randomized, parallel group, double-blinded, placebo controlled, study.

including 440 participants who will be randomised to 2 treatment arms: hydroxychloroquine or placebo.

Outcome variables: symptomatic or asymptomatic SARS-CoV-2 infection confirmed by PCR, viral load during SARS-CoV-2 infection, seroconversion during the study period, incidence of any acute respiratory infection, days of sick leave.

Statistical considerations: No trials have been published investigating the efficacy of HCQ as primary prophylaxis of SARS-CoV-2 infection in health care workers. Thus, sample size calculations in the proposed trial are based on the investigators' best estimates for several parameters.

In accordance to the effect of oseltamivir against symptomatic influenza, we assumed an approximate effectiveness of approximately 60% (HR of 0.4) ( as realistic. As a prophylactic intervention with HCQ, which may have side effects and for which supply shortage can be expected, was judged justifiable only if its effectiveness is high, we based our sample size consideration on a HR of 0.3. To estimate the probability of an event in both the experimental and the control group, very little data is available. In a Dutch point-prevalence study 0-10% of health-care workers were infected depending on the healthcare institution, depending on the hospital. This point-prevalence study was performed between 6 and 9 March, when the reported number of cases in the Netherlands was 33 and 77, respectively, according to the RIVM ( Additionally, in an a report published in the Lancet, 20% of responding healthcare workers in Italy were found to be infected with SARS-CoV2 within less than one month ( Several media reports indicate that this proportion is similar across various healthcare institutions and countries ( and (

As the proposed study will be performed in a high-risk setting, we assumed an event (i.e. PCR positivity) probability of 10% in the control group and 3% in the experimental arm after the maximum study period. In summary, a sample size of 210 participants per arm is necessary to detect a HR of 0.3 with a power of 80.3% with an alpha-error of 0.05. To account for drop-outs and asymptomatic, undetected infection at inclusion or past infection with existing immunity, an additional 10 participants will randomized per treatment arm. The overall study population is therefore 440 participants.

Statistical analysis will be based on two populations: A Modified Intention to Treat population excluding those who withdrew consent after randomization and those with a positive serology at baseline. And a per protocol population including all randomized subjects who completed at least 3 out of 4 follow-up visits and took at least 80% of all doses of study medication.

Detailed Description Not Provided
Study Type  ICMJE Interventional
Study Phase  ICMJE Phase 3
Study Design  ICMJE Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Investigator)
Primary Purpose: Prevention
Condition  ICMJE
  • Sars-CoV2
  • Infection Viral
  • Healthcare Worker
  • Prophylaxis
Intervention  ICMJE Drug: Hydroxychloroquine
low dose (200mg) Hydroxychloroquine once daily for 4 weeks
Study Arms  ICMJE
  • Active Comparator: Hydroxychloroquine
    200mg once daily
    Intervention: Drug: Hydroxychloroquine
  • Placebo Comparator: Placebo
    Intervention: Drug: Hydroxychloroquine
Publications * Not Provided

*   Includes publications given by the data provider as well as publications identified by Identifier (NCT Number) in Medline.
Recruitment Information
Recruitment Status  ICMJE Not yet recruiting
Estimated Enrollment  ICMJE
 (submitted: April 4, 2020)
Original Estimated Enrollment  ICMJE Same as current
Estimated Study Completion Date  ICMJE August 2020
Estimated Primary Completion Date July 2020   (Final data collection date for primary outcome measure)
Eligibility Criteria  ICMJE

Inclusion Criteria:

  • Health-care worker with frequent contact with confirmed COVID-19 patients
  • No active or past infection with SARS-CoV-2
  • 18 years of age or older
  • No allergy or contraindication to hydroxychloroquine
  • written informed consent

Exclusion Criteria:

  • Age of less than 18 years
  • Pregnancy or lactation
  • unwillingness to use effective contraception during the participation in the trial
  • Use of concomitant medication that prolongs the QT interval
  • Allergy or contraindication to hydroxychloroquine
  • Retinopathy or maculopathy
  • Neuromuscular diseases (i.e Myasthenia gravis, Parkinson's disease)
  • G6PD Deficiency
Sex/Gender  ICMJE
Sexes Eligible for Study: All
Ages  ICMJE 18 Years and older   (Adult, Older Adult)
Accepts Healthy Volunteers  ICMJE Yes
Contacts  ICMJE
Listed Location Countries  ICMJE Not Provided
Removed Location Countries  
Administrative Information
NCT Number  ICMJE NCT04336748
Other Study ID Numbers  ICMJE HCQ prophylaxis for COVID19
Has Data Monitoring Committee Not Provided
U.S. FDA-regulated Product
Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
IPD Sharing Statement  ICMJE Not Provided
Responsible Party Matthias Vossen, Medical University of Vienna
Study Sponsor  ICMJE Medical University of Vienna
Collaborators  ICMJE Not Provided
Investigators  ICMJE Not Provided
PRS Account Medical University of Vienna
Verification Date April 2020

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP