Systematic review of registered trials of Hydroxychloroquine prophylaxis for COVID-19 healthcare workers at the first third of 2020

In the absence of a vaccine the medical and scientific community is looking intensely at utilizing a pre or post exposure drug that could decrease viremia. The search for a medication that could reduce risk of serious disease, and ideally of any manifestation of disease from SARS-CoV2, and of asymptomatic shedding of SARS-CoV2 is of urgent interest. Repurposing existing pharmaceuticals is among the approaches to achieve these ends. We performed a systematic review of all interventional studies registered in ClinicalTrials.gov with a focus on one repurposed drug, Hydroxychloroquine (HCQ). The detailed analysis of these studies, some of them already recruiting, provide an overall picture of HCQ use as a COVID-19 prophylaxis around the world. Among the included studies, all but three were randomized and parallel and most of them (74%, 23/31) were double-blinded to quadruple-blinded studies. We found a great diversity in dosing and nearly all the possible scientifically reasonable regimens are under evaluation. This diversity offers benefits as well as challenges. Importantly, the final analysis of these trials should be done through an extensive reading of the results in regard to the clinical design, it will be crucial to carefully read and evaluate the results of each study in regards to the clinical design rather than quickly glancing a 140 characters-based social media message announcing the failure or success of a drug against a disease.