Hydroxychloroquine for COVID-19 Post-exposure Prophylaxis (PEP)

This is a randomized, multi-center, placebo-equivalent (ascorbic acid) controlled, blinded study of Hydroxychloroquine (HCQ) post-exposure prophylaxis (PEP) for the prevention of SARS-CoV-2 infection in adults exposed to the virus.The overarching goal of this study is to assess the effectiveness of HCQ PEP on the incidence of SARS-CoV-2 detection by polymerase chain reaction (PCR) to inform public health control strategies.This study will enroll up to 2000 asymptomatic men and women 18 to 80 years of age (inclusive) at baseline who are close contacts of persons with PCR-confirmed SARS-CoV-2 or clinically suspected COVID-19 and a pending SARS-CoV-2 PCR test. Eligible participants will be enrolled and randomized 1:1 to HCQ or ascorbic acid at the level of the household (all eligible participants in one household will receive the same intervention). Participants will be counseled about the preliminary in vitro data on HCQ activity against SARS CoV-2 and equipoise regarding efficacy in humans.The duration of study participation will be approximately 28 days.