Abstract: Clinical Microbiology and Infection 27 (2021) 611e617 Contents lists available at ScienceDirect Clinical Microbiology and Infection journal homepage: www.clinicalmicrobiologyandinfection.com Original article Effect of hydroxychloroquine pre-exposure on infection with SARSCoV-2 in rheumatic disease patients: a population-based cohort study Sun-Young Jung 1, 2, Myo-Song Kim 1, 2, Min-Chul Kim 3, Seong-Ho Choi 3, *, Jin-Won Chung 3, Sang Tae Choi 4, ** 1) College of Pharmacy, Chung-Ang University, Seoul, Republic of Korea Department of Global Innovative Drugs, Graduate School of Chung-Ang University, Seoul, Republic of Korea Division of Infectious Diseases, Department of Internal Medicine, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea 4) Division of Rheumatology, Department of Internal Medicine, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Republic of Korea 2) 3) a r t i c l e i n f o a b s t r a c t Article history: Received 25 September 2020 Received in revised form 29 November 2020 Accepted 5 December 2020 Available online 11 December 2020 Objectives: Early in vitro studies have suggested that hydroxychloroquine (HCQ) is a potentially useful drug against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. This study was conducted to determine whether HCQ had a preventive effect on coronavirus disease 2019 (COVID-19) in rheumatic disease patients who were taking HCQ. Methods: We conducted a population-based retrospective cohort study using the records of the Korean Health Insurance Review and Assessment (HIRA) claim records. The clinical data of patients with rheumatoid arthritis (RA) or systemic lupus erythematosus (SLE) who were tested for SARS-CoV-2 were investigated. We compared the attack rate of COVID-19 between those who underwent HCQ therapy within 14 days before the test for SARS-CoV-2 (HCQ users) and HCQ non-users. Data were analysed using logistic regression models, c2, and Student's t-tests. Results: As of 15th May 2020, 2066 patients with RA or SLE were tested for COVID-19. Among them, 31.4% (649/2066) were treated with HCQ. Most HCQ users (93.7%, 608/649) were taking 200e400 mg/ day recommended for the treatment of rheumatic diseases. The attack rate of COVID-19 in the HCQ users (2.3%, 15/649) did not differ from that in the HCQ non-users (2.2%, 31/1417) (p 0.86). Conclusions: HCQ prophylactic use at a usual dose did not prevent COVID-19 in patients with rheumatic disease. Sun-Young Jung, Clin Microbiol Infect 2021;27:611 © 2020 The Authors. Published by Elsevier Ltd on behalf of European Society of Clinical Microbiology and Infectious Diseases. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/). Editor: L. Scudeller Keywords: COVID-19 Hydroxychloroquine Pre-exposure prophylaxis Rheumatic diseases Severe acute respiratory syndrome coronavirus 2