Abstract: life Article Hospital-Based Quasi-Experimental Study on Hydroxychloroquine Pre-Exposure Prophylaxis for COVID-19 in Healthcare Providers with Its Potential Side-Effects Lubaba Shahrin 1,2, * , Mustafa Mahfuz 2 , Md. Waliur Rahman 2 , Md. Rezaul Hossain 3 , Afsana Mim Khandaker 4 , Md. Ashraful Alam 2 , Din M. M. F. Osmany 5 , Md. Munirul Islam 2 , Mohammod Jobayer Chisti 1,2 , Chaudhury Meshkat Ahmed 5 and Tahmeed Ahmed 2 1 2 3 4 5 * Citation: Shahrin, L.; Mahfuz, M.; Rahman, M.W.; Hossain, M.R.; Khandaker, A.M.; Alam, M.A.; Osmany, D.M.M.F.; Islam, M.M.; Chisti, M.J.; Ahmed, C.M.; et al. Hospital-Based Quasi-Experimental Study on Hydroxychloroquine Pre-Exposure Prophylaxis for COVID-19 in Healthcare Providers with Its Potential Side-Effects. Life 2022, 12, 2047. https://doi.org/ 10.3390/life12122047 Academic Editor: Simona Zaami Received: 22 October 2022 Accepted: 30 November 2022 Published: 7 December 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in Dhaka Hospital, International Centre for Diarrheal Disease Research, Bangladesh (icddr, b), Dhaka 1212, Bangladesh Nutrition and Clinical Services Division, International Centre for Diarrheal Disease Research, Bangladesh (icddr, b), Dhaka 1212, Bangladesh Department of Epidemiology, University of Washington, Seattle, WA 98195, USA Department of Nutrition, University of Nevada, Reno, NV 89557, USA Department of Cardiology, Bangabandhu Sheikh Mujib Medical University, Dhaka 1000, Bangladesh Correspondence: lubabashahrin@icddrb.org; Tel.: +880-2-8860523-32 (ext. 2303); Fax: +880-2-882-3116 or +880-2-988-5657 Abstract: Considering that it has been more than 24 months since SARS-CoV-2 emerged, it is crucial to identify measures that prevent and control pathogen transmission in workplace settings. Our aim was to report results of a hospital-based program that delivered hydroxychloroquine (HCQ) tablets as COVID-19 prophylaxis to the frontline healthcare workers (HCW)s who cared for COVID-19 patients and to evaluate the efficacy of HCQ. Setting and participants: Quasi-experimental, controlled, single-center study. The included participants were doctors, nurses, health workers, cleaning staff, and non-healthcare supportive staff. The main outcome was contracting COVID-19 anytime during the period of taking the prophylaxis, confirmed by RT-PCR. A total of 336 participants, without any clinical evidence of COVID-19 and without any known contact with family members, were included in the trial; 230 were assigned to HCQ and 106 declined to take any drug. Results: Among the participants, 43 (18.7%) in the HCQ group and 11 (10.4%) participants in the control group developed COVID-19. For the evaluation of side effects, we evaluated 12-lead ECGs of both groups at the baseline and after 4 weeks to monitor QTc interval. A total of 91% (198 of 217) participants in the prophylaxis group and 92% (11 of 12) in the control group had a QTc < 45o msec, which is within normal limits. Conclusions: Although the number of symptomatic infections in health personnel was lower in the control group, the difference was not statistically significant. However, in the absence of any effective pre-exposure prophylaxis medicine for COVID-19, practicing proper infection prevention and control (IPC) and vaccination is the only way forward. Keywords: hydroxychloroquine; COVID-19; preexposure prophylaxis; corrected QT interval; healthcare workers published maps and institutional..