Abstract: Original Article Hydroxychloroquine pre‑exposure prophylaxis for COVID‑19 among healthcare workers: Initial experience from India Harshith B. Kadnur1, Anivita Aggarwal1, Manish Soneja1, Komal Singh1, Ankit Mittal1, Neeraj Nischal1, Praveen Tirlangi1, Adil Rashid Khan1, Devashish Desai1, Ankesh Gupta1, Arvind Kumar1, Pankaj Jorwal1, Ashutosh Biswas1, Ravindra Mohan Pandey2, Naveet Wig1, Randeep Guleria3 Departments of 1Medicine, 2Biostatistics and 3Pulmonary Medicine and Sleep Disorder, All India Institute of Medical Sciences, New Delhi, India A bstract Background: Hydroxychloroquine (HCQ) had generated considerable interest for coronavirus disease 2019 (COVID‑19) prophylaxis. We conducted a prospective observational study at a tertiary care hospital in India, with dedicated COVID‑19 care facilities. Objectives: Primary objective was incidence of adverse effects, secondary objective being efficacy in preventing COVID‑19. Methods: Healthcare workers were recruited and grouped based on voluntary HCQ prophylaxis as per national guidelines. Side effects in HCQ group were graded in accordance with national cancer institute-common terminology criteria for adverse events (NCI‑CTCAE) version 5.0. At 3–7‑week follow‑up, groups were compared for COVID‑19 exposure, symptoms development and severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) RT‑PCR results. Results: Among 358 participants recruited, 216 (60.3%) were males and mean age was 31.2 ± 6.6 years. Chemoprophylaxis was initiated by 258 (72%) participants. After loading dose, 7 (2.7%) reported grade 2 and 1 (0.4%) grade 3 adverse effects. Discontinuation of HCQ due to side effects was reported in 11 (4.3%) participants. Electrocardiogram was done by 50 (19.4%) participants on HCQ; no abnormalities were noted. A total of 106 (41%) among those taking and 63 (63%) among those not taking HCQ were tested for SARS‑CoV‑2 due to influenza‑like illness or significant exposure. Among all participants, 25 (6.9%, 95% confidence interval [CI] 4.3–9.6) developed COVID‑19 during the study period. In the group taking HCQ, 10 (3.9%) tested positive compared to 15 (15%) in the group not taking HCQ (P < 0.001). Odds ratio with HCQ intake was 0.34 (95% CI 0.13–0.83, P = 0.01) and the number needed to treat was 12. Conclusion: HCQ is safe at the recommended dose for pre‑exposure prophylaxis of COVID‑19. Keywords: COVID‑19, healthcare workers, hydroxychloroquine, pre‑exposure prophylaxis, SARS‑CoV‑2