Published: 2020-12-28

Pre-exposure hydroxychloroquine prophylaxis for COVID-19 in healthcare workers: a retrospective cohort

Raja Bhattacharya, Sampurna Chowdhury, Anita Nandi, Rishav Mukherjee, Manish Kulshrestha, Rohini Ghosh, Souvik Saha


Background: While several trials are ongoing for treatment of Corona virus 2019 (COVID-19), scientific research on chemoprophylaxis is still lacking even though it has potential to flatten the curve allowing us time to complete research on vaccines.

Methods: This retrospective cohort study explores the potential of hydroxychloroquine (HCQ) as a pre- exposure prophylaxis for COVID-19 among 106 health care workers (HCW) exposed to COVID-19 patients, at a tertiary care hospital in India where there was an abrupt cluster outbreak within on duty personnel. HCWs who had voluntarily taken HCQ prior to exposure were considered one cohort while those who had not were considered to be the Control group. All participants with a verifiable high-risk contact history were tested for COVID-19 by RT- PCR.

Results: The two cohorts were comparable in terms of age, gender, co-morbidity and exposure. The primary outcome was incidence rates of RT-PCR positive COVID-19 infection among HCQ users and Controls.106 HCW were examined of whom 54 were HCQ users. The comparative analysis of incidence of infection between the two groups demonstrated that voluntary HCQ usage was associated with lesser likelihood of developing severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection (4 out of 54 HCW), compared to those who were not on it (20 out of 52 HCW), χ2=14.59, p<0.001. None of the HCQ users noted any serious adverse effects.

Conclusions: The study demonstrated that voluntary pre- exposure HCQ prophylaxis by HCWs is associated with a statistically significant reduction in risk of SARS-CoV-2.  


COVID-19, Hydroxychloroquine, Pre-exposure prophylaxis, Healthcare workers

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