COVID-19 Prophylaxis with Doxycycline and Zinc in Health Care Workers: a Prospective, Randomized, Double-Blind Clinical Trial.

Objectives: This study aims to assess the efficacy of a combination treatment of doxycycline and zinc in the primary prevention of COVID-19 infection in Tunisian health care workers compared with two control groups.Methods: We conducted a prospective, randomized, double-blind clinical trial over 5 months to deter-mine the efficacy of a preventive combination treatment dose of doxycycline (100 mg/day) and zinc (15 mg/day), compared with a single-dose treatment with doxycycline versus placebo. The effectiveness of preventive treatment was measured by the significant decline in the number of cases of COVID-19 infec-tion and/or a decrease in the viral load as determined by SARS-CoV-2 cycle threshold value using reverse transcription polymerase chain reaction tests.Results: We detected a significant decrease of SARS-CoV-2 infection in the group that received both doxycycline and zinc compared with other participants. We also demonstrated that COVID-19 infection was neither associated with diabetes ( P = 0.51) nor associated with hypertension ( P = 0.99), asthma ( P = 0.52), and chronic obstructive pulmonary disease ( P = 0.27).Conclusion: Our findings indicated that preventive therapy reduced the risk of SARS-CoV-2. These results suggest that the combination of doxycycline and zinc has a protective effect in patients with SARS-CoV-2 infection.(c) 2022 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )