Effect the pre-exposure prophylactic of hydroxychloroquine on severe covid-19 disease: a randomized controlled trial

Background. In vitro studies have shown some effects for Hydroxychloroquine (HCQ) against SARS-CoV-2 virus. Despite effective vaccination program, relatively large proportion of population remains unvaccinated. So, there still remains a need for other prophylactic measures. The present study aims to evaluate whether HCQ can prevent severe COVID-19 outcomes among health-care workers. Materials and methods. In this randomized, double blind placebo- controlled clinical trial 334 healthcare workers aged 18-65 years old were included of whom 278 individuals completed the study. Participants were randomly assigned to the HCQ group (800 mg at day one, followed by 400 mg weekly for the next 7 weeks); or the placebo group. Participants were followed three weeks after the last dose of drug or placebo (10 weeks from the first dose of drug or placebo). The primary outcome was hospitalization or death from COVID-19. Results. Of 148 people who received HCQ, none were hospitalized or died from COIVD-19, while of 130 people who received the placebo, 2 (1.5%) were hospitalized for COIVD-19 ( p-value: 0.26). And, 22 (14.9%) people in the HCQ group and 15 (11.6%) people in the placebo group contracted COVID-19 (p-value: 0.99). Adverse reactions were reported by 5 (3.4%) of participants in the HCQ group and 5 (3.9%) of participants in the placebo group ( p-value: 0.99). Conclusion. We found that HCQ has no significant prevention effect on the incidence of mild COVID-19. However, the low rate of hospitalization (the primary outcome) in this trial like most of the other clinical trials with HCQ would have required increasing the sample size considerably to be able to comment on the effectiveness of HCQ in prevention of severe forms including death rate. This justifies systematic reviews to include similar studies to further investigate the issue.