Positive impact of oral hydroxychloroquine and povidone-iodine throat spray for COVID-19 prophylaxis: An open-label randomized trial

Background: We examined whether existing licensed pharmacotherapies could reduce the spread of coronavirus disease 2019 (COVID-19). Methods: An open-label parallel randomized controlled trial was performed among healthy migrant workers quarantined in a large multi-storey dormitory in Singapore. Forty clusters (each defined as individual floors of the dormitory) were randomly assigned to receive a 42-day prophylaxis regimen of either oral hydroxychloroquine (400 mg once, followed by 200 mg/day), oral ivermectin (12 mg once), povidone-iodine throat spray (3 times/day, 270 mu g/day), oral zinc (80 mg/day)/vitamin C (500 mg/day) combination, or oral vitamin C, 500 mg/day. The primary outcome was laboratory evidence of SARS-CoV-2 infection as shown by either: (1) a positive serologic test for SARS-CoV-2 antibody on day 42, or (2) a positive PCR test for SARS-CoV-2 at any time between baseline and day 42. Results: A total of 3037 asymptomatic participants (mean age, 33.0 years; all men) who were seronegative to SARS-CoV-2 at baseline were included in the primary analysis. Follow-up was nearly complete (99.6%). Compared with vitamin C, significant absolute risk reductions (%, 98.75% confidence interval) were observed for oral hydroxychloroquine (21%, 2-42%) and povidone-iodine throat spray (24%, 7-39%). No statistically significant differences were observed with oral zinc/vitamin C combination (23%, -5 to +41%) and ivermectin (5%, -10 to +22%). Interruptions due to side effects were highest among participants who received zinc/vitamin C combination (6.9%), followed by vitamin C (4.7%), povidone-iodine (2.0%), and hydroxychloroquine (0.7%). Conclusions: Chemoprophylaxis with either oral hydroxychloroquine or povidone-iodine throat spray was superior to oral vitamin C in reducing SARS-CoV-2 infection in young and healthy men. (C) 2021 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.

Automated summary

The study found that chemoprophylaxis with either oral hydroxychloroquine or povidone-iodine throat spray was superior to oral vitamin C in reducing SARS-CoV-2 infection in young and healthy men. Participants receiving zinc/vitamin C combination had the highest rate of interruptions due to side effects.