Positive impact of oral hydroxychloroquine and povidone-iodine throat spray for COVID-19 prophylaxis: an open-label randomized trial (April 14, 2021) - also suggests ivermectin less effective than HCQ - but ivermectin was given only once while HCQ was given daily over a period of 42 days

stereomatch | 6 points | Apr 16 2021 23:59:10

https://www.ijidonline.com/article/S1201-9712(21)00345-3/fulltext Positive impact of oral hydroxychloroquine and povidone-iodine throat spray for COVID-19 prophylaxis: an open-label randomized trial April 14, 2021

Highlights

We studied chemoprophylaxis agents that could reduce spread of SARS-CoV-2 infection.
Oral hydroxychloroquine and povidone-iodine throat spray reduced SARS-CoV-2 infection.
Oral hydroxychloroquine and povidone-iodine throat spray use were well-tolerated.
Infection rates did not significantly differ with oral ivermectin and zinc/vitamin C.
Two repurposed agents reduced spread of COVID-19 in high transmission settings.

Abstract

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 µg/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 3,037 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.

ClinicalTrials.gov number

NCT04446104

NOTE:

Ivermectin showed less impact than HCQ+povidone. However HCQ+povidone were given daily, but perplexingly ivermectin was once only (not even weekly) - as such this has similarities with the AIIMS-Bhubaneswar, India study of healthcare workers:

https://www.reddit.com/r/covid19/comments/llp8d0 Role of ivermectin in the prevention of SARS-CoV-2 infection among healthcare workers in India: A matched case-control study

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0247163 Role of ivermectin in the prevention of SARS-CoV-2 infection among healthcare workers in India: A matched case-control study February 16, 2021

These were given 2 day dose of ivermectin and then observed for 30 days (here HCQ perhaps because of it's one time dose did not perform). And even ivermectin may have protected for one or two weeks, but those infected later would have shown less impact (since Ivermectin does have dose dependent response as seen from the taste/anosmia studies, and in the view of Dr Andrew Hill as well).

So with this Singapore study, how long did they observe the participants - was it also over month like the AIIMS-Bhubaneswar, India study?

No, it was even longer ie 42 days:

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 µg/day), oral zinc (80 mg/day)/vitamin C (500 mg/day) combination, or oral vitamin C, 500 mg/day.

Which may explain why ivermectin would lag, while the other treatments would have an advantage as they were given every day.

Interestingly, ivermectin had no side effects (at least for the single 12mg doses they gave). Though we already know that, even for 10x that dose from the Merck safety study from 2002 or thereabouts.