As an aside: at the beginning of the pandemic, I was experimenting with povidone-iodine nasal sprays and mouthwashes. I did this on theoretical grounds, given that povidone-iodine is a potent antiseptic for viruses, and a study found that 0.25% povidone-iodine can kill SARS-CoV-1 in 15 seconds.
But later a randomised placebo-controlled study on 606 COVID patients in Bangladesh found 1% povidone-iodine nasal spray, throat gargle and eye drops, when administered by the patient every 4 hours, reduced the COVID death rate by 8.5 times.
In the 303 COVID patients in the study who administered 1% povidone-iodine every 4 hours as a nasal spray, gargle (mouthwash) and eye drops, and doing this for four weeks, there were only 2 deaths.
But in the 303 COVID patient placebo group applying just water, the study recorded 17 deaths.
So that is an 8.5-fold reduction in death from povidone-iodine. Which is not far behind a vaccine, which reduces death by about 20-fold.
If you are both vaccinated and use povidone-iodine, you may reduce your chances of death by 20 x 8.5 = 170 times!
So for someone who is in their 80s, for example, an age group which when unvaccinated has around a 29% chance of death once they develop symptoms and become a COVID case (ref
here), vaccination would reduce their chances of death to about 1.5%, and vaccination combined with povidone-iodine would further reduce the risk of death down to around 0.2% (or 1 in 500).
This is another third world study, so given the reliability issues of studies from developing countries, we should take this result with a pinch of salt. But at least for povidone-iodine, there are good theoretical reasons to believe it might work, given that we know it can kill coronavirus in 15 seconds on surfaces.
Unfortunately in my experiments with a 0.25% povidone-iodine nasal sprays and mouthwashes, I found povidone-iodine was fine sometimes, but on other occasions caused pain and stinging in the nose. It was always fine by oral mouthwash, but spraying into the nose would often cause pain.
I don't know if my nose is more sensitive than other people's, but I found nasal pain to limit the usefulness of povidone-iodine. If there were a way to prevent this nasal pain, I would probably apply povidone-iodine regularly, as a COVID prophylactic (preventative) when I am in high risk environments.
Edited by Hip, 25 October 2021 - 02:34 PM.