https://www.betadine.com/sore-throatWhen I feel my throat acting up a bit I gargle with " Betadine Solution Povidone - Iodine 10%".
Dilute it to another 10% for the gargle.
https://www.amazon.com/Povidone-Iod...ne+solution+povidone-iodine+10%,aps,71&sr=8-7
The item I link to is a lot less expensive than the prediluted. Just dilute it for gargling.