Scan around NIH etc and you'll probably find several studies looking at a 1% solution of Johnson and Johnson baby shampoo. I haven't kept up on their results, but I was looking for something like this about a year ago and finding that I assumed it must be safe. I've done it twice and both times it seemed much more effective than just the salt stuff alone, but if you overdo it you get nasty tasting bubbles in the throat--the bubbles are a little annoying, but they sure could leave out the scent. 4 drops in about 5 ounces was milder and still seems to have worked.
The studies are looking to kill virus with it (works really well in vitro) but regardless of that the solution just breaks stuff up better. I don't find irrigation all that helpful without it.
My doctor has been more concerned, which is why I've had to go for two negative tests. I'm compromised and historically that's translated into every bug lasts 2x longer for me than my wife. So far this is the exception. As he's mentioned, negative tests and the very mild symptoms reinforce that disease and immunity are not binary.
They really should update the vaccines, but it's not that or nothing. I held off on #4 until it looked like the update was delayed and I was about to travel but now I'm glad to have it. Dude in Germany took 87 shots. I never get anything but a sore arm. Pretty easy decision at this stage.