I have seen online concerns about covid19 transmission in bathroom from spray of flushed toilet water. I am a grandma, used this very simple solution to help prevent for colds, flues at all times: shut the lid, flush the toilet. Leave it down at least a few minutes then raise if you wish. Saves your surfaces, toothbrushes and maybe you.
You forgot that South Korea is also using Oxygen therapy with zinc, Vitamin C along with whatever else. Ozone therapy is also effective especially if combined with zinc - Vitamin C **High Dose IVC** F.Y.I. China is doing the same thing, earlier this year they shipped 50 metric tones of Vitamin C, to covid 19 hardest hit areas but they did not mention much about it, like everybody else.
Preventative measures, don't wait until you feel bad. Take care of yourself, don't get rundown. Eat healthy, hydrate, get plenty of sleep.
Washing your hands properly and often and avoiding direct contact with spew from coughing and sneezing.