If hand sanitizer kills 99.9% of viruses and bacteria then what is the remaining 0.01% ?

Your body is the host of several bacteria, a lot of which can be helpful. In fact, washing your hands too much can be harmful for you. So my theory is that they are trying to spare the beneficial bacteria.

They are the bacteria/viruses that have a resistance to the sanitiser/got lucky.

The manufacturer can’t say ‘100%’ because that would be making an easily disprovable claim. So they say 99.9% to give themselves some wiggle room (and less legal liability).

I can visualize some virus expert drone at a chemical company testing 10,000 viruses all day and making marks on a piece of paper. “8958 – worked 8959 – worked – 8960 -oops – 8961 – worked.”

Pre pandemic, doctors and scientists used to say anti-bacterials were bad because they killed the weak bacteria and the strong bacteria remained (to make more strong bacteria). Once the pandemic came, that theory disappeared.

I don’t use anti-bacterials, unless I am somewhere where the only soap available is that, or during the pandemic, when some places made you use it when you touched something. I just use soap and water and take my chances.