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.

100% – 99.9% = 0.1%, not 0.01%

The remaining 0.1%, is the viruses and bacteria that are most resistant to hand sanitizer, and some that lucked out.

@jca2 – yeah, you don’t want to selectively breed resistant bacteria.

I did that with potatoes once – planted extra potatoes, dug up the production, ate the big ones, then replanted the small ones. 3 generations later, only small ones were coming out.

Boiling water doesn’t even kill all bacteria, so it stands to reason that sanitizer doesn’t work on everything. Especially since Boiling water isn’t a factor and most people probably miss parts where bacteria can hide.