How long after applying hand sanitizer does it remain effective at killing most harmful bacteria?

Like ozone in air and water, hand sanitizer only works when applied. It does the job with what is present, but the antibacterial effect does not last.

The key is to wash your hands and/or apply hand sanitizer regularly. Regular soap and water, when done long enough, will wash off the film and residue on your hands that the virus is on, even if the soap itself has no antibacterial properties.

But the hand sanitizer itself only works when applied.

@yellowdog so you could apply it and a minute later your hands could be contaminated?

If you look at most hand sanitizers, the active ingredient is alcohol. It is about 60% alcohol. It will kill most germs on contact, but will evaporate quickly. The only residue left behind is the stuff the gel is made of and the fragrance used. So putting it on doesn’t continue to protect you for any real period of time. The help of hand sanitizers is that it takes germs a while to grow. Even if you touch something yucky, your hands are instantly covered in germs.
I disagree with my esteemed colleague, @Yellowdog, from the point that washing with soap and water does, indeed, help eliminate germs off your hands. But you have to wash properly. soaping your hands for about 30 seconds is necessary to help kill the germs and eliminate their little corpses.

@Ltryptophan I’m no authority on the subject, but it is likely that there’d still be some residue of the sanitizer on your hands a minute later, and it is unlikely that you are going to immediately touch the virus. Just keep washing your hands, and applying hand sanitizer or rubbing alchohol, or some anti-viral spray such as lysol.

Well, obviously, one would go through some encounter in a public space, touching door handles, et al. Then after those circumstances are concluded, or if one were to have lunch, I think applying hand sanitizer then, after some period of exposure will act to limit contracting something.

— to my question, I imagine some bactericide potent enough to remain effective on the skin for long periods might pose its own safety risks. Possibly as a skin irritant, or potentially a danger to beneficial bacteria living in our gut.

I personally don’t believe in hand sanitizers. I will use them in certain situations such as if someone asks me to do so prior to handling their new baby. But in my mind, hand sanitizers are a polite name for napalm. It burns like crazy and I just don’t think that can be good for my skin in frequent doses. Additionally, we have immune systems that need to be “exercised”. If you try killing off all germs and viruses, our immune systems get lazy and stop working correctly. Once that happens, you end up falling victim more easily to little illnesses because your system doesn’t respond quickly or efficiently and you didn’t keep trying to protect with sanitizers.

A friend is a nurse in a hospital ward for transplant patients, where the transplant recipients are on immuno-suppressant medications and vulnerable to opportunistic infections.

Protocol in her area is to use hand sanitizer on entry and exit of every patients room. So if she is making rounds, it may be moments from one application to the next.

(This is in addition to glove use.)