Why hand-washing?

Nina Shapiro, a professor of medicine at UCLA:

What is it about soap that gives it such superpowers?

Plain old hand soap, no, not antibacterial soap (remember, this is a virus devastating us, not a bacteria), contains molecules that are actually called “soap molecules.” They contain a hydrophobic (water-hating, or water-fearing) end and a hydrophilic (water-loving) end. When mixed with water, the components of a soap molecule line up so that the water-loving ends are facing out, and the water-hating ends are facing in.

When dissolved in water, the components in soap form circular “micelles,” exposing all of the water-loving ends outward. The coronavirus is coated with lipids and proteins. The hydrophilic (water-loving) component of soap acts to dissolve the lipids and break down the proteins, both of which actions help prevent the virus from entering the cells on the skin. Hand sanitizer containing at least 60% alcohol also has effects on this virus. The alcohol acts to disrupt RNA molecules in the virus, preventing viral replication (in other words it blocks the virus from making copies of itself). But soap is slightly superior, as there is the scrubbing part that comes with hand washing with soap and water.

The World Health Organization (W.H.O.) has provided a now highly viewed poster about hand washing technique, which emphasizes not only coating the hands with soap and water, but also includes rubbing the soap into the skin for at least 20 seconds (with the song, meme, or Shakespearean monologue of your choice these days). The duration is critical, as it ensures a more thorough cleansing, as opposed to just a surface once-over one tends to do with hand sanitizers or wipes. Unlike hard surfaces such as tables, door knobs, or computer screens, skin has a more irregular, variant texture, whereby a light coating followed by a three-second rinse just won’t do the job.

Just wash your hands. With soap. And after that, dry them. With a towel (disposable these days). Towels enable one to continue to use a bit of friction on the skin, which helps remove dirt and pathogens.

Bathroom hand dryers are a big “no” these days. In 2018, a study published by the American Society of Microbiology found that these dryers literally suck up bacteria from fecal matter in the bathroom air, and spray it on each user.

(Source)