The science behind handwashing and COVID-19

Sam Wood

Improving hand hygiene is essential in strengthening the nation’s infection control and reducing transmission of COVID-19. Here from Dr Alexandra Moores, Lecturer in Microbiology at Kent, are some tips and a little science behind hand hygiene to aid self-protection and to protect others in our community.

‘Firstly, you need to know that COVID-19 is a virus, and that it surrounds itself with an envelope consisting of a lipid (oily) bilayer.

Effective handwashing & the science behind it:

  1. Wet hands with water and apply soap necessary to cover all surfaces
  • Soap contains surfactants, which directly affect the lipid bilayer of the virus surface, causing the virus to fall apart. The virus requires an intact structure of its lipid bilayer to be active and cause infection. Therefore, washing with soap will destroy the virus’s envelope leading to its end.
  • Estimates indicate you have roughly 5 million microorganisms on your hands. Every time you touch a surface (including your face) you transfer thousands of microorganisms. Therefore, when washing hands with soap, making sure you properly scrub over all areas is essential.
  1. Lather and scrub hands all over for 20 seconds, including in between finger webs and over the thumbs.
  • Scrubbing creates friction, this will help remove microbes from the skin.
  • Studies have shown 20 seconds is enough to remove unwanted transmittable organisms from your skin.
  • Microbes are found at high concentrations on our hands, particularly under the nails. Long and artificial nails can harbour considerably more microorganisms. Ensure nails are cut short and efficiently scrubbed when washing.
  • Finally, remember to wash under jewellery as they can shield microorganisms from the washing process. Skin beneath rings, watches, and bracelets can protect microorganisms unless you clean effectively.
  1. Rinse hands with clean water and dry for 20 seconds thoroughly using a clean towel or hand drier.
  • Microorganisms are easier to transmit from wet hands than dry hands – essentially making it their last chance to transmit before your hands dry.
  • Do not touch the tap with your clean hands (this can lead to recontamination). Instead use a towel/tissue to turn off the tap.

‘Soap is the most effective way of removing microorganisms from your hands, however alcohol based gels containing a minimum of 60-80% ethanol (check the bottle) are considered to have effective anti-microbial activity.

‘Remember, this doesn’t just help bring an end to the spread of COVID-19, but also other viruses and microorganisms such as Norovirus, methicillin resistance Staphylococcus aureus (MRSA) and Clostridium difficile.

Dr Alexandra Moores, Lecturer in Microbiology, School of Biosciences, University of Kent

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