Science Questions

How do disinfecting hand-rubs work?

How do hand sanitizers work, and how effective are they against viruses? Robert

Chris -  It depends what virus you’re dealing with.  If you’re dealing with 'flu, they work quite well because 'flu is what’s called an enveloped virus. On the surface of the virus particle is an oily bag which, if you add alcohol from a hand rub or cleansing gel, breaks it apart, denaturing the virus.

If, on the other hand, you’re playing around with something like norovirus, the winter-vomiting bug, this does not have one of these oily envelopes around the outside of the virus; these are known as non-enveloped viruses. Instead they comprise a very tough particle assembled from proteins linked together. As a result of it does not respond to alcohol in disinfecting hand rubs.  These are impervious to the alcohol in hand rubs, so these sorts of cleansers are not effective against viruses like noro. All all you get is a pure culture of norovirus on your hand after using one! Instead, the way to deal with these is actually soap and water; not because the soap kills the noro but by rubbing the skin actually detaches it and this gets rid of it.

December 2009