Last updated: 5 May 2020
We're all now hyper aware of hand hygiene due to the coronavirus pandemic, but confusion remains about exactly what works best and why.
We know that across the UK (and beyond), alcohol-based hand gel is like gold dust at the moment.
It's important to remember that hand sanitiser isn't the be all and end all of hygiene (if you're one of the millions of Brits now mostly staying at home anyway, hand washing is the best option).
But does it matter what kind of hand gel or soap you buy? And what can you do if you're struggling to get hold of these products?
We spoke to a microbiologist about the science of hand sanitiser and soap, the key ingredients to look for and whether alternatives such as hand wipes work.
It's all about the type of virus we're dealing with.
COVID-19 is an enveloped virus. This means that the RNA (nucleic acid - the viral genetic material) is coated in a lipid (fatty) layer.
Soap is able to dissolve this lipid layer, causing the virus to fall apart and stopping it from binding to our cells.
Alcohol-based hand sanitisers work in a similar way, inactivating the virus by breaking down the lipid layer.
You've probably seen that you need at least 60% alcohol content for hand sanitiser to work properly.
Dr Primrose Freestone, associate professor in clinical microbiology at the University of Leicester, explains that this is because 60-95% alcohol content is the level needed for it to work to inactivate viruses including COVID-19.
Most alcohol-based hand sanitiser gels contain one or more alcohols: ethanol, isopropanol - or a combination of the two. You can check the label to see how much it contains.
We checked the main high street brands and Carex has the highest alcohol content, according to the information on the label:
*If you have a Cuticura product, you might notice that on the label it says it contains 57.6% ethanol. Cuticura told us that this is the value by weight and it converts to 66% ethanol by volume (the important measure), which is above the 60% minimum requirement.
The pitfalls of hand sanitiser are that it doesn't work as well on sweaty, greasy or visibly dirty hands, and you need to use a lot to completely cover the entire surface of your hands.
Repeated use of alcohol-based hand sanitiser can irritate your skin, too, despite many containing moisturising agents.
Alcohol-free hand sanitisers are usually foams, such as the two pictured above.
They can be gentler on the skin but the scientific evidence varies more for alcohol-free products than it does for sanitisers containing alcohol.
Alcohol-free hand sanitisers commonly contain ingredients such as benzalkonium chloride or chlorhexidine digluconate. A recent study in the Journal of Hospital Medicine (March 2020) found these ingredients less effective in deactivating viruses similar to COVID-19 (although the study looked at surfaces not hands).
Dr Freestone explained to us that these ingredients tend to work better against bacteria and viruses such as norovirus, reiterating it is 'alcohol, detergents, hydrogen peroxide, extremes of pH and bleach that inactivate COVID-19'.
As Dr Mark Webber, research leader at the Quadram Institute, explains: 'The reason that alcohol-based sanitisers are prioritised in official World Health Organization and NHS guidance is that the evidence for it is much clearer (as with soap and water). Other chemical compounds have varying efficacy, but it's harder to be sure.'
This doesn't contain alcohol and one of its active ingredients is primarily antibacterial. But it also contains didecyldimonium chloride.
Dr Freestone says this ingredient 'causes disruption of intermolecular interactions and dissociation of lipid bilayers, and might act on an enveloped virus such as COVID-19. However, it hasn't been tested against this virus specifically.
Also stocked at Boots, this contains benzalkonium chloride and another ingredient, didecyl dimethyl ammonium chloride, which was shown in the Journal of Hospital Medicine study to have some effectiveness against a related coronavirus.
EcoHydra recently announced that its antimicrobial/antiviral hand sanitiser range has been certified by independent laboratories as effective against all coronaviruses, including SARSu2010CoVu20102
Medical grade sanitisers, such as Defendol (above) usually have around 70% alcohol and will have been tested to show specific pathogen-killing efficacy relevant to hospital settings.
But Dr Freestone says the average person shouldn't need to seek this out, as standard alcohol gels are still effective.
Hospitals and medical environments understandably need protection that has been certified for high-risk environments, so it's best to leave this for those who really need it.
You can theoretically make your own, by mixing 3/4 cup of rubbing alcohol with 1/4 cup of aloe vera, but it's not really advisable. Anything homemade is obviously not laboratory validated to the standard of commercial hand sanitisers.
You would need to ensure you use sterilized containers and source some isopropyl or rubbing alcohol. This is 99%, so that bottle of vodka on the shelf won't do the trick. Like other raw ingredients associated with popular coronavirus items, it's also currently hard to get hold of.
As long as you wash your hands after contact with the outside world and avoid touching your face before you've done this, you shouldn't need to worry too much about hand gel.
Some pharmacy chains have been redirecting customers to stocks of antibacterial wipes when their hand gel stocks are out. But is it really the same thing?
Dr Freestone says: 'Wipes tend to have less alcohol and more antibacterial compounds such as benzalkonium chloride (used in Wet Ones), as well as water and wetting (detergent and surfactant) agents. Before buying the wipes, you should check the range of pathogens the wipe is active against by searching the back of the packet, or checking the active ingredients online.'
These types of wipes, along with antiseptic creams such as Savlon or Germolene, tend to be more antibacterial than antiviral, as they're designed to work on the skin where bacteria are (usually) the main skin pathogens.
As with hand sanitiser, you may be happy to go with whatever soap you can find on the shelf. And it turns out, there's no need to be too discriminating. If it foams, it will do the job.
The good news is this means there are alternative options if you can't find any soap nearby.
Liquid soap and solid soaps have different ingredient formulations, but the principle of their mechanism of cleaning action is the same, so it doesn't matter which you buy.
Broadly, traditional solid soap bars tend to be made from a combination of fat or oil, water and an alkali substance such as lye. Liquid soap, or hand wash, is made from synthetic detergents, such as sodium lauryl ether sulfate, instead.
Ideally, choose one with moisturising agents, as this will help to offset frequent hand washing. Most modern hand soaps will include these, though.
There's no need to pay extra for or hunt down products that carry specific 'antibacterial' claims on their label.
As Dr Freestone says: 'The detergents and surfactants (wetting agents that reduce the surface tension of water) in any type of soap are innately antibacterial in that they remove surface-attached bacteria and viruses.'
So your soap may not call itself 'Germ Shield' or similar, but it will still do the same job as long as you wash your hands in the proper way.
If you're really struggling to find hand soap, this is probably the next best thing.
Dr Freestone says: 'All detergents work similarly and many hand or body cleaning products have some of the same agents present as hand soap. For example, sodium lauryl ether sulfate is found in shampoo, shower gel and washing-up liquid (although this might be harsher on your skin as it's designed for tough grease on dishes).'
Like with surgical masks, Public Health England and the NHS have not recommended the use of surgical or latex gloves as a protective measure for the general public against COVID-19.
While it's true that gloves provide a barrier between your hands and other surfaces, they might give people a false sense of security, can be wasteful as they need to be disposed of after use and hand washing is a better preventative measure anyway. Prolonged wear may also irritate your hands.