London - Such is the fear over the spread of coronavirus that panic-buying of sanitising hand gels has forced some retailers to ration supplies.
In fact, hand washing is always better for removing the virus. But gel is useful if soap and water is not available, for example while you’re out and about in public, or when you’ve touched surfaces around the office.
Research suggests frequent use of alcohol-based hand gels can stop many respiratory viruses (those that normally affect the airways, such as coronavirus) in their tracks.
Most good hand sanitisers are made of 60 percent to 90 percent alcohol (often marked as ethanol on the label) - this high level is essential.
The novel coronavirus has a type of coating that is particularly susceptible to the destructive effects of alcohol. Some other common viruses - such as norovirus, the winter vomiting bug - are impervious to this.
"A sanitiser needs to be at least 70 percent alcohol," says Professor Mark Wilcox, a microbiologist at Leeds Teaching Hospitals NHS Trust.
"Some people may be tempted to make their own, but that’s no good, because most alcoholic drinks - even the strongest ones - are only about 40 percent alcohol, which means they are unlikely to destroy the virus."
Alcohol works by destroying the protective outer membrane of the virus, causing each particle to rapidly break down. Death is almost instant.
A 2014 study by scientists from the University of Arizona in the US looked at what happened to viruses in the home when family members regularly cleaned their hands with an alcohol-based gel, as well as hand washing as normal.
They monitored a total of seven households, each comprising two parents and at least two children.
One of the adults in each home - the designated "spreader" - had their hands coated in a liquid containing infectious viruses and bacteria.
After eight hours, the scientists found signs of contamination on each family member’s hands, as well as frequently used surfaces throughout the home.
In other words, the virus was running wild.
They then repeated the experiment, but this time placed bottles of sanitising hand gel all over the house, advising volunteers to use them up to three times a day.
The results, published in the journal Food And Environmental Virology, revealed this reduced the level of viral contamination on hands and surfaces by a huge 99 percent.
Other experiments by the same researchers found the spread of viruses in the workplace is cut by 84 percent when employees are encouraged to use alcohol gel routinely throughout the day.
"I have started to use hand gel much more often if I am moving around at work or travelling," says Professor Wilcox.
"The other day I counted how many surfaces my hands came into contact with in just an hour of moving around, such as door handles and stair rails. It was roughly ten."
Professor Wilcox advises using a gel every time our hands have been in contact with potentially contaminated surfaces - for example, after using public transport or going to the shops or any public place.
But what of the advice from some experts that you should wash your hands and then use a hand sanitiser?
Professor Wilcox says: "Using alcohol gel after hand washing can be seen as a belt-and-braces approach. But if your hand washing technique is good, it’s not really necessary."
When you do use sanitisers, you must do so properly in order for them to work.
"Most dispensers are designed to squirt out one application - enough to cover the whole hand," says Professor Wilcox.
"The issue is not the amount you use, but whether you rub your hands together properly so that the gel is applied to all parts of your hand. If not, it doesn’t matter how much you put on.’ That means getting right in between the fingers and thumbs, as well as covering the backs of the hands and each wrist.
"I see so-called experts on TV demonstrating how to apply hand gel while they are wearing a watch," says Professor Wilcox. "You cannot apply it properly if you have a watch on - it has to include the wrist as well."
That’s because if you put your hand anywhere near your face, the viruses can still be transmitted from your wrist to your mouth, nose or eye. These are the main entry points for coronavirus.