Many Australians are unaware they are using hand sanitiser that is ineffective, particularly in preventing transmission of coronavirus, experts fear.
Hand sanitiser has rapidly been selling out in shops for weeks, but there are concerns that variations in alcohol levels mean some are not providing adequate protection.
"It's dangerous in that they may not work anywhere near as well as you'd expect," Peter Collignon, professor of infectious diseases at the Australian National University, said.
Across Australia, there are thousands of products that are marketed as hand sanitiser, but not all are equal.
The least effective are sanitisers that contain no alcohol.
These are often chosen by customers who have suffered a reaction to alcohol-based products, but buyers are warned they offer a low level of protection.
"I think it might provide them with a false sense of security," Andrew McLachlan from Sydney University's School of Pharmacy said.
"If you're out and about and you need to use the bathroom and you want to reduce your risk of infection or exposing yourself to bacteria, then the alcohol-free products are probably fine for that.
"But when it comes to viruses, where we're trying to inactivate them, that is much more effective with alcohol-based hand sanitiser."
Low-alcohol sanitisers 'should be avoided'
Experts warn not to reach for just any alcohol-based sanitiser.
A nice-smelling spray with 30 per cent alcohol content can be virtually useless at killing viruses, particularly if used in the same doses as high-alcohol content sanitisers usually are.
"30 per cent might be better than nothing, but it would take longer to work and require greater volume than an appropriate-strength one," Professor Collignon said.
"The trouble with low-alcohol sanitisers is that they might not have been tested or approved with data showing they will work, so they should be avoided if they can."
Experts say the gold standard is a sanitiser with 60–80 per cent alcohol — the level required to kill the virus if it is on your hands.
"The high-alcohol-based sanitisers are the most effective at killing not only the bacteria but the particular types of virus," Professor McLachlan said.
"They do so by disrupting their outer membranes or envelope, and that won't happen unless there's at least 60 per cent alcohol content."
Too much alcohol is a problem too
What is not effective, though, is 100 per cent alcohol, because water is necessary to make sanitisers effective.
It's a message the World Health Organisation (WHO) is hoping to get out with the release of formulas for making alcohol-based sanitiser at home.
"100 per cent alcohol is nowhere near as effective as 70 per cent, for instance, so getting the right concentration is important," Professor Collignon said.
Ultimately, the best way to stay safe is to stay home — and when it comes to keeping hands clean, washing them thoroughly in warm soapy water is more effective than any hand sanitiser.
"None of them are helpful unless you're minimising your touching practices and using good hand hygiene," Professor McLachlan said.
"So, making sure you're avoiding high-touch surfaces like ATMs, handrails, lift buttons, using other parts of your body like elbows, knees or feet to open doors, and also not touching your eyes, face and nose.
"These are the things that are so important."
Article from ABC News