- Using sanitisers and wipes to kill the SARS-CoV-2 virus on surfaces is very important during the Covid-19 pandemic.
- However, wipes and disinfecting sprays don't always produce the best results.
- Wipes may be more effective than sprays because some sprays don't contain the right amount of alcohol.
Since the Covid-19 pandemic hit South African shores earlier this year, retail stores have been doing their best to battle the spread of the virus.
In addition to the usual disinfectant trolley wipes, most stores have an employee at store entrances to spritz trolley handles with sanitising liquid - often contained in an unlabelled bottle.
However, some disinfectants may not contain the correct levels of alcohol to effectively kill the SARS-CoV-2 virus.
Rhodes University tested sanitisers at an Eastern Cape boarding school, where more than 200 staff and pupils tested positive for the virus this year, and found that they only contained only 57.6% alcohol – less than the required minimum alcohol content, News24 reported.
According to the Centers for Disease Control and Prevention (CDC), alcohol-based sanitisers need to contain at least 60% alcohol to effectively kill the virus.
Spraying trolley handles is no guarantee
According to Bernard Reeksting, chemical scientist and former director of the Centre for Polymer Technology at the CSIR, even if a spray kills SARS-CoV-2, it may not necessarily be the most effective way of disinfecting surfaces.
"Spraying a trolley handle with a sanitiser only acts as a wash-down, given that its distribution is wide and somewhat erratic, which means that much of its effect will be wasted in the atmosphere.
"A spray therefore provides no guarantee that the sanitiser is evenly distributed as it is likely to only land in the spray direction," he explains.
In fact, some studies have shown that disinfectant wipes produce better results on public surfaces compared to spray disinfectants.
One also needs to bear in mind that some products that claim to sanitise surfaces only kill bacteria - not viruses - so it's best to read product labels carefully. It is also a good idea to look at how long you should wipe the surface. Different products are tested under different conditions and have different recommendations.
Haley Oliver, a microbiologist and associate professor of food science at Purdue University, told the New York Times that if, for example, a product suggests you should use it for four minutes, the total wiping and drying time should be four minutes.
Why are wipes the better option?
Reeksting explains that wipes mechanically clean soiling from a surface and reach areas where bacteria and viruses may be trapped.
"The wipe acts as a reservoir to retain fluid which allows it to be evenly spread over the surface being cleaned and then actively and mechanically removes pathogens from the surface and brings them into close contact with the wipe fluid."
So what is the best way to remove all pathogens from surfaces?
According to the World Health Organisation (WHO) and CDC, handwashing with soap and running water is still the best method. This is because of the nature of soap molecules. When suspended in water, they pry apart and destroy viruses, according to an article by Global Handwashing.
However, when soap and running water is not convenient, disinfectant wipes are the second-best recommended option because they physically remove dirt and microorganisms from the surface of trolley handles. Marketing director of Infection Protection Products, Annette Devenish, recommends a second wipe, as this will ensure even better disinfection.