Skin-friendly cleansers may be just as effective against virus transmission as alcohol-based hand sanitisers and harsh soaps, according to a new study from the University of Sheffield.
The research also showed that the viral-killing ability of products differed between enveloped and non-enveloped viruses, leading the authors to suggest that novel handwashing products should be developed for the latter.
The official NHS mantra during the COVID-19 pandemic was that hand washing with soap and warm water for the time it takes to sing 'Happy Birthday' twice (around 40 seconds) was fundamental to stopping spread of coronavirus and other viruses. NHS advice was that if a person did not have "immediate access to soap and water" then they should use alcohol-based hand sanitiser where available.
Irritant Contact Dermatitis Increased Four Fold Following NHS Advice
During the pandemic, the incidence and severity of irritant contact dermatitis amongst healthcare professionals increased from 20% to 80%. The problem developed when chemical or physical agents damaged the skin surface faster than the skin could repair itself. Frequent hand washing is a contributing factor to irritant contact dermatitis of the hands, which accounts for 70% - 90% of all occupational skin diseases in Europe and the USA, said the study authors.
They noted that professionals were at increased risk because of their need for frequent handwashing, and that the condition had "a multitude of negative effects" including decreased compliance with proper personal protective equipment, inadequate hand washing, and, consequently, increased carriage of bacteria and viruses on the skin.
Healthcare personnel typically managed their condition by replacing harsh soap or alcohol-based hand sanitisers with cleansers containing mild surfactants and/or emollient ingredients – dubbed skin-friendly cleansers – to mitigate skin damage, and/or used topical emollients after washing for repair.
Limited Evidence on Virucidal Efficacy
Yet despite the widespread use of gentler cleansing products for handwashing, there was limited evidence supporting the antiviral efficacy of these products to prevent propagation of viruses such as human coronavirus, herpes simplex virus, norovirus, or influenza.
The researchers, from the Sheffield Dermatology Research group, therefore tested multiple handwash products – including antibacterial soap, natural soap, foam cleansers, and bath wash products – to investigate their ability to kill both enveloped viruses – such as human coronavirus and influenza, which have an additional layer of structural protection – and non-enveloped viruses, such as norovirus and adenovirus.
Their findings, published in Frontiers in Virology, showed that gentle cleansers were as effective as harsh soaps in killing enveloped viruses. Virucidal activity was little affected by water type (soft or hard) or pre-exposed hand hygiene conditions (clean or dirty).
In contrast, non-enveloped viruses displayed resistance to all hand wash products tested, both skin-friendly cleansers and harsh soaps. Norovirus – the winter vomiting bug – was found to be the most resilient.
Handwashing Insufficent for Controlling Norovirus
Non-enveloped viruses were killed only by bleach-based disinfectants, which were not a feasible option for washing hands, the researchers said. First author Natalie Winder, a PhD researcher at the University of Sheffield's Department of Oncology and Metabolism, said: "Even when we increased the exposure of norovirus to the handwashing products from 20 seconds to one minute, the virus wasn't disrupted.
"Bleach was the only agent which affected the virus – however, bleach-based hand washes are not a feasible option due to its corrosivity, which would be extremely harmful to the skin.
"Norovirus can spread very easily – it takes just 18 norovirus particles to infect another person, as opposed to 1000 coronavirus particles needed to spread the infection. Our findings show that although good hand hygiene practices are important to preventing the spread of many viruses, they are insufficient at controlling the norovirus.
"Measures such as isolation and disinfecting surfaces with bleach are more effective in preventing the spread of the norovirus infection, and more research needs to be done to see whether heavily diluted bleach-based hand washes, which are safe to use on the skin, can be produced."
Unintended Adverse Effects
Lead author Dr Munitta Muthana, a senior lecturer at the same university department, said: "Washing our hands with soap and warm water for 20 seconds was a fundamental message advocated in the UK to help stop the spread of COVID-19. But for healthcare professionals, who can wash their hands as many as 100 times during a 12 hour shift, this may cause unintended adverse effects.
"Not only does irritant contact dermatitis cause the skin to become inflamed, blister and crack, which increases transmission of bacteria and viruses, it can also lead to less compliance with personal protective equipment and inadequate hand washing for fear of making symptoms worse. The disease can also significantly impact workplace productivity.
"For the first time, our study has shown substituting harsh soaps with milder wash products such as gentle cleansers is effective in fighting against enveloped viruses, including human coronavirus, which is very encouraging – especially for those in jobs in which irritant contact dermatitis is an occupational hazard. We also found that using additional agents such as moisturisers to help protect the skin didn't prevent the products' antiviral activity, which means we don't have to use very harsh products on our skin in order to kill viruses."
Financial support for the study was provided by the University of Sheffield Institutional Open Access Fund and skincare manufacturer CeraVe under a grant from L'Oréal.
Author Natalie Winder declared she was employed by company L'Oréal.