Gentle cleansers are just as effective in killing viruses—including coronavirus—as harsh soaps, according to a new study from scientists at the University of Sheffield, U.K.
The findings were published in Frontiers in Virology.
In a press release, the investigators note that the incidence and severity of irritant contact dermatitis increased to 80% from 20% among healthcare professionals during the Covid-19 pandemic, in part due to frequent hand-washing with strong soaps and cleansers damaging their skin’s barrier function.
Lead author of the study, Dr. Munitta Muthana from the University of Sheffield’s Department of Oncology and Metabolism, 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 the transmission of bacteria and viruses, it can also lead to less compliance with personal protective equipment (PPE) and inadequate hand washing for fear of making symptoms worse,” said Dr. Muthana. “The disease can also significantly impact workplace productivity.”
They write that despite the widespread use of gentle cleansing products for handwashing, there has been limited evidence to show the antiviral efficacy of the products to prevent the spread of viruses such as human coronavirus, herpes simplex virus, norovirus and influenza.
To assess and compare antiviral efficacy, the researchers tested multiple handwash products as part of the study. These included antibacterial soap, natural soap, foam cleansers and bath wash products. The researchers investigated the products’ ability to kill both enveloped viruses—such as human coronavirus and influenza—compared to non-enveloped viruses, such as norovirus and adenovirus. The viruses they tested against include human coronavirus (HCoV), herpes simplex virus (HSV)-1, influenza (IVA), adenovirus (Ad), and murine norovirus (MNV).
The findings show gentle cleansers were effective in killing enveloped viruses, but non-enveloped viruses displayed resistance against skin-friendly cleansers, as well as against harsh soaps.
“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,” said Dr. Muthana. “We also found that using additional agents such as moisturizers 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.”
The study also found that non-enveloped viruses demonstrated greater resistance across all types of hand-washing products tested, including harsh chemical substances and milder solutions. Norovirus was the most resilient.
The first author of the study, Natalie Winder, 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 their 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 1,000 coronavirus particles needed to spread the infection. Our findings show that although good hand hygiene practices are important to prevent the spread of many viruses, they are insufficient at controlling the norovirus,” she said.
“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.”
The study was conducted by the University of Sheffield and funded by CeraVe.