COVID-19, Herpes, and Flu Virus Easily Susceptible to Soap

Skin-friendly cleansers (SFCs) could be a suitable alternative to soap for health care professionals looking to curb their irritant contact dermatitis following frequent hand-washing used to prevent COVID-19 and similar viruses, according to a paper published in Frontiers in Virology.

Investigators from the United Kingdom conducted an in vitro analysis using plaque assays and tissue culture infectious disease doses in order to assess virus infectability after incubation with the test soaps.

“Washing hands thoroughly with soap and lukewarm water more often and for at least 20 [seconds] is a fundamental measure advocated worldwide to help control the spread of infectious viruses, including COVID-19,” the study authors wrote. “However, these practices are causing unintended adverse effects on skin integrity, which particularly affect health care professionals.”

Over the course of the COVID-19 pandemic, the incidence of severe irritant contact dermatitis among the health care professional population increased from 20% to 80%. The severity also increased, noted the investigators. Their aim was to determine the efficacy of SFCs against enveloped and non-enveloped viruses to protect health care professionals and the wider public from irritant contact dermatitis while also protecting them from the viruses.

The study authors examined the performance of multiple hand-washing products and SFCs against COVID-19, herpes, influenza, adenovirus, and murine norovirus. The study authors explained that they used transmission electron microscopy (TEM) to determine the virus architecture and size and used PCR testing to measure the viral replication.

Non-enveloped viruses (such as adenovirus and norovirus) showed a greater resistance to all types of washing compared to enveloped viruses (COVID-19, herpes, and the flu). These non-enveloped viruses demonstrated little to no change in viral titer after use with all products. Additionally, the study authors found that increasing the wash time did not alter these results.

The water hardness impacted the antiviral activity of different wash products, the investigators learned. Most products demonstrated antiviral properties, although they noted natural soap did not present antiviral properties against herpes. The antiviral properties of natural soap were demonstrated against herpes when the product was diluted in hard water, though. But non-enveloped viruses showed resistance to most hand washing products regardless of water type. Trends were similar when the investigators increased the washing time again.

Using TEM, the study authors observed morphological changes to the enveloped viruses after incubation with synthetic and natural soaps. Contrastingly, the investigators determined that non-enveloped viruses underwent no distinct changes to their size, shape, or architecture after using SFCs.

“This indicates that these products are not capable of inducing morphological changes, which may potentially contribute to the non-enveloped viruses’ sustained infectivity,” the study authors wrote.

The viral envelop is already known to be destabilized in the presence of harsh surfactants, the study authors said, which aligns with the results of their study: All enveloped viruses were susceptible to both synthetic and natural soaps. However, these surfactants exert the same effects on the skin oils which help maintain skin health and if disrupted, can lead to epidermal damages.

“A balance needs to be found between effective antimicrobial protection and mitigation of skin damage,” the study authors concluded. “The SFCs used within our study contain milder surfactant mixtures, designed to reduce skin damage. Most SFCs tested demonstrated antiviral effects.”