Skin Diseases & Skin Care

Perspective

From January 2020 to May 2021, approximately 170 million people were infected with COVID-19, and approximately 3.6 million died as a result of the illness. SARS-CoV-2 is the virus that causes the disease (severe acute respiratory syndrome coronavirus 2). The primary mode of transmission, according to the US CDC in 2020, is close contact or inhalation of respiratory droplets. Some diseases can also be transmitted through contaminated solids (fomites), and according to the World Health Organization, "fomite transmission is considered a likely mode of transmission for SARS-CoV-2."

A hamster study found that direct inhalation is the most common mechanism, but infection via fomite transmission also occurred. Modeling of the pandemic and disease transmission revealed that up to 25% of disease transmissions during lockdown occurred via fomites. SARS-CoV-2 remains infectious for up to 7 days after a droplet is placed on some solids, indicating that the window of possible infection from solids may be large. This has resulted in widespread fear of touching communal objects, as well as health officials advising people to increase the frequency and quality of their hand-washing. A parallel approach would be to develop virus-inactivating coatings for solids and apply these coatings to communal objects.

The most common way for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to spread is through airborne transmission of droplets from an infected person's exhalation, cough, or sneeze. However, there is evidence that the virus can spread when people come into contact with contaminated surfaces (known as 'fomites,' with studies showing that the virus can live on many surfaces for a few days.

This has caused many people to be afraid of touching objects they use. Hand washing and sanitization of communal objects are recommended by public health guidelines. Another method for avoiding this problem is to coat objects with a virus-killing coating. However, whether the virus is actually transmitted from the contaminated object to the skin is still unknown.

Using artificial skin to test virus transfer

Because transmission to real human skin is not possible due to biosafety concerns, the team used an artificial skin called Vitroskin®, which has properties that are very similar to natural human skin and has been shown in studies to be a good human skin model.

The team created an artificial plastic finger and wrapped it in artificial skin. They tested each solid surface with a droplet of a SARS-CoV-2 suspension. They contacted the artificial skin with this contaminated solid for 10 seconds or 30 minutes, then removed the skin and placed it in a solution to remove the virus. The virus solution was tested for its ability to infect Vero E6 cells. They calculated a transfer ratio, which is the ratio of virus infectivity on the finger to the original droplet's infectivity.

They discovered that when a virus-infected wet droplet is present on a surface, even a brief, light touch can transfer the virus to the finger. The transfer ratio was approximately 13-16 percent for glass, stainless steel, and Teflon surfaces. Touching the surface after the droplet had dried transferred less virus, approximately 3-9 percent. Because infected people can shed a large amount of virus, the amount transferred can be quite large.

Although this is less than that of a wet droplet, it is not less biologically. Effective disinfectants leave less than 0.1% of germs on the surface, emphasising the importance of washing our hands before touching our faces.

Washing hands critical to prevent transmission

The virus transfer tested here required only gentle pressure and a quick touch. Normal contact typically entails more time, varying pressures, and varying rubbing motions. Rubbing will almost certainly result in more virus transmission.

Infection necessitates another step in which the virus is transferred from the skin to the respiratory system, emphasising the importance of handwashing once more. Although the infectious dose for humans is unknown, only five virus particles are required to infect a Syrian hamster.

According to research, the virus can survive on the skin for at least several hours. Thus, even after the virus suspension has dried, contaminated surfaces, particularly non-porous surfaces, can transfer virus to the skin. Thus, handwashing is an important part of avoiding SARS-CoV-2 infection.