The Centre for Disease Control and Prevention (CDC) recently conducted a study in March 2020 on the transmission vectors of COVID-19 in hospital wards in Wuhan, China. The study found that the coronavirus was widely distributed on floors throughout the hospital, even in areas that did not have direct contact with infected patients. Gravity and air flow cause most virus droplets to float to the ground, where they can be picked up by shoes and carried to new areas.
The CDC study shows that 50% of the shoe bottoms of ICU medical staff tested positive for coronavirus, and theorizes that contaminated shoes spread the virus to areas that had no direct contact with COVID-19 patients. The study authors highly recommended that persons disinfect shoe soles before walking out of wards containing COVID-19 patients.
While this study was conducted in a hospital setting, the information learned as a result can be carried-over into everyday life applications. Shoes are one of the main points of contact in public places, and the floor is the surface that every person entering a space comes into direct contact with. As a result, people can easily spread viruses and other harmful pathogens via the bottoms of their shoes, especially when wearing shoes with normal treads that have multiple crevices and sides for traction.
Researchers from the National Institute of Allergy and Infectious Diseases found that COVID-19 can remain active for up to 3 days on plastic and stainless steel surfaces. Another study, appearing in The Lancet Microbe, suggests that coronavirus is “more stable on smooth surfaces”, like hard-surface flooring. These studies suggest that if left untreated, COVID-19 could remain infectious on shoes made from plastics, leather, and synthetic materials for several hours — or even a few days. This is especially true when people walk around in crowded public areas that are more likely to have COVID-19 contamination, such as grocery stores, medical clinics, and public transportation.
Viral transmission vectors can be significantly reduced with only a moderate amount of effort. Hand washing with soap and water for at least 20 seconds is a highly-effective way to reduce viral transmission via hands, but isn’t a reasonable option for shoes. Shoe soles can be treated with the application of a quaternary disinfectant. An easy and effective way to treat shoes at high-traffic entrances is with a sanitizing mat system like Grizzly Sanitize. Sanitizing mats soak shoe soles in disinfectant, allowing the solution to completely contact all parts of the tread and provide an effective method of reducing viral contamination and reducing transmission to other areas.