People still have many questions about the coronavirus. One that has crossed my desk often in the past week or so is, “can you track COVID-19 into your house from the outside on your shoes?”
The answer is: Maybe, but, probably not.
Despite recent evidence that suggests that the COVID-19 virus can live on surfaces for days longer than the experts at first thought, public health specialist Carol Winner said to keep in mind that there is no proof right now that coronavirus comes into the house on shoes.
This makes it important to follow the Centers for Disease Control and Prevention’s recommendations to wash your hands thoroughly (at least 20 seconds), work from home if you can and avoid touching your face.
“There is no evidence to say that the coronavirus comes into the house from shoes,” she told the press. “Pragmatically, they are on the body part furthest from our face, and we do know that the greatest risk of transmission is person to person, not shoe to person.”
Although the CDC now knows that the coronavirus, is thought to be spread person-to-person through respiratory droplets, there is evidence the virus is able to live on surfaces.
A study published by the National Institutes of Health, for example, showed that the virus can live on cardboard for 24 hours and for two to three days on stainless steel and plastic.
However, shoes can be a potential source of contamination, according to family practitioner Georgine Nanos, especially if they’re worn in heavily populated areas (in grocery stores, on mass transit, etc.) and in workplaces.
“As of today, we believe coronavirus can live on surfaces for up to 12 hours, potentially longer,” Nanos said. “And this definitely includes shoes.”
Infectious disease specialist Mary E. Schmidt said the time can actually be five days or more, this according to studies done on materials closely related to shoe materials at room temperature.
Respiratory droplets containing coronavirus can certainly land on footwear, according to Winner, who explained that some synthetic materials, such as spandex, can allow the virus to remain viable for a few days.
Shoes made with plastics and synthetic materials can carry an active virus for days, but she noted that more research is needed.
“We’ve learned from the National Institute of Allergy and Infectious Diseases that coronavirus can remain active on some surfaces, like plastic, for up to two to three days,” Winner said. “This suggests that viruses deposited on shoes made of plastic could retain the active virus for a few days,” and they could dry out sooner on natural fibers.
However, whether you wear sneakers or work boots, emergency physician Cwanza Pinckney stressed, it’s important to pay attention to the sole.
“The sole of the shoe is the breeding ground of more bacteria and fungi and viruses than the upper part of a shoe,” Pinckney explained.
Soles are typically made of non-porous materials, such as rubber, leather and PVC compounds, and can carry high levels of bacteria, according to a study published by Charles Gerba, a microbiologist and professor at the University of Arizona.
The 2008 study indicated that the average shoe sole is covered with 421,000 bacteria, viruses and parasites. But Pinckney suggested not stressing over this figure too much: Those hitchhikers can also allow humans to develop immunity to the pathogens over time.
When it comes time to clean your work shoes, Pinckney advised wiping them down with disinfecting cloths frequently.
Additionally, she recommended washing your shoes if they are machine washable or cleaning them with hot water and soap if you have nothing else in the house.
“Wiping down your shoes is probably most effective when using an alcohol-based wipe,” she said. “You can also wash your shoes on a short cycle in the washing machine, and use hot soap and water if you don’t have anything else to use.”
Winner also suggested Lysol can be used to inactivate viruses that adhere to your shoes but warned against using it on shoes made with natural materials. It can damage the finish of your shoe, she added.