A new study from the Centers for Disease Control and Prevention (CDC) not only suggests that COVID-19 may travel on shoes, but that airborne transmission of the virus may pose risks, too.

By Faith Brar
April 15, 2020
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Your coronavirus prevention practices are probably second-nature at this point: wash your hands frequently, disinfect your personal space (including your groceries and takeout), practice social distancing. But if you've wondered whether coronavirus can travel on your shoes—and, if it can, whether that means shoes in the house are a huge no-no—a new study may shed some light.

Refresher: As of now, the main (read: not the only) routes of coronavirus transmission are said to be respiratory droplets that travel via coughing and sneezing and direct physical contact with someone who has the virus (even if they're not experiencing obvious coronavirus symptoms). The virus can also live on certain surfaces, though there are conflicting reports about how long the virus can live outside the human body and whether this form of coronavirus transmission is all that common.

To find out more, researchers in Wuhan, China tested several air and surface samples in the intensive care unit (ICU) and a general COVID-19 ward at Huoshenshan Hospital. Between February 19 and March 2, researchers collected surface swab samples from potentially contaminated objects like floors, computer mice, trash cans, hospital bed handrails, patients' face masks, healthcare workers' personal protective equipment (PPE), as well as indoor air and air vent samples. Perhaps unsurprisingly, the results, published in the Centers for Disease Control and Prevention (CDC)'s journal, Emerging Infectious Diseases, showed that many of these samples tested positive for COVID-19—but floors appeared to be a particularly common, somewhat unexpected hotspot.

To break it down further, 70 percent of the floor samples taken from the hospital's ICU tested positive for COVID-19, compared to about 15 percent of the general COVID-19 ward floor samples, according to the study's results. Researchers theorized in their paper that this was likely due to "gravity and airflow" that caused virus droplets to float to the ground. They also noted that the high number of COVID-19-positive floor samples made sense since workers in both areas were treating patients with the coronavirus.

Again, it's probably not surprising that commonly touched surfaces—let alone those in hospital settings—like computer mice, hospital bed handrails, and face masks were often found to be COVID-19-positive in the study. But what really took researchers by surprise was that 100 percent of floor swab samples from the hospital's pharmacy—where there were no patients at all, according to the study—tested positive for COVID-19. Meaning, it's likely that the virus "tracked all over the floor" of the hospital building, or at least wherever hospital workers treating patients with COVID-19 were walking (assuming the workers wore the same shoes the whole time), the researchers wrote in their study. "Furthermore, half of the samples from the soles of the ICU medical staff shoes tested positive," the study authors wrote. "Therefore, the soles of medical staff shoes might function as carriers." Based on these findings, the researchers recommend that people disinfect their shoe soles before walking out of areas with people who have COVID-19. (Related: Is That Simulation of Runners Spreading Coronavirus Actually Legit?)

Surfaces aside, 35 percent of the ICU indoor air samples and roughly 67 percent of ICU air vent samples tested positive for COVID-19, according to the study's results. Samples taken from the general COVID-19 ward seemed less likely to test positive, with 12.5 percent of air samples and 8.3 percent of air vent swabs showing traces of the virus. "These results confirm that SARS-CoV-2 [the virus that causes COVID-19] aerosol exposure poses risks," reads the paper. But FTR: In general, experts can't seem to agree on just how risky airborne transmission of the virus is, particularly in comparison to other evidence-based routes of coronavirus transmission. For now, the World Health Organization (WHO) says there isn't enough evidence to confirm that COVID-19 is airborne. (Related: The 7 Best Air Purifiers to Keep Your Home Clean)

How worried should you be about whether coronavirus travels on your shoes?

First of all, it's important to reiterate that this new study was conducted in a hospital that was treating a high number of COVID-19-positive patients. "Hospitals, especially ICUs, have a much higher density of the virus compared to other places, so it's not an exact correlation to the outside world," says Purvi Parikh, M.D., a pediatric allergist, immunologist and member at the Physicians for Patient Protection of the study's results. (Related: What an ER Doc Wants You to Know About Going to a Hospital for Coronavirus RN)

That said, the study does demonstrate just how easily the virus can spread, not to mention how much new information researchers are learning every single day about the coronavirus—which is why taking certain precautions just to be safe (yes, like not wearing shoes in the house) really isn't a bad idea, explains Dr. Parikh.

Plus, research on the transmission of other types of coronaviruses suggests these pathogens may live on a number of surfaces—including cardboard, plastic, and metal, among others—for anywhere between two and nine days, says Mary E. Schmidt, M.D., M.P.H., a board-certified infectious disease specialist. Based on those findings, "there's a chance the [novel] coronavirus can live in or on shoes" (particularly shoe soles, she notes) for hours or days at a time; it's simply too early to know for sure, she explains.

But as of now, the likelihood of you dragging COVID-19 into your home from grocery stores or outdoor streets and sidewalks is low, says Dr. Schmidt. Still, if you want to err on the safe side, she recommends not wearing shoes at home and taking the following precautions:

  • Be cautious while removing your shoes. If you're physically able to do so, try not to touch your shoes at all when taking them off, suggests Dr. Schmidt. "You're more likely to contaminate your hands or clothing when you touch them or try to wipe them down," she explains. Of course, in many cases that's easier said than done—so, either way, make sure you immediately wash your hands after sliding the shoes off your feet, she adds.
  • Clean your shoes regularly. To clean your shoes, spray the top and bottom with a CDC-approved coronavirus cleaning product, let the disinfectant sit for about a minute, then wipe down and immediately wash your hands, says Dr. Schmidt. For shoes that can go in the washing machine, wash them frequently using high heat, which may further help to kill traces of the coronavirus, she says. (Related: Does Vinegar Kill Viruses?)
  • Have designated indoor and outdoor shoes. Or, again, consider not wearing shoes at all in the house. Either way, Dr. Schmidt recommends sticking to only one or two pairs of shoes in general. "Put the shoes on paper and remember to clean the floor under the shoes as needed," she adds.

The information in this story is accurate as of press time. As updates about coronavirus COVID-19 continue to evolve, it’s possible that some information and recommendations in this story have changed since initial publication. We encourage you to check in regularly with resources such as the CDC, the WHO, and your local public health department for the most up-to-date data and recommendations.

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