Where exactly is the coronavirus lurking?

On my clothes? My shoes? On groceries, on my newspaper, in my hair? The New York Times asked experts where we should—or shouldn’t—suspect the coronavirus to be. We’ve translated their answers for you. After reading this article, you’ll feel better right away.

Does this sound familiar? Now that we’re slowly starting to think about the time after the coronavirus crisis, all sorts of unsettling, everyday questions come to mind. We worry, for instance, about bringing the virus home to our families once we start having more contact with others. So what’s the real situation with viruses on clothing, packages from the mail, or the soles of our shoes?

The New York Times put such reader questions to experts in infectious diseases, aerosols, and microbiology. We found their answers so helpful that we decided to translate them for you and supplement them with the view of a European expert.

Do I need to change my clothes and shower when I get home from shopping?

As long as you follow social distancing guidelines, experts don’t consider this necessary. Washing your hands, on the other hand, is a must and should become an absolute routine. While infectious droplets are released when someone coughs or sneezes, most of them fall to the ground. Studies have detected a few very small particles floating in the air for up to half an hour. Still, it’s highly unlikely that they would land on your clothing.

Dr. Linsey Marr, an aerosol researcher at Virginia Tech, explains: “Droplets small enough to stay airborne will move through the air around the body and clothing.” The reason is aerodynamics: “They follow the airflow around a slowly moving body, just like small insects or dust.” Only at high speeds, such as in a moving car, will some of them hit the windshield.

Every movement we make displaces air, and along these streamlines, particles are pushed away from us as well. For droplets to stop following the streamlines, they would need to be larger and heavier—for example, if someone sneezes or coughs directly at us. Otherwise, you can trust that viral particles simply won’t land on your clothing, due to the laws of physics alone.

Can I have viruses in my hair or beard?

For the reasons outlined above, social distancing should be enough to put your mind at ease here too. Even if someone sneezes or coughs behind you and a particle happens to land in your hair, it’s a fairly unlikely source of infection.

Dr. Andrew Janowski, who teaches infectious disease at Washington University School of Medicine and St. Louis Children’s Hospital, recommends mentally walking through everything that would have to happen for an infection to occur: “First, a certain amount of droplets would have to land somewhere on your hair. Then you’d have to touch that exact part of your hair. Then you’d have to touch your face with that same part of your hand.” At each step, the amount of active viral particles decreases, and in the end, a sufficient concentration must still be present for an infection to occur. The need for such a precise, uninterrupted, and well-timed chain of events ultimately makes infection this way very unlikely.

Is there anything special to consider when doing laundry? Can viral particles be shaken off textiles and spread into the air?

When it comes to laundry, we first need to distinguish between households with and without someone who is ill. You can go on doing your everyday laundry as usual, without worry. Some viruses, like norovirus, are harder to eliminate, but like flu viruses, the novel coronavirus is also surrounded by a fatty membrane that’s destroyed by soap. A regular detergent is completely sufficient to remove it from clothing—if it was even there in the first place. Dr. Marr notes that while it’s been shown that viruses from droplets can settle on clothing and later be shed from it, a truly large amount would be needed to pose an infection risk—far more than you’d pick up during a normal store visit or a walk.

Close contact with one or more sick individuals is a different story. That’s why disease control experts and health authorities unanimously recommend wearing gloves and a face mask when cleaning and tidying up in households with sick people, and avoiding shaking out clothing and bedding whenever possible. When washing, choose the hottest temperature possible. There’s no need to wash the sick person’s laundry separately, nor is a special detergent required. Just make sure everything dries completely. “We know that these viruses die off faster on dry textiles than on metal or plastic,” adds Dr. Marr.

How long does the virus survive on fabric and other surfaces?

In March, the New England Journal of Medicine published a study showing that, under ideal conditions, the virus could be detected for up to 3 days on hard metal and plastic surfaces, and up to 24 hours on cardboard. Textiles weren’t studied, but the cardboard findings offer some clues: on an absorbent, fibrous structure, the virus dries out and dies off faster than on non-absorbent, smooth surfaces. This theory is supported by a 2005 study, which found that another coronavirus (SARS) became non-infectious on paper and cotton cloth after 5 minutes at low concentration, after 3 hours at higher concentration, and after 24 hours at the highest concentration.

Can I get infected from delivery boxes, packages, or the newspaper?

The risk of infection from handling mail, packages, or delivered newspapers is very low and, so far, purely theoretical—there isn’t a single documented case.

That doesn’t mean we should throw caution to the wind, though: disposing of packaging and then washing your hands is a sensible approach, and anyone who wants to take extra precautions can follow the New England Journal study’s lead and leave packages untouched for 24 hours first.

How risky are outdoor activities or walking the dog?

Very low, as long as you maintain social distancing.

“It’s safe outside—there definitely aren’t clouds of high viral load just floating around out there,” says Professor Lidia Morawska, head of the International Laboratory for Air Quality and Health at Queensland University of Technology in Brisbane, Australia. “All infectious exhaled droplets dissipate quickly outdoors,” explains Dr. Morawska, adding that the virus remains stable for a much shorter time outside than indoors. So there’s no reason to worry about jogging or other outdoor activities, except in larger crowds—which aren’t allowed at the moment anyway.

What about my shoes? Should I disinfect them when I get home?

Shoes can harbor all sorts of bacteria and viruses. Even so, they’re a fairly unlikely source of infection. In 2008, Rockport Shoes conducted a study and found all kinds of nasty things on shoe soles, including E. coli. In China, researchers examined the shoes of healthcare workers and found coronavirus on half of them—hardly surprising, since they were caring for infected patients.

So what should you do with your shoes? Washable sneakers can simply be washed. However, it’s best not to wipe disinfectant wipes over the soles, since doing so can transfer germs from a surface you wouldn’t normally touch directly onto your fingers.

Have you ever considered a shoe-free household? Leave your outdoor shoes near the entrance and avoid wearing them into your living spaces. Parents with crawling-age children will especially thank you for it. When it comes to the coronavirus, Dr. Janowski says shoes aren’t a major source of concern. Still, it’s hard not to feel a bit squeamish thinking about everywhere they’ve been and everything they might be carrying.

Maybe it’s not such a bad idea for general hygiene after all: outdoor shoes only as far as the entrance. The Japanese tradition of a strictly shoe-free household has been growing on us lately.

That’s what the New York Times has to say. But is there a European perspective on this? We asked Univ. Prof. Dr. Heribert Insam, head of the Institute of Microbiology at the University of Innsbruck. He considers all of these measures sensible. However, he warns against excessive use of disinfectants, explaining: “The microbiota—the many bacteria living in our pores and on our skin—form our first line of defense against pathogens. They secrete virucidal substances, meaning substances that kill viruses. That’s why it’s better to wash your hands with regular soap, so as not to destroy our natural barrier with too much disinfectant.”

Sources: The New York Times, April 17, 2020;
Univ.-Prof. Dr. Heribert Insam, Institute of Microbiology, University of Innsbruck