Where lurks the virus?

On my clothes? My shoes? On purchased goods, my newspaper, my hair? The New York Times asked experts about where we have to suspect the Coronavirus lurking (or not). We compiled their answers slightly shortened and with a comment of a European expert. You will feel better after reading this.

Does this sound familiar? Now that we start thinking about the time after the Corona crisis, we are asking ourselves all kinds of unsettling questions of a very everyday nature. For example, we fear that the virus will be introduced into the family environment as soon as we have more contact with others. What about viruses on clothing, delivery boxes, packaging, your mail or the soles of shoes?

The New York Times has passed such questions from their readers to experts in infectious diseases, aerosols and microbiology. We found the answers so helpful that we compiled  them and would like to pass them on to you with the opinion of an European expert.

Should I change my clothes and shower when I get home from the grocery store?

If the rules of social distancing are followed, the experts do not consider this necessary. Washing hands, however, is mandatory and should absolutely be part of your daily routine. Infectious droplets fly as soon as someone coughs or sneezes, but they mostly land on the ground. Studies were able to detect isolated, very small particles floating in the air for up to half an hour. However, they are very unlikely to end up on clothing.

At Virginia Tech, Dr. Linsey Marr researches aerosols. She explains, "Droplets small enough to float will move around the body and clothing in the air." The reason for this is aerodynamics: "They follow the air flow around a body that moves slowly, like small insects or dust." Only at high speeds, for example in a car, some of them will be slammed against the windshield.

With every movement we displace air creating a flow around our bodies. Along these streamlines particles are pushed away from us. The droplets would have to be bigger and heavier to stop following the streamlines, such as when someone sneezes or coughs directly at us. Otherwise you can trust that virus particles do not end up on our clothing - simply due to physical laws.

Can viruses be in my hair or beard?

For the reasons given above, social distancing should be sufficient to be safe in this regard. And even if someone sneezes or coughs behind us and a particle lands on their hair, it's a pretty unlikely source of infection.

Dr. Andrew Janowski teaches pediatric infectious diseases at the Washington University School of Medicine and St. Louis Children's’s Hospital. He recommends that you mentally  go through all the steps that need to happen until somebody gets infected: “First, a certain amount of droplets has to land somewhere on your hair. Then you have to touch exactly this part of your hair. Then you have to touch your face with the same area of ​​your hand.” With each step, the amount of transmitted active viral particles decreases, and at the end there must be enough for an infection. The required, closed and timely sequence of so many events until infection makes it pretty unlikely to happen.

Do I have to pay special attention to the laundry? Can I shake loose viral particles from textiles and send them into the air?

It makes a difference whether you are doing your regular household laundry or cleaning up after a sick person. You can take care of everyday laundry as usual. Some viruses, such as the norovirus, are more difficult to eradicate, but like the flu virus, the new type of corona virus is surrounded by a fatty membrane that is vulnerable to soap. A normal detergent is completely sufficient to remove it from clothing - if it was present at all. Dr. Marr says: “We do know that viruses can deposit on clothing (from droplets) and then be shaken loose into the air with movement, but you would need a lot of viruses for this to be a concern, far more than a typical person would encounter while going for a walk outdoors or going to a grocery store”.

The exception is if you are in close contact with a sick person. It is recommended to wear gloves when cleaning up after someone who is sick, and take care not to shake laundry and bedding. Use the warmest water setting possible and dry completely. You can mix laundry from an ill person with the rest of the household load. But just leaving laundry to sit for a while also reduces risk, because the virus will dry out and decay. “We know these types of viruses tend to decay faster on fabric than on hard, solid surfaces like steel or plastic,” said Dr. Marr.

How long can the virus remain viable on textile and other surfaces?

An important study published by The New England Journal of Medicine in March found that the virus can survive, under ideal conditions, up to three days on hard metal surfaces and plastic and up to 24 hours on cardboard. It did not look at fabric, but most virus experts believe it offers clues about how the virus probably behaves on fabric. The absorbent, natural fibers in the cardboard appeared to cause the virus to dry up more quickly than it does on hard surfaces. The fibers in fabric would be likely to produce a similar effect.

A 2005 study of the virus that causes SARS, another coronavirus, provides further reassurance. Researchers tested increasingly large amounts of viral samples on paper and cotton. Depending on the concentration of the virus, it took five minutes, three hours or 24 hours for it to become inactive.

Should I be concerned about delivery boxes, mail or newspapers?

The risk of getting sick from handling mail or packages is extremely low and, at this point, only theoretical. There are no documented cases so far.

But that doesn’t mean you shouldn’t take precautions. After handling mail or packages or reading the newspaper, dispose of the packaging and wash your hands. If you still feel especially anxious about it, take guidance from the New England Journal study and just let mail and packages sit for 24 hours before handling them.

What about contamination risk if I go outside to exercise or walk the dog?

Your chances of catching the virus when you go outdoors is extremely low, provided you’re keeping a safe distance from others.

Outdoors is safe, and there is certainly no cloud of virus-laden droplets hanging around,” said Lidia Morawska, professor and director of the International Laboratory for Air Quality and Health at Queensland University of Technology in Brisbane, Australia.

In addition, the stability of the virus outside is significantly shorter than inside. So outside is not really a problem, unless if we are in a very crowded place — which is not allowed now anyway”.

What about my shoes? Should I wipe them down with disinfectant after coming home?

Shoes can harbor bacteria and viruses, but that doesn’t mean they are a common source of infection. A 2008 study commissioned by Rockport Shoes found a lot of gross stuff, including fecal bacteria, on the soles of our shoes. A recent study from China found that among health care workers, half had coronavirus detected on their shoes, which is not unexpected since they worked in hospitals with infected patients.

So what to do about? If your shoes are washable, you can launder them. Cleaning the soles with disinfectant wipes is not recommended. It could only bring germs from a surface you normally wouldn’t touch directly to your hands.

You can try not to think about what’s lurking on your shoes — or maybe consider a shoe-free household. Take off your shoes when you get home, store them near the entrance and do not enter living spaces with them. Parents with babies in the crawling phase will love that habit. Dr. Janowski says shoes are not a big worry for contracting coronavirus. But that Japanese tradition of the shoe-free home might be a good idea for general hygiene. “We know bacteria love to live on shoes,” Dr. Janowski adds. “You never know what you stepped in.”

So that's what the New York Times writes. Is there a European opinion on this? We have asked Univ. Prof. Dr. Heribert Insam, head of the Institute of Microbiology at the University of Innsbruck. He agrees and thinks that all of the described measures make sense. On the other hand, he warns against the excessive use of disinfectants and explains: “The microbiota, that is the many bacteria that live in the pores and on the skin, form our first line of defense against pathogens. They excrete virucidal, that is, virus-killing substances. It is better to wash your hands with conventional soap so as not to kill our natural barrier with too much disinfectant.

Source: The New York Times, 17. 4. 2020;
Univ.-Prof. Dr. Heribert Insam, Institute of Microbiology at the University of Innsbruck

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