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Coronavirus on Surfaces: What's the Real Risk?

photo of person spraying counter

Sept. 3, 2020 -- In March, concerns over the coronavirus surviving on surfaces fueled a disinfectant shopping frenzy that left store shelves bare of hand sanitizer and cleaning wipes. A video featuring a Michigan doctor sanitizing his groceries one by one captured more than 26 million views on YouTube.

With no signs of the coronavirus pandemic letting up, protecting yourself from germs is as important as ever. But we now know that the virus that causes COVID-19 mainly spreads through respiratory droplets in the air. So can you really catch COVID-19 from touching a cereal box you bought at the supermarket, or a package delivered to your door?

It is theoretically possible, but highly unlikely, says Dean Blumberg, MD, chief of pediatric infectious diseases at UC Davis Children's Hospital. "You'd need a unique sequence of events," he says. First, someone would need to get a large enough amount of the virus on a surface to cause infection. Then, the virus would need to survive long enough for you to touch that surface and get some on your hands. Then, without washing your hands, you'd have to touch your eyes, nose, or mouth.

Coronavirus on Surfaces

Researchers have found that the coronavirus can stay alive on surfaces. A New England Journal of Medicine (NEJM) study from April showed that the new coronavirus can survive on plastic and stainless steel for up to 3 days, and on cardboard for up to 1 day. Another study from China found that the virus can travel on the soles of shoes.

But the results of studies like this one have led some people to exaggerate the risk of COVID-19 transmission, says Emanuel Goldman, PhD, a professor of microbiology, biochemistry, and molecular genetics at the New Jersey Medical School of Rutgers University. In a response published in The Lancet Infectious Diseases this past May, he wrote that the NEJM study used much higher concentrations of the virus than people would find in the real world.

"In my opinion, the chance of transmission through inanimate surfaces is very small, and only in instances where an infected person coughs or sneezes on the surface, and someone else touches that surface soon after the cough or sneeze (within 1-2 hours)," Goldman wrote. Basically, it would take the perfect combination of events Blumberg described to get sick from touching something contaminated with the virus.

Also, studies have only proved that the virus stays alive on surfaces -- not that you can catch it from touching those surfaces. "They don't prove that just because it can survive on a surface, it can be transmitted that way," Blumberg says.

In late May, the CDC updated its website to say it's possible, but unlikely, for people to catch the virus this way. Surface transmission may have played a role in two cases.??A recent study from China documented possible transmission through an elevator button, and another study of cases in a South African hospital found that contaminated medical equipment may have helped spread the virus.

The Right Way to Protect Yourself From COVID-19

Alicia Kraay is an infectious disease epidemiologist at Emory University who is studying how much cleaning and disinfection impacts the risk of getting COVID-19.

She believes that hard surfaces may play a role in transmission of the infection, especially if they’re in a common area.?She recommends that those should be cleaned regularly.

But If you are trying to do things that cut your overall risk of catching COVID, obsessively wiping down every surface around you isn’t going to be very protective if it’s the only thing you’re doing.??Cleaning surfaces does help if you’re doing other things, too, like wearing a mask, social distancing and washing your hands regularly. It’s another layer of safety.

Blumberg says?if you put too much of your focus on disinfecting surfaces, you could miss the real COVID risks. "I find that all these contact concerns distract people from doing things that are proven to prevent transmission, like wearing a mask and social distancing," Blumberg says.

People who spray everything in sight with bleach and other harsh cleaners should also know that disinfectants can have risks, too. For one thing, they can irritate the lungs and worsen symptoms in people who have asthma.

These products can also irritate your skin if you don't use them carefully. "For many of these disinfectants, you should really be wearing gloves," Blumberg says.

Wearing a mask when you're around other people is a proven protection strategy that can cut your risk of catching COVID-19 by about 65%. Putting at least 6 feet between you and the nearest person will also keep the coronavirus at a safe distance.

Blumberg says it's still a good idea to wash your hands with soap and water. Hand-washing is especially important after you've been out in public or used the bathroom, and before you eat. Though you can't catch COVID through food, there's a slight chance you could get it from the germy hands that carry that food into your mouth.

Keep your surroundings clean, but don't go overboard with the disinfecting. "I don't think the benefits are worth the effort," Blumberg says.

WebMD senior health news writer Brenda Goodman contributed to this article.?

WebMD Health News Reviewed by Michael W. Smith, MD on September 03, 2020

Sources

Dean Blumberg, chief of pediatric infectious diseases, UC Davis Children's Hospital.

CDC: "CDC updates COVID-19 transmission webpage to clarify information about types of spread," "Food and Coronavirus Disease 2019 (COVID-19)," "Frequently Asked Questions," "How COVID-19 Spreads," "How to Protect Yourself and Others."

European Respiratory Journal: "Occupational exposure to disinfectants and asthma control in U.S. nurses."

The New England Journal of Medicine: "Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1."

The Lancet: "Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis."

The Lancet Infectious Diseases: "Exaggerated risk of transmission of COVID-19 by fomites."

UC Davis: "Your Mask Cuts Your Own Risk by 65 Percent."

The Washington Post: "Long lines, low supplies: Coronavirus chaos sends shoppers into panic-buying mode."

YouTube: "PSA Grocery Shopping Tips in COVID-19," Jeffrey VanWingen.

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