Healthcare workers can carry coronavirus particles on their shoes, new CDC research shows

Fan Zhongjie, a respiratory doctor in charge of about 30 critical COVID-19 patients in a Wuhan, Chin hospital, writes encouraging words for a patient on February 25, 2020. Feature China/Barcroft Media via Getty Images

The new coronavirus causes a respiratory illness, so it typically spreads via airborne droplets. When an infected person coughs or sneezes, droplets carrying viral particles can land on someone else’s nose or mouth or get inhaled.

But a person can also get the coronavirus if they touch a surface or object that has viral particles on it and then touch their mouth, nose, or eyes. The virus can survive for a time on surfaces – between three hours and seven days, depending on the material.

Recent research suggests objects in hospitals are highly contaminated, putting healthcare workers at disproportionate risk of infection.

A new CDC study found that particles of the coronavirus, which has the scientific name SARS-CoV-2, were “widely distributed in the air and on object surfaces” in the intensive-care unit and general ward of the Huoshenshan Hospital in Wuhan, China.

The “virus was widely distributed on floors, computer mice, trash cans, and sickbed handrails” in the hospital’s general COVID-19 ward and intensive care unit (ICU), the researchers found.

What’s more, the study authors discovered that 50% of the samples taken from shoe soles of the ICU medical staff tested positive, suggesting that shoes “might function as carriers” of the coronavirus in a hospital setting.

The virus may be scattered throughout hospitals on shoes

A group of Chinese healthcare workers who wear protective coverings over their shoes. Feature China/Barcroft Media/Getty Images

The study authors collected samples between February 19 and March 2 from potentially contaminated objects in Huoshenshan Hospital’s ICU and general ward, which housed 15 and 24 COVID-19 patients, respectively.

They found that objects and the floor in the ICU were more likely to test positive than those in the general ward – 43.5% of samples from the ICU had live virus, compared to 7.9% of objects in the ward.

The virus was most often found on computer mice, followed by trash cans and sickbed handrails.

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Seven out of 10 samples taken from the ICU floor tested positive, “perhaps because of gravity and air flow causing most virus droplets to float to the ground,” the authors wrote. Live virus was also found in every sample taken from the floor in the hospital’s pharmacy (where there were never any patients), suggesting that medical staff may have been tracking viral particles between different sections of the hospital.

However, just because live virus was present in these samples doesn’t mean that there were enough viral particles on those surfaces to cause an infection if touched and transferred to a healthcare worker’s mouth or nose.

Positive samples “do not indicate the amount of viable virus,” the researchers noted.

The study also found that the coronavirus could travel up to 13 feet in the air

The study authors also found that the virus could travel in the air as aerosols – clouds of tiny viral particles – in the hospital.

They identified live coronavirus in 35% of samples taken from the air in the ICU, and in 12.5% of the samples taken from the air in the general ward.

By tracking the virus’ spread in the air throughout the hospital, the researchers concluded that particles could travel up to 13 feet (4 meters) as aerosols.

However, they noted that the transmission distance for infectious aerosols “cannot be strictly determined” because experts don’t know how many viral particles are needed to actually sicken someone.

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The study revealed that coronavirus aerosols were most concentrated in patients’ rooms, particularly near and downwind from them.

However, despite “environmental contamination” in the hospital’s ICU and general ward, the study authors noted that, as of March 30, no staff members at Huoshenshan Hospital had been infected with SARS-CoV-2.

This indicates “that appropriate precautions could effectively prevent infection,” they wrote.

The researchers recommended that healthcare workers disinfect their shoe soles before walking out of wards where they have treated COVID-19 patients.