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Infectious Diseases

Updated 01 October 2020

How the coronavirus spreads in a hospital setting

Research presented at a European infectious diseases conference showed how Covid-19 can spread through a hospital via asymptomatic infections and certain hot spots.

  • Research presented at a coronavirus conference highlighted how it can spread in a hospital
  • 40% of infected healthcare workers are asymptomatic, most of them nurses
  • Staff, toilets and public areas in hospitals were found to have high airborne coronavirus positivity rates 

Hospitals understandably have a high rate of coronavirus infections, with increased exposure of healthcare workers. Understanding how Covid-19 might spread in a hospital setting is vital in implementing measures to stop it.

Research presented at the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Conference on Coronavirus Disease this week showed how the virus spreads through a hospital via asymptomatic workers and certain hot spots like toilets and public areas in two presentations.

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Healthcare workers' risk

The first was a meta-analysis of studies in Embase, Pubmed, LILACS, MedxRiv and Google Scholar databases to assess how prevalent the virus is in a hospital, the risk factors for healthcare workers, symptoms and outcomes of severe cases.

It involved 97 studies from across 24 countries with data from over 230 000 healthcare workers. Out of that total, about 10% tested positive for the virus, while 7% had developed antibodies to the disease.

The Swiss researchers found that in 15 of those studies, 40% of healthcare workers that tested positive for Covid-19 were asymptomatic, indicating a high likelihood of silent transmission between colleagues and to patients. 

Almost half who tested positive were nurses, followed by physicians at 25% and other workers at 23%. The most common symptoms were loss of taste and smell, fever and muscle pain.

About one in 20 of those infected developed severe cases of Covid-19, while 0.5% of them died.

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Need for increased testing

"Because we might miss a large proportion of Covid-19 cases if screening targets only symptomatic [healthcare workers], universal screening for all exposed [healthcare workers] regardless of symptoms should be the standard strategy," says study co-author Professor Oscar H. Franco from the University of Bern.

"While more research is needed to understand specific interventions that can help reducing SARS-CoV-2 infection among healthcare personnel, it is clear that providing healthcare workers with adequate personal protective equipment and training is essential."

The same study also found that almost half of the infected staff worked in normal, non-Covid wards, 24% in the operating rooms, 16% in emergency and 9% in ICU. Almost 30% came from other locations.

Weak airborne virus

These other locations were the subject of focus of another study presented at the conference. French researchers reviewed 17 articles to assess potential airborne transmission of the virus in hospital settings, as well as other contamination factors. 

Of 247 total air samples taken around Covid-19 patients' beds, 27.5% were contaminated with the virus, regardless of whether they were in the ICU or not.

The areas in the hospital outside of patients' beds with high positivity rates of the airborne virus particles included public areas at 34.1%, patient toilets at 23.8%, staff areas at 12.4% and clinical areas at 9.5%.

Concentrations of the virus were higher in patients' toilets than by their beds. 

"In hospital, the air near Covid-19 patients is frequently contaminated with SARS-CoV-2 RNA, with, however, poor proof of its infectivity, meaning we detected the viral RNA, but when trying to culture (grow) these samples, there was little evidence of viable virus," the authors add.

"High viral loads found in toilet/bathrooms, staff and public hallways means these areas require strong compliance with cleaning measures and personal protective equipment."

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