Current studies from England are showing that the risk of being infected with SARS-CoV-2 is high in healthcare facilities. One of the studies shows that the mortality rate of COVID-19 patients who become infected in hospital is lower than in patients admitted to hospital who had already contracted COVID-19.

According to the National Health Service England (NHS), currently 17.6% of COVID-19 infections in England are most likely due to infection in healthcare facilities. In the North West of England the rate is up to 25% and it is rising further in other parts of the country. Healthcare-associated COVID-19 infection in hospitals is defined by the NHS as being present when the diagnosis is made 7 days after admission. [1]

These figures are supported by a study conducted by King’s College London. According to the survey, at least 12.5% of COVID-19 hospital patients became infected with the coronavirus during their stay in hospital. The majority of the affected patients had been in hospital for a long time already. In the study, an infection was defined as acquired in hospital if it occurred 15 days after patient was admitted. [2]

Importance of timely clinical treatment

The King’s College study also compared the treatment outcomes of COVID-19 patients infected outside of hospital with those who had contracted the infection in hospital. The result: Taking into account age, pre-existing health conditions and the severity of the infection, those who became infected in hospital were less likely to die than comparable patients who became infected outside of hospital. [2]

The researchers suspect that the better outcomes for patients infected with coronavirus in hospital can be attributed to closer monitoring, faster diagnosis and timely clinical treatment. According to experts, the results also suggested that patients who became infected in hospital recovered better than patients who had already been hospitalized with a COVID-19 infection due to the rapid clinical treatment they received. [2]

Sources:

1.Heneghan C, Howdon D, Oke J, Jefferson T The Ongoing Problem of UK Hospital Acquired Infections
October 30, 2020, https://www.cebm.net/covid-19/the-ongoing-problem-of-hospital-acquired-infections-across-the-uk/ (Letzter Zugriff am 03.11.2020).

2. Carter et al. (2020) Nosocomial COVID-19 infection: examining the risk of mortality. The COPE-Nosocomial study (COVID in Older People). Journal of Hospital Infection. DOI: 10.1016/j.jhin.2020.07.013.

The number of staff suffering from a COVID-19 infection during their nursing or medical work is on the rise. Almost 10,000 cases (situation report dated 05/03/2020) were recently recorded by the Robert Koch Institute with a high estimated number of unreported cases. A current retrospective cohort study at the University Hospital in Wuhan with 3,300 beds provides information about the specific risks for health workers.

The most important risk factors of COVID-19 infection in staff:

• Working in a high risk department

• Working shifts of more than 10 hours

• Lack of hand hygiene compliance before and after contact with patients

• Insufficient personal protective equipment

The development of the pneumonia pandemic COVID-19, caused by SARS-Cov-2, remains a cause for concern. More and more healthcare workers are among those infected. Communicable respiratory diseases are considered to be a particular risk for nurses and physicians. During the SARS outbreak in 2002, approximately 1,725 healthcare workers were infected with Severe Acute Respiratory Syndrome (SARS) while caring for patients who had contracted SARS.

For this reason, greater importance should be placed on the protection of health workers. In order to better understand how staff can be protected, a research team at a 3,300-bed clinic responsible for the medical treatment of COVID-19 patients carried out a retrospective cohort study of 72 health workers. All study participants were suffering from an infection of the respiratory tract or showed typical symptoms.

Participants from different departments were divided into two groups for the study based on their risk exposure:

• High-risk department

This included staff working in the intensive care unit, the infection ward or the surgical ward or performing activities that generated respiratory aerosols.

• General groups

This included staff from all other departments where a low risk of infection was assumed.

A follow-up observation confirmed COVID-19 infection in 39% of the participants. Staff were asked to fill out an online questionnaire, which contained detailed information on socio-demographic characteristics, symptoms and course of illness, contact history, occupation, working hours, hand hygiene and the wearing of personal protective equipment (PPE). A total of 72 questionnaires were valid and were included in order to analyze the risk factors. Of these 72 individuals, 39 were assigned to the general low-risk department and 33 to the high-risk department.

Staff from the high-risk department had a risk of developing COVID-19 that was 2.13 times higher compared to the general department group. The higher the number of daily working hours, the higher the risk was that staff would fall ill with COVID-19. This scenario applied to the high-risk department in particular. The researchers assumed that all of the staff there would have been infected if they had had to work 15 hours a day.

According to the authors, the four most important risk factors of COVID-19 infection in staff are working in a high-risk department, working shifts of more than 10 hours, a lack of hand hygiene compliance before and after contact with patients and inadequate personal protective equipment.

Sources:
Ran L, Chen X, Wang Y, Wu W, Zhang L, Tan X. Risk factors of healthcare workers with corona virus disease 2019: a retrospective cohort study in a designated hospital of Wuhan in China. Clin Infect Dis. 2020 Mar 17 [Epub ahead of print]. https://doi.org/10.1093/cid/ciaa287 Last accessed 5/3/2020

The airborne transmission of SARS-CoV-2 could play a greater role than previously assumed. A research team from America, together with several cooperating laboratories, found out that the virus particles in aerosols remain viable in the air for up to 16 hours.

A research team from America led by Dr. Chad Roy and Dr. Alyssa Fears from Tulane University in New Orleans, together with cooperating laboratories, has measured the potential of SARS-CoV-2 as an airborne virus and compared it with that of other known coronaviruses, namely SARS-CoV (2002) and Middle Eastern Respiratory Syndrome CoV (MERS-CoV; from 2012). Additionally, the experts investigated how long the viruses can maintain their infectivity when distributed in aerosols.

Potential for airborne transmission

For their investigations, the researchers used jet atomizers to produce viral aerosols. Comparative experiments were conducted in four separate aerobiology laboratories. The aerosols were generated in exposure chambers. Generators distributed the aerosols in orders of magnitude from 1–3 μm, meaning they are respirable particle sizes. Inside the chambers, aerosols were exposed to a total flow of half to one air exchange per minute – depending on the test laboratory.

No change to structure

By using the chambers and the corresponding flow rates, the research team was able to determine the dynamic potential for airborne transmission. Aerosol samples were collected during the initiation of the aerosols into the chamber by the atomizers and continuously for 10–30 minutes. To determine the aerosol efficiency, the researchers defined a so-called spray factor. The spray factor is the result of two values: The initial titer, which determines the number of viruses in the respective liter dispensed via the atomizer (PFU (plaque forming units)/liter in liquid supply) and the number of viruses in the aerosol (PFU/litre aerosol). Both values form the quantitative indicator with which the potential for airborne transmission of the viruses was assessed.

Further studies with SARS-CoV-2 in one of the cooperating laboratories determined the long-term stability of the airborne virus. A rotating (Goldberg) drum was used to create an environment in which the settling speed of the 2–3 μm particles is overcome by the rotational speed of the drum. This produces a static aerosol suspension (aerosol suspension stability experiment). The collected aerosol samples were subjected to various methods to determine the concentration of infectious virus particles (cell culture, RNA determination) The scanning electron microscope was also used to investigate whether the structure of the virus in the aerosol suspension changed.

High stability confirmed in all experiments

Measured by the so-called spray factor, SARS-CoV-2 showed the highest concentration of virus particles compared to SARS-CoV and MERS-CoV. The aerosol suspension stability experiment showed that SARS-Cov-2 maintained its ability to replicate and therefore retained its infectivity at all times – even when sampling was performed at 16 hours aerosol suspension. Using scanning electron microscopy, the researchers were also able to show that the airborne SARS-CoV-2 maintained its structure as well as its size and aspect ratios for up to 16 hours. This means that after 16 hours and 10 minutes, the virus particles still resembled the shape and structure of the virus particles examined before aerosol generation, which leads the research team to conclude that infectivity is still present.

According to the scientists, these data suggest that SARS-CoV-2 generally retains infectivity during airborne transmission over short distances and that this novel coronavirus is more viable over longer periods of time than would be expected when produced as a highly respirable particle (2 μm).

Some of the aerosols naturally produced by coughing and breathing fall within the size distribution used in the experimental studies carried out by the American scientists (<5 μm). The authors conclude that individuals infected with SARS-CoV-2 have the ability to produce viral bioaerosols that can remain infectious over long periods after produced through human excretion and airborne transport.

Source
4. Fears AC et al. Comparative dynamic aerosol efficiencies of three emergent coronaviruses and the unusual persistence of SARS-CoV-2 in aerosol suspensions. medRxiv preprint doi: doi: https://doi.org/10.1101/2020.04.13.20063784