Covid-19 containment

The pandemic is affecting most areas of everyday life. Vaccinations - at least in Germany - are significantly improving the situation. Nevertheless, further steps are needed to slow down the spread of the disease. We present some of them below.

New technology identifies Covid-19 biomarkers in the shortest possible time [1]

Fig. 2: A textile mask is expertly tested in the laboratory for its separation properties. Faster and cheaper than a standard blood count: researchers at Charité - Universitätsmedizin Berlin and the Francis Crick Institute have further developed mass spectrometry technology so that thousands of proteins in a sample can be measured in just a few minutes. The research team demonstrated the potential of the technology by analyzing blood plasma: using the new technology, they identified eleven previously unknown proteins that indicate the severity of the disease. The study has been published in the journal Nature Biotechnology [2].

Thousands of different proteins are active in the human body at any given time. They give it its structure and enable vital reactions. Even when the body reacts to external influences such as pathogens or medication, it increases or decreases the activity of different proteins. The detailed pattern of proteins in cells or blood samples - the so-called proteome - can therefore help researchers to better understand diseases or make statements about diagnoses and disease progression. Scientists use mass spectrometry to obtain such a "protein fingerprint", but this has been very time-consuming and cost-intensive up to now. The new mass spectrometric technology "Scanning SWATH" now promises a remedy: developed by a team led by Prof. Dr. Markus Ralser, Director of the Institute of Biochemistry at Charité, it is much faster and cheaper than previous methods and allows the measurement of several hundred samples per day.

The potential applications for this high-throughput technology are manifold: from basic research to the large-scale search for effective drugs to the identification of biological characteristics (biomarkers) that can be used to assess the individual risk of patients. In their study, the research group used the example of Covid-19 to show that the technology is suitable for the latter. The team analyzed the blood plasma of 30 patients with varying degrees of Covid-19 symptoms who were treated at Charité and compared the protein patterns with those of 15 healthy individuals. It only took a few minutes to measure a single sample.

In this way, the scientists identified a total of 54 proteins whose concentration in the blood was increased or decreased depending on the severity of the Covid-19 disease. 43 of these had already been linked to the severity of the disease in previous studies; however, this link had not previously been known for eleven of the proteins. Several of these previously unknown proteins are part of the immune system's response to pathogens, which also increases the tendency to clot. "With our new method, we have therefore discovered protein fingerprints in blood samples in a very short time, which we can now use to classify Covid-19 patients according to the severity of their disease," says Dr. Christoph Messner, one of the first authors of the study and a scientist at Charité's Institute of Biochemistry and the Francis Crick Institute. "Such an objective assessment can be very valuable, as patients sometimes overestimate their state of health. However, in order to be able to use mass spectrometric analysis as standard for the classification of Covid-19 sufferers, the technique must be further developed into a diagnostic test. In the future, it may also be possible to use a rapid analysis of the protein pattern to make statements about the probable course of Covid-19. We have already obtained promising initial results in this regard, but further studies are still needed before the test can be used routinely."

Prof. Ralser is convinced that the mass spectrometric examination of blood will complement the classic blood count in the future: "Determining the proteome costs less than a complete blood count. By determining many thousands of proteins simultaneously, a proteome analysis also provides more information. I therefore see great potential in its application, for example for the early detection of diseases. In our studies, we will therefore continue to work towards using proteome technology in this way."

Coated face masks [3]

Textiles for face masks can directly inactivate SARS-CoV-2, as researchers at Freie Universität Berlin and RWTH Aachen University have shown. They can reduce SARS-CoV-2 virus particles by up to 99.9 percent within a few hours.

Researchers at Freie Universität Berlin's Institute of Animal and Environmental Hygiene and the Institute of Textile Technology (ITA) at RWTH Aachen University have investigated innovative textiles for face masks that directly inactivate the Sars-CoV-2 pathogen as part of their research into alternative personal protective equipment. The tests were carried out as part of the European Union-funded EIT health project ViruShield, which aims to find alternative materials for face masks against a backdrop of scarce supply and globally unbalanced supply chains for personal protective equipment. While the researchers from the Institute of Textile Technology (ITA) at RWTH Aachen University investigated the chemical and physical properties of various textiles for face masks, the researchers from Freie Universität Berlin were able to prove that novel textiles developed by the Swiss company Livinguard can reduce high quantities of SARS-CoV-2 virus particles by up to 99.9 percent within a few hours compared to materials commonly used for mask production to date. "The textiles in these masks can thus continuously inactivate the exhaled viruses adhering to the face mask and make the handling of these masks safer overall," explains Professor Dr. Uwe Rösler from the Institute of Animal and Environmental Hygiene at Freie Universität Berlin. "In addition, such textiles could also help to reduce hygiene problems in other general and medical areas, even beyond Covid-19." However, the filtration performance of the masks or mask textiles against aerosols containing viruses was not investigated by the Institute of Animal and Environmental Hygiene as part of the research project.

The SARS-CoV-2 coronavirus can be transmitted by airborne droplets and aerosols. For this reason, governments and health authorities worldwide, as well as the World Health Organization, recommend wearing face masks to protect other people and, to a lesser extent, yourself. Face masks can retain SARS-CoV-2-containing droplets that are produced when exhaling, speaking, coughing and sneezing if the filter performance is sufficient (e.g. medical mouth-nose protection, FFP2/FFP3).

However, great care must be taken when handling contaminated face masks, and after use the masks must either be disposed of or the viruses can be inactivated by washing at higher temperatures or by microwave treatment.

The principle of Livinguard technology is to provide the textile surface with a strong positive charge. When bacteria and viruses come into contact with the technology, the negatively charged microbial cell is destroyed, resulting in the permanent destruction of the pathogens. Unlike alternative metal-based solutions, the novel technology has been proven to be safe for the skin and lungs. In addition, Livinguard technology is highly sustainable and allows users to reuse the mask up to 200 times without compromising safety or effectiveness.

Homemade face masks [4]

Fluffy fabrics such as summer sweat, fleece or nicki, a good fit and several layers of fabric are important for the protective function.

In April 2020, the team led by Frank Drewnick, group leader at the Max Planck Institute for Chemistry, launched a research series spontaneously initiated by the Covid-19 pandemic. In it, they examined a wide variety of everyday materials for their suitability as mouth-nose masks. The continuation of the test series is now providing further insights: The filter effect is largely determined by the tight fit on the face. The number of layers of fabric also has a significant effect on filter performance. With some fluffy materials, the researchers were able to achieve such a good filter effect with several layers of fabric on top of each other that these masks could even protect the wearer. However, the latter would have to be specifically investigated in further tests and was not part of the current research series.

Small leaks greatly reduce filter effect

The results clearly show that even the smallest leaks cause the filtering effect to drop by 50 percent or more. This is particularly true for particles smaller than five micrometers. Leaks of just a few percent of the mask surface area are sufficient to significantly reduce the overall filter effect of the mask. The new measurements also show that layering several layers of fabric can significantly increase the filtering effect of homemade face masks for both small and larger particles without making it difficult to breathe through the mask material. They then filter as well, or even better, than professional surgical masks, for example (see Fig. 3). However, this requires a suitable fluffy fabric that allows air to pass through well, even in several layers.

"If you make a mask with several layers of summer sweat, fleece or Nicki in such a way that it fits tightly to the face everywhere, then particles are caught surprisingly efficiently," says Frank Drewnick, summarizing the latest research findings.

The atmospheric researcher sees a further advantage in the materials that performed well in the tests: they are comparatively cheap and readily available. This means that they can also help to contain the pandemic with homemade masks in regions where the supply of face masks is difficult. The following did well: Summer sweat (French terry), fleece, microfiber cloth (microfiber), felt (felt) and nicki (velour). Drewnick and his team have summarized all their results in a scientific publication that appeared in the journal "Aerosol Science and Technology" [1].

Fig. 3: The figure shows the calculated filtration efficiency for masks with as many layers of material stacked on top of each other (number above each bar) until it is as easy or difficult to breathe through the material stack as through a standard surgical mask. The materials are ordered according to their filtration efficiency, so that (from left to right) the first materials are the most effective at removing particles, while the last are the least effective. This means that all materials that appear before "Surgical Mask1" (14th place) in the graphic separate particles better than the surgical mask with the same "breathability" Source: [5] (CC-By 4.0)

Calculate Covid-19 infection risk yourself [4]

Aerosol particles play an important role in the transmission of Sars-CoV-2 viruses. Aerosols are produced when breathing, coughing or sneezing, but also when talking and singing. Unlike droplets, they do not fall to the ground quickly, but can remain in the air for a long time and spread throughout the room. In indoor spaces where many people are together for long periods of time, the risk of catching the coronavirus via aerosols is therefore particularly high. But how high is the risk of infection really? And how much can it be reduced by wearing a mask, ventilating and keeping your distance? An algorithm can now be used to determine the risk of contracting the SARS-CoV-2 coronavirus from tiny airborne particles in a closed room. It also indicates how the risk is reduced by protective measures such as wearing masks and ventilation. However, it does not allow any statements to be made about the risk of becoming infected through larger droplets if you come into contact with a virus carrier at close range. Rather, the approach can supplement the AHA-L rules. Researchers from the Max Planck Institute for Chemistry and the Cyprus Institute, Cyprus, have now published a study in which they present a simple calculation algorithm to estimate the probability of coronavirus infections from indoor aerosols [6]. The algorithm is based on measurement data on the viral load in aerosols, the amount of airborne particles emitted by people and the behavior of the particles in rooms. The number of viruses contained in aerosols is a major uncertainty, as it can vary greatly between different carriers. The model also specifically determines the risk of infection via the droplets and particles that are so small that they remain in the air for a long time and spread in rooms. It does not allow any statements to be made about the risk of becoming infected via larger droplets that fall quickly to the ground when talking, laughing or singing with carriers of the virus over a short distance.

The risk of infection via aerosols can be calculated using an input mask on the website of the Max Planck Institute for Chemistry. Various parameters such as room size, number of people and length of stay can be entered. Assuming that a person in the room is highly infectious, the algorithm automatically calculates the probability of transmission for the scenarios set by the user. This includes both the individual risk of infection and the risk for any person in the room. You can also choose between different scenarios: a classroom, an office, a party and a choir rehearsal. For experts, there are also fields in which you can vary information such as the infectious dose, the virus concentration of the infected person and the survival time of the virus in the air. The filter efficiency of face masks or the air exchange rate can also be set flexibly.

For example, an adult breathes in and out an average of around 10 liters of air per minute. They also assume that the infectious dose to become infected with Sars-CoV-2 is around 300 viruses or RNA copies per person. The calculation is illustrated using a school classroom in which no safety measures are taken: A 60 square meter, three meter high classroom with 25 students older than ten years and six hours of instruction in which one student is highly infectious for two days. According to the calculation, the probability of a specific person becoming infected under these circumstances is just under 10 percent, while the probability of any other person becoming infected is over 90 percent. Infection is therefore almost unavoidable. An infected person is usually only highly infectious for a few days. Of the people who test positive for the coronavirus, around 20 percent are always highly infectious. They are not to be confused with the so-called superspreaders, of which it is not yet known how frequently they occur. Calculations show that the risk of infection can be reduced by about half through regular ventilation and by a factor of five to ten through additional mask wearing. Using the school class as an example, this means that if the class from the example above ventilates once an hour, the probability is reduced to 60 percent. If all pupils also wear masks, the risk of infection drops to around 24 percent. If you now enter in the input mask that only half of the pupils are attending lessons, the probability of transmission drops to 12%. In the same case, the individual risk drops from ten percent to one percent.

In their publication, the researchers also discuss the uncertainties in the calculations. These lie, for example, in assumptions such as the survival time of the SARS-CoV-2 viruses in the air or the amount of virus that an infected person releases. "Our assumptions are based on the current state of scientific knowledge," says Frank Helleis, physicist at the Max Planck Institute for Chemistry. "There are several variables and assumptions in the calculation. For example, it makes a difference whether and how many people speak and sing in a room, how high the virus concentration in saliva is and what the room air exchange rate is, but each factor is included in the calculation using a simple rule of three," says Helleis, who created the basis for the calculation.

The algorithm is available at: https: //www.mpic.de/4747361/risk-calculator

Literature

[1] Charité - Universitätsmedizin Berlin
[2] Messner, C.B.; Demichev, V;, Bloomfield, N. et al.: Ultra-fast proteomics with Scanning SWATH, Nat Biotechnol (2021), https://doi.org/10.1038/s41587-021-00860-4
[3] FU Berlin
[4] Max Planck Institute for Chemistry
[5] Drewnick, F.; Pikmann, J.; Fachinger,F.; Moormann, L.; Sprang, F.; Borrmann, S.: Aerosol filtration efficiency of household materials for homemade face masks: influence of material properties, particle size, particle electrical charge, face velocity, and leaks, , Aerosol Science and Technology (2020), doi:10.1080/02786826.2020.1817846
[6] Lelieveld, J.; Helleis, F.; Borrmann, S.; Cheng, Y.; Drewnick, F.; Haug, G.; Klimach, T.; Sciare, J.; Su, H.; Pöschl, U.: Model Calculations of Aerosol Transmission and Infection Risk of Covid-19 in Indoor Environments, Int. J. Environ. Res. Public Health (2020), 17, 8114, https://doi.org/10.3390/ijerph17218114