Modeling and simulation of infectious diseases: Microscale transmission, decontamination and macroscale propagation

The COVID-19 pandemic that started in 2019-2020 has led to a gigantic increase in modeling and simulation of infectious diseases. There are numerous topics associated with this epoch-changing event, such as (a) disease propagation, (b) transmission, (c) decontamination, and (d) vaccines. This is an evolving field. The targeted objective of this book is to expose researchers to key topics in this area, in a very concise manner. The topics selected for discussion have evolved with the progression of the pandemic. Beyond the introductory chapter on basic mathematics, optimization, and machine learning, the book covers four themes in modeling and simulation infectious diseases, specifically: Part 1: Macroscale disease propagation, Part 2: Microscale disease transmission and ventilation system design, Part 3: Ultraviolet viral decontamination, and Part 4: Vaccine design and immune response. It is important to emphasize that the rapid speed at which the simulations operate makes the presented computational tools easily deployable as digital twins, i.e., digital replicas of complex systems that can be inexpensively and safely optimized in a virtual setting and then used in the physical world afterward, thus reducing the costs of experiments and also accelerating development of new technologies. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2022.

Evaluation of animal biosafety webinar series for professionals working in animal facilities across Pakistan during the COVID-19 pandemic

Experimental research with animals can help the prevention, cure, and alleviation of human ailments. Animal research facilities are critical for scientific advancement, but they can also pose a higher risk than other biomedical laboratories. Zoonosis, allergic reactions, bites, cuts, and scratches by animals are all substantial concerns that can occur in animal facilities. Furthermore, human error and unexpected animal behavior pose a risk not just to humans, but also to the environment and the animals themselves. The majority of biosafety and biosecurity training programs focus on clinical and biomedical laboratories dealing with human safety factors, with little emphasis on animal biosafety. The current virtual training was designed to improve biosafety and biosecurity capabilities of animal laboratory personnel, researchers, and veterinarians from different regions of Pakistan. The results revealed that understanding was improved regarding triggers for risk assessment in addition to annual and regular reviews (56% to 69%), biosecurity (21% to 50%), decontamination (17% to 35%), safe handling of sharps (21% to 35%), Dual Use Research of Concern (DURC) (17% to 40%), Personal Protective Equipment (PPE) usage by waste handlers (60.9% to 75%), waste management (56% to 85%), animal biosafety levels (40.57% to 45%), and good microbiological practices and procedures (17% to 35%). To bring human and animal laboratories up to the same level in terms of biosafety and biosecurity, it is critical to focus on areas that have been overlooked in the past. Training programs focusing on animal biosafety should be conducted more frequently to strengthen bio risk management systems in animal research facilities.Copyright © 2021

Stability of SARS-CoV-2 on the Army Combat Uniform and Recommendations for Cleaning.

SARS-CoV-2 is the virus responsible for the disease that is known as COVID-19. While there have been numerous studies detailing the survival rates of SARS-CoV-2 on various materials, there are currently no published data regarding whether this virus is stable on standard military uniforms. Consequently, there are no standard operating procedures for washing uniforms once exposed to the virus. This study aimed to determine whether SARS-CoV-2 could be removed from Army combat uniform material by washing with a commercially available detergent and tap water. Washing the fabric with detergent followed by a rinse step with tap water effectively removes detectable viral particles. Importantly, it was found that washing with hot water alone was not effective. Therefore, it is recommended that military personnel wash their uniforms with detergent and water as soon as possible after exposure to SARS-CoV-2; hot water should not be used as a substitute for detergent.

Review of the Effect of Continuous Use and Limited Reuse of N95 Respirators on Respirator Fit.

Background: Coronavirus disease 2019 (COVID-19) has led to severe shortages of filtering facepiece respirators (FFRs). As a result, extended use, limited reuse, and FFR decontamination have been utilized to extend the life of single-use FFRs. Although some studies have raised concerns that reuse could affect the FFR's ability to form a seal, no comprehensive literature review of the effect of extended use or limited reuse on FFR seal exists. Objective: The goal of this review was to assess the effect of extended use and reuse on respirator fit, with and without decontamination. Methods: Searches of PubMed and Medrxiv yielded 24 papers that included assessment of fit after extended use or limited reuse on a human. One additional handpicked paper was added. Results: Studies report a wide variation in the number of donnings and doffings before fit failure between different models of respirators. Additionally, while seal checks lack sufficient sensitivity to reliably detect fit failures, individuals who failed fit testing were often able to pass subsequent tests by re-positioning the respirator. Even with failure, respirators often maintained a substantially higher level of fit than a surgical mask, so they may still provide a level of protection in crisis settings. Conclusion: Based on currently available data, this literature review was unable to establish a consensus regarding the amount of time a respirator can be worn or the number of uses before fit failure will occur. Furthermore, variations in reuses before fit failure between different models of N95 respirators limit the ability to offer a comprehensive recommendation of greater than one reuse or a specific amount of wear time.

Study of ozone misting for sanitization of hospital facilities: A CFD approach

The COVID-19 pandemic has demonstrated the demand for more effective procedures for sanitizing environments, especially high-risk ones, such as hospitals. Several products are used as disinfectants, with ozone being one of the strongest oxidants known. High relative humidity helps reduce the contact time required for viruses and bacteria inactivation with ozone. Thus, this work aimed to analyze the dispersion of an ozonized mist by CFD simulation to sanitize a hospital operating room. To our best knowledge, for the first time, the dispersion of an ozonized mist was investigated by CFD. The mathematical and numerical models were validated with results from the literature. The decay kinetics of the ozonized mist was obtained experimentally, resulting in a first order reaction with a kinetic constant of 2.66 × 10−4 s−1. The numerical results of concentration on the surfaces were analyzed qualitatively and quantitatively, providing relevant information about the fluid dynamics of the sanitizing process. Ozone mist concentrations were higher on the walls close to the generator and lower on the furthest walls and the ceiling. The ozone mist concentration in the room reached an average of 11 mg/L. Five minutes of ozone mist generation and another five minutes of decay by air circulation were sufficient to provide an increase in ozone mist to concentrations above 4 mg/L, considered satisfactory for the sanitization of the operating room surfaces. [ FROM AUTHOR] Copyright of Ozone: Science & Engineering is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)

Ensuring effective infection prevention and control in the community.

Managing community-acquired infections remains an ongoing challenge for community nursing teams. The coronavirus disease 2019 (COVID-19) pandemic meant that community nurses had to ensure they were using evidence-based infection prevention and control measures to limit the effects of the pandemic and maintain patient safety. Community environments can be unpredictable, and compared with acute settings nurses will often lack the appropriate resources when visiting patients in their homes or in residential care. This article outlines effective infection prevention and control measures that nurses can implement in the community, such as the appropriate use of personal protective equipment, optimal hand hygiene, safe waste management and adherence to an aseptic technique.

Evaluation of the Microbiota and Integrity of Respirators Reused by Health Professionals in a Hospital Environment

The shortage of PFF2, N95, and KN95 respirators and their equivalents for the respiratory protection of the population and health professionals during COVID-19 pandemic has driven the adoption of alternative measures to address the lack of personal protective equipment (PPE). The use of surgical masks, handmade masks, and even the prolonged use of respirators were some of the measures adopted in response to the high demand for these products, and their consequent shortage. In this context, the present study evaluated the microbiota and integrity of reused PFF2 respirators in the central sterile services department of a hospital. Respirators that had been used for 0 h, 12 h, 24 h, and 36 h were sampled for the inoculation and cultivation of fungi and bacteria and the identification of their microbiota. To assess the integrity of the respirators, a filtration efficiency assessment test was conducted of the respirators used for 36 h. The results obtained showed that the microbiota of the respirators comprised commensal fungi and bacteria from the oral and nasal regions of human beings. It was also found that after 36 h of use, the respirators did not demonstrate a decrease in filtration efficiency;that is, they retained their 97% filtration efficiency. Considering the findings regarding the presence and pathogenicity of microorganisms, it is possible that the reuse of respirators for up to 36 h does not harm the health of immunocompetent users. In terms of PPE efficiency, no compromises were evidenced.

Assessing Mask Integrity and Fit of N95 Masks after 5 Cycles of Decontamination and Reuse in a Simulated Clinical Setting

Aim: To evaluate the effect of decontamination and reuse on N95 masks. Background(s): The coronavirus disease (COVID-19) pandemic has strained the global availability of masks. Such shortage represents a threat to healthcare workers (HCWs). Mask reprocessing and reuse may alleviate the shortage. Many laboratory studies have proven the effectiveness and feasibility of decontaminating N95 masks. However, very few had HCWs wearing them between cycles of decontamination. Our study evaluated mask integrity (assessed by qualitative mask fitting [QMF], as well as technical measures like bacterial filtration efficacy [BFE]) through five cycles of decontamination using four different modalities - steam, moist heat (MH), UV-C irradiation (UVCI), and hydrogen peroxide vaporization (HPV). Method(s): Each study cycle involved a HCW wearing a N95 mask for two hours, followed by the assigned decontamination process, and then a QMF. This was repeated for a maximum of 5 cycles, as long as the wearer passed QMF. 40 HCWs were recruited for each of the four decontamination modalities. The technical measures of mask integrity assessed were: BFE, Particulate Filtration Efficiency (PFE), Pressure Drop and Splash Resistance. Result(s): 60.6% (HPV) to 77.5% (MH) of the masks passed five cycles of wear and decontamination, as assessed by the wearers passing QMF all five times. MH-decontaminated masks retained all technical measures of integrity through all 5 cycles. HPV reduced masks' BFE after the fourth cycle while UVCI tended to increase the Pressure Drop. Conclusion(s): The results suggest that MH is a promising method for decontaminating N95 masks without compromising fit and integrity. [Figure presented] [Table presented]Copyright © 2023 Southern Society for Clinical Investigation.

COVID-19 pandemic: Practical advice for Endoscopy Units. Mistakes to be avoided. Experience of the Italian North-Eastern Venetian Region.

Italy is the second most affected by coronavirus epidemy country in the world. In this article, members of the Italian Society of Surgical Endoscopy analyze the work of endoscopic units during the COVID-19 pandemic. Authors explain how to stratify patients according to risk groups, how to put on and off personal protective equipment, list decontamination standards for endoscopic equipment and endoscopic room.Copyright © 2020, Media Sphera Publishing Group. All rights reserved.

Disinfecting Efficacy of an Ozonated Water Spray Chamber: Scientific Evidence of the Total and Partial Biocidal Effect on Personal Protective Equipment and in Vitro Analysis of a Viral Experimental Model

Due to the high recurrence of microbial infections, developing new technologies for preventing the dissemination of pathogens is essential, especially to prevent infection in humans. Thus, devices for the decontamination of surfaces reduce not only the spread of pathogens in the environment, but provide greater security and protection for communities. Ozone (O3) is a substance capable of reducing or eliminating several types of microorganisms owing to its biocidal capacity, including when it is dissolved in water. The objective of this study was to develop an instant decontamination device using ozonated water. To confirm its biocidal action and verify the device's efficacy, the reduction of the microbial load of important pathogens on personal protective equipment (PPE) was assessed. In addition, in order to confirm the biocidal action of ozonated water against SARS-CoV-2, in vitro tests on a viral model of Gammacoronavirus were performed. The results showed the efficacy of ozonated water in the disinfection device at concentration ranges of 0.3–0.6 mg/L and 0.7–0.9 mg/L of ozonated water, with growth reductions above 2 log10 for both concentration ranges tested and inactivation fractions above 60% (0.3–0.6 mg/L) and 80% (0.7–0.9 mg/L), with a high proportion of the tested PPE showing 100% microbial reduction. In vitro results for the evaluation of ozonated water in a viral model showed a 99.9% reduction percentage in the concentration range of 0.3 to 0.5 mg/L and a 99% reduction in the concentration range of 0.6 to 0.8 mg/L, with a 5.10 log EDI50/mL and 6.95 log EDI50/mL reduction, respectively. The instant decontamination system developed in this study proved effective for microbial reduction, and we confirmed the potential of ozonated water as a biocidal agent. Therefore, the proposed decontamination device could be considered as a tool for reducing contamination on surfaces using ozonated water.

Inactivation of the enveloped virus phi6 with hydrodynamic cavitation.

The COVID -19 pandemic reminded us that we need better contingency plans to prevent the spread of infectious agents and the occurrence of epidemics or pandemics. Although the transmissibility of SARS-CoV-2 in water has not been confirmed, there are studies that have reported on the presence of infectious coronaviruses in water and wastewater samples. Since standard water treatments are not designed to eliminate viruses, it is of utmost importance to explore advanced treatment processes that can improve water treatment and help inactivate viruses when needed. This is the first study to investigate the effects of hydrodynamic cavitation on the inactivation of bacteriophage phi6, an enveloped virus used as a SARS-CoV-2 surrogate in many studies. In two series of experiments with increasing and constant sample temperature, virus reduction of up to 6.3 logs was achieved. Inactivation of phi6 at temperatures of 10 and 20 °C occurs predominantly by the mechanical effect of cavitation and results in a reduction of up to 4.5 logs. At 30 °C, the reduction increases to up to 6 logs, where the temperature-induced increased susceptibility of the viral lipid envelope makes the virus more prone to inactivation. Furthermore, the control experiments without cavitation showed that the increased temperature alone is not sufficient to cause inactivation, but that additional mechanical stress is still required. The RNA degradation results confirmed that virus inactivation was due to the disrupted lipid bilayer and not to RNA damage. Hydrodynamic cavitation, therefore, has the potential to inactivate current and potentially emerging enveloped pathogenic viruses in water at lower, environmentally relevant temperatures.

Evaluation of environmental conditions as a decontamination approach for SARS-CoV-2 when applied to common library, archive and museum-related materials.

AIMS: The purpose of this study was to evaluate the effects of ambient or altered environmental conditions on the inactivation of SARS-CoV-2 applied to materials common in libraries, archives and museums. METHODS AND RESULTS: Porous and non-porous materials (e.g. paper, plastic protective book cover) were inoculated with approximately 1 × 105 TCID50 SARS CoV-2 (USA-WA1/2020), dried, placed within test chamber in either a stacked or unstacked configuration, and exposed to environmental conditions ranging from 4 to 29°C at 40 ± 10% relative humidity. The amount of infectious SARS-CoV-2 was then assessed at various timepoints from 0 to 10 days. Ambient conditions resulted in varying inactivation rates per material type. Virus inactivation rate decreased when materials were stacked or at colder temperatures. Virus inactivation rate increased when materials were unstacked or at warmer temperatures. CONCLUSIONS: SARS-CoV-2 at ambient conditions resulted in the inactivation of virus below limit of quantitation (LOQ) for all materials by Day 8. Warmer temperatures, for a subset of materials, increased SARS-CoV-2 inactivation, and all were

Exhaled gases and the potential of cross infection from NIV machines

Background: The indications for Long Term Ventilation (LTV) are expanding. Pneumonia is common in these patients and transmission of bacterial infections, and more recently COVID-19 infection, between users of ventilators is a concern. UK national standards recommend bacterial/viral filters for use with acute Non-Invasive Ventilation (NIV) to protect the ventilator from contamination. However, there are no recommendations made for LTV. UK National guidance also explicitly states that there is no airflow from the patient to the ventilator.1 Aims and objectives: To investigate whether exhaled gas reaches the ventilator outlet. Method(s): We conducted experiments on three ventilators with different circuits during NIV delivered to a member of the study team using standard clinical settings. We used a side-stream end tidal CO2 (EtCO2) analyser attached to the tubing adjacent to the ventilator outlet as shown in the figure. Result(s): Regardless of ventilator and circuit used we demonstrated that exhaled gas reaches the ventilator outlet during NIV. EtCO2 values were 1.6-3.7kPa. Conclusion(s): Exhaled gas reaches the ventilator outlet during NIV. This raises an urgent requirement within the LTV community to test ventilators for bacterial and viral colonisation, consider the use of bacterial/viral filters, and discuss routine decontamination of these devices between individual patient uses. (Figure Presented).

New generation washable PES membrane face mask for virus filtration

Membrane materials might be used for face protection because they can decontaminate the inhaled air from particle pollution and viruses like the SARS-Cov0-2 which damages our respiration system. In this study, plyethersulfone membranes (PES) were synthesized with green solvent at room temperature and its filtration effectiveness was investigated against nano-bacteria (size 0.05 to 0.2 µm) by measuring their Bacterial Filtration Efficiency (BFE) and micro aerosol size (0.3 µm), and Particulate Filtration Efficiency (PFE). The average SARS-CoV-2 diameters are between 50 nm to 160 nm. A series of experiments were performed to accomplish between 0.03 to 0.21 µm PES sponge like diameters so that can be used for SARS-CoV-2 filtration. Results showed that nanofiltration/ultrafiltration could filter 99.9% of bacteria and aerosol from contaminated air the size of the Covid-19 molecule.

Safe Use of Sodium Dodecyl Sulfate (SDS) to Deactivate SARS-CoV-2: An Evidence-Based Systematic Review

Background: Coronavirus disease (COVID-19) has now morphed into the most serious healthcare challenge that the world has faced in a century. The coronavirus disease (COVID-19) was declared as a public health emergency of international concern (PHEIC) on January 30, 2020, and a pandemic on March 11 by the World Health Organization (WHO). The number of cases and the death toll are rapidly increasing frequently because of its fast transmission from human to human through droplets, contaminated hands or body, and inanimate surfaces. Objective(s): SDS has been found to exhibit broad-spectrum and effective microbicidal and viral inactivation agents through the denaturation of both envelope and non-envelop proteins Methods: Viable SARS-COV-2 particles may also be found on contaminated sites such as steel surfaces, plastic surfaces, stainless steel, cardboard, and glass surfaces that can serve as a source of virus transmission. We reviewed the available literature about the SARS-CoV-2 persistence on inanimate surfaces as well as the decontamination strategies of corona and other viruses by using Sodium dodecyl sulfate (SDS) as well as other cleaning chemicals and disinfectants. Result(s): The efficacy of SDS has been amply demonstrated in several studies involving human immunodeficiency virus (HIV), human papillomavirus (HPV) and herpes simplex virus (HSV). SDS has also been found as deactivator of SARS-CoV-2. In toxic profile, up to 1% concentration of SDS is safe for humans and showed no toxic effect if ingested. Conclusion(s): Since no specific treatment is available as yet so containment and prevention continue to be important strategies against COVID-19. In this context, SDS can be an effective chemical disinfectant to slow and stop the further transmissions and spread of COVID-19.Copyright © 2021 Bentham Science Publishers.

Sanitization Using Autonomous Drone

Since the COVID -19 epidemic has nearly brought about global catastrophe, every chance to make things better must be considered. One such technique for improvement is airborne decontamination. Researching this method's efficacy in the pandemic is vital since it can be used for surface cleaning of bigger areas. There are numerous instances of using drones to disinfect areas affected by epidemics, but best practices and factors affecting effectiveness have not yet been found. The adaptable uses of agricultural drones are evident from reports about utilizing drones for disinfection during a pandemic. The authors of this study calculated the potential amount of disinfectant fluid per unit area using various parameters for fly speed, flight altitude, and flow rate. As a result, by adjusting the settings, a range of disinfectant concentrations per unit area can be provided. Even though the results create a lot of new queries, they can be used to determine appropriate flying characteristics based on various disinfection liquids. © 2022 IEEE.

Automation of Large-Scale Gaseous Ozonation: A Case Study of Textile and PPE Decontamination

There is an ever-growing need in several industries to disinfect or sanitise products (i.e., to reduce or eliminate pathogenic microorganisms from their surfaces). Gaseous ozone has been widely applied for this purpose, particularly during the era of the COVID-19 pandemic. However, the large-scale deployment of this technology usually involves a manually-operated chamber, into which articles are loaded and subsequently unloaded after treatment—a batch process. Although the development of large-scale, automated and continuous ozonation equipment has hardly been reported in the literature, this has tremendous potential for industries seeking to decontaminate certain articles/products in a rapid and effective manner. In this paper, an overview of the design and implementation considerations for such an undertaking is evaluated. By presenting a case study for a developed automated system for clothing and personal protective equipment (PPE) disinfection, we provide key data regarding the automation procedure/design's considerations, risks, material compatibility, safety, sustainability and process economics. Our analysis shows that the transfer time for garments between successive chambers and the agility of the sliding doors are crucial to achieving the desired throughput. The automated system is capable of effectively treating (20 ppm ozone for 4 min) 20,000 garments within an 8-h shift, based on a transfer time of 2 min and a sliding door speed of 0.4 m/s. The flexibility of the system allows for variation in the concentration or exposure time, depending on the contamination level and the consequent decontamination efficiency desired. This flexibility significantly limits the degradation of the material during treatment. A return on investment of 47% is estimated for this novel system. © 2023 by the authors.

An Automated Patient Bed Cleaner Using UV Rays

Coronavirus (COVID-19) is an infectious illness due to serious respiratory trouble. It is impacted numerous humans and has asserted the living expectancy of a greater number of persons from all over the planet. The maturation period of this virus, on typically about 5-6 days but it might also be up to 2 weeks. Throughout this period, the individual may not feel any indications but could still be transmissible. A person could develop this disease if he/ she inhales the virus while a diseased person/ virus carrier within close vicinity sneezes or coughs otherwise tapping an infected place in addition to afterward again his/ her eyes, nose or mouth. To prevent this, the region of the COVID-19 patient must be decontaminated with virucidal disinfectants, such as and 0.05% sodium hypochlorite (NaClO) and ethanol-based products (at least 70%) an optional technique used is UV light sterilization. Ultraviolet (UV) sterilization technology is used to help reduce micro-organisms that can remain on surfaces after basic sprinkling to the minimum amount. The proposed work has established an UV robot or UV bot to perform decontamination in an operating room or in-patients room. Three 19.3-watt UV lights are positioned in a 360-degree circle on the UV bot platform. It used an integrated system based on a microprocessor and a metal frame to aid in navigation in a fixed path to avoid barriers. In addition, a sanitizer dispenser is also included to clean the viral organisms, which is spread through the water droplets of the patient. © 2022 IEEE.

Structure, Morphology, and Surface Chemistry of Surgical Masks and Their Evolution up to 10 Washing Cycles

The Covid-19 crisis has led to a massive surge in the use of surgical masks worldwide, causing risks of shortages and high pollution. Various decontamination techniques are currently being studied to reduce these risks by allowing the reuse of masks. In this study, surgical masks were washed up to 10 times, each cycle under the same conditions. The consequences of the washing cycles on the structure, fiber morphology, and surface chemistry have been studied through several characterization techniques: scanning electron microscopy, wetting angle measurements, infrared spectroscopy, X-ray diffraction, and X-ray photoelectrons spectroscopy. The washing process did not induce large changes in the hydrophobicity of the surface, the contact angle remaining constant throughout the cycles. The composition observed in the IR spectrum also remained unchanged for washed masks up to 10 cycles. Some slight variations were observed during X-ray analysis: the crystallinity of the fibers as well as the size of the crystals increases with the number of wash cycles. The XPS analysis shows that after 10 cycles, the surface of the masks underwent a slight oxidation. In the SEM images, changes were observed in the arrangement of the fibers, which are more visible the more times the mask has been washed: they align themselves in bundles, form areas with holes in the mask layer, and are crushed in some areas. © 2023 American Chemical Society