Isolation Ward Research Articles

Pathogenicity potential of enterococci isolated from a Veterinary Biological Isolation and Containment Unit.

Enterococcus are considered an important genus in terms of Hospital-Acquired Infections (HAIs), which means that their characterization regarding resistance and virulence profiles in the hospital environment is of extreme importance. This article addresses this issue through the characterization of enterococci collected from a Veterinary Biological Isolation and Containment Unit (BICU). A total of 73 isolates, collected from different surfaces of a Veterinary BICU, were identified as Enterococcus through PCR at species level, after which 34 isolates were selected as representatives using (GTG)5 fingerprinting. These isolates were further characterized phenotypically in terms of antimicrobial resistance through disk diffusion and of virulence factors' expression. The majority of the enterococci isolated presented resistance to erythromycin (79.4%), ampicillin (73.5%), amoxicillin-clavulanic acid (70.6%), tetracycline (67.6%), ciprofloxacin (58.8%) and levofloxacin (50.0%), and were able to produce hemolysin (88.2%) and biofilm (82.3%). Furthermore, in terms of pathogenicity, three isolates (8.8%) were classified as high threats and two (5.9%) as moderate threats. The degree of resistance, production of virulence factors and the percentage of isolates classified as moderate or high threat means that a constant vigilance of such strains in veterinary units, but also in clinics and hospitals in general, is an important tool in terms of infection prevention and consequent reduction of HAIs.

Test and sensitivity analysis of base‐isolated steel frame with low‐friction spherical sliding bearings

AbstractIn Japan, spherical sliding bearings with low friction coefficients are gaining popularity for base‐isolating low‐rise frames that are relatively lightweight. However, the complete dataset of isolators and a base‐isolated frame for evaluating the model sensitivity and response uncertainty are limited. This study first presents the design process, isolation unit‐ and frame‐level testing, and a blind prediction contest conducted on the occasion of full‐scale shaking table testing of a three‐story base‐isolated hospital specimen. The design process utilizes a numerical model that accounts for the velocity and contact pressure dependencies and requires soft‐ and hard‐case simulations with nominal friction coefficients plus and minus standard deviation to consider the uncertainties associated with the bearing behavior. The pre‐shipment isolation unit and frame shake table testing yielded an invaluable dataset for bearings under normal and low contact pressures, low and high velocities, and constant and varying axial loads. The accompanying blind prediction contest provided a valuable dataset for rethinking the impact of modeling uncertainty. In‐depth data analysis and sensitivity analysis were conducted. The sliding coefficient increased under low‐contact pressure and low‐velocity conditions. The static friction coefficient was 1.9 to 4.5 times higher than the dynamic coefficient, but this had little impact on the residual displacement, cumulative travel, and maximum story shear force. The axial force fluctuation, vertical motion, and two‐directional input did not significantly affect the bearing behavior in the test. The test and the following simulations confirmed that the low friction coefficient helped the building contents, that is, medical equipment in this study, remain in order under near‐fault and long‐period ground motions.

Electroencephalography in emerging viral infections: Lessons learned from implementing an EEG unit in a Lassa fever isolation ward in Nigeria.

Electroencephalography (EEG) has been used for almost a century in well-equipped medical centers to facilitate the diagnosis of epilepsy and other brain disorders. Lassa fever (LF) and other emerging viral infections (EVI) are known to cause neurological complications, including meningitis, seizures, and encephalopathy, though to date it remains unclear whether these are secondary to metabolic disturbances caused by the disease or by direct involvement of the central nervous system (CNS). To better characterize how Lassa virus (LASV) affects the CNS, we established an EEG diagnostic unit in the LF isolation ward at Irrua Specialist Teaching Hospital in Edo State, Nigeria. Here, we report on the specific difficulties to successful implementation of EEG in this highly challenging setting. Technical artefacts due to electrical interferences and interrupted power supply, artefacts deriving from a partly improvised EEG setup within a high consequence pathogen isolation ward, and environmental factors, such as heat in the endemic West African setting are among the main difficulties encountered when setting up this diagnostic facility. It takes experienced neurophysiologists to distinguish such artefacts from actual EEG abnormalities as many of them are not commonly encountered to this extent in well-equipped EEG laboratories and can easily be confused with pathologies. The EEG recording process is further complicated by biosafety considerations and the necessity of wearing extensive personal protective equipment. Nevertheless, with the help of experienced neurophysiologists, it is possible to correctly set up the facility and interpret recordings. Taking the above into consideration, EEG is valuable in identifying CNS involvement in emerging infections, particularly regarding assessment of encephalitis, differential diagnosis of impaired consciousness and treatment adjustment in patients with symptomatic seizures. Although highly challenging under these circumstances, EEG can be an important, noninvasive diagnostic tool for neurological complications in EVI where other more advanced imaging modalities are not available.

D-dimer as a Predictor of ICU Admission and Mortality in COVID-19 Patients: Insights From a Two-Year Retrospective Study From a Tertiary Care Center in South India.

Introduction Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced pneumonitis results in a prothrombotic and hypercoagulable state. Prognostic indicators are crucial for identifying patients at risk of complications. D-dimer, a degradation product of cross-linked fibrin, is a specific marker for thrombosis. Elevated D-dimer levels have been strongly correlated with poor prognosis and increased severity of illness in COVID-19 patients. Given D-dimer's eight-hour half-life, periodic measurement is necessary to track disease progression. This study aimed to analyze and derive threshold and peak D-dimer values to predict outcomes in COVID-19 patients, comparing those treated in isolation wards to those requiring intensive care. Methods This two-year retrospective observational study included patients above 18 years with confirmed COVID-19. Patients were categorized into those treated in isolation wards and those admitted to the intensive care unit (ICU). Based on the outcome, they were further divided into survivors and non-survivors. Demographic and outcome-related data were collected from the hospital's laboratory information system. Serial D-dimer measurements were taken at eight time points. Statistical analysis was performed using the Mann-Whitney test for laboratory values and the chi-square test for demographic data. Receiver operating characteristic (ROC) curve analysis was utilized to derive critical D-dimer values. The area under the curve (AUC) was calculated for initial and peak D-dimer values. Results Of 2.149 patients with confirmed COVID-19, 811 (38%) presented with elevated D-dimer levels. ICU admission was required for 239 patients, either due to direct admission or worsening conditions. An initial D-dimer value of ≥0.93 mg/L FEU indicated the need for ICU admission, while a peak D-dimer value of 5.65 mg/L FEU predicted mortality. The AUC for the initial D-dimer was 0.60 (95% CI: 0.55-0.64), indicating moderate discriminatory power. The AUC for the peak D-dimer was 0.58 (95% CI: 0.54-0.62), suggesting lower predictive accuracy for peak values. Sensitivity was high for both initial (0.925) and peak (0.960) D-dimer values, although specificity was lower, especially for the peak D-dimer (0.486), resulting in a higher rate of false positives. Among the ICU patients, the age range was 27-97 years, with a mean of 53.5 years. Males were more affected than females (71% vs. 29%), with a male-to-female ratio of 1.4:1. Of the ICU patients, 64.8% recovered, while 35.2% succumbed to the disease. Younger patients (mean age: 50.5 ± 12 years) recovered faster than older patients (mean age: 64 ± 16 years), with a significant difference in recovery time (p < 0.001). Gender did not significantly impact outcomes (p = 0.743). Survivors spent less time in the ICU (3-7 days) compared to non-survivors (4-14 days) (p = 0.041). Conclusion Serial D-dimer monitoring is essential for predicting outcomes and guiding treatment in COVID-19 patients. Initial and peak D-dimer values can help identify patients requiring intensive care and those at risk of mortality, allowing for timely interventions. D-dimer levels should be integrated into routine clinical assessments for managing COVID-19 patients.

Development of optimal indoor air disinfection and ventilation protocols for airborne infectious diseases.

Since the COVID-19 pandemic, there has been persistent emphasis on the importance of indoor air disinfection and ventilation in isolation units in the hospital environment. Nevertheless, no optimal and concrete disinfection protocol has been proposed to inactivate the viruses as quickly as possible. In this study, we experimentally evaluated various ventilation and disinfection protocols based on the combination of negative-pressure ventilation, ultraviolet (UV) light illumination, and Hypochlorous acid (HOCl) spray against three active virus species in a 3.5 cubic meters isolation unit. This small-size unit has gained attention during the pandemic due to the high demand for compact mobile laboratory systems capable of rapid disease diagnosis. In accordance with the WHO laboratory biosafety guidance, which states that all enclosed units where diagnostic work is conducted must ensure proper ventilation and disinfection activities, we aim to propose virus removal protocols for units compact enough to be installed within a van or deployed outdoor. The results confirmed the superiority (in terms of virus removal rate and time required) of the virus removal methods in the order of UV light, ventilation, and HOCl spray. Ultimately, we propose two optimal protocols: (i) UV light alone for three minutes, and (ii) UV light with ventilation for three minutes, followed by one-minute ventilation only. The time span of three minutes in the latter protocol is based on the clinical practice such that the medical staffs have a sufficient time to process the samples taken in transition to next patient to care.

Combined performance of upper-room UVGI and ceiling-mounted air cleaners for removing active bioaerosol

Upper-room ultraviolet germicidal irradiation (UR-UVGI) and ceiling-mounted air cleaner (CM-AC) technologies contribute to curbing the spread of infectious diseases such as COVID-19. However, there is a lack of detailed studies on the performance differences between these two control technologies for reducing viral concentrations and infection risk in isolation ward environments with different ventilation modes, especially when used alone versus in combination. Therefore, this study performed numerical simulations under three ventilation modes, namely, downward ventilation (DWV), stratum ventilation (SV), and displacement ventilation (DV), by the Eulerian-Lagrangian method combined with the UV inactivation model. The viral disinfection performance of UR-UVGI and CM-AC was parametrically analyzed. The effectiveness of the combined application of these two control technologies in wards was evaluated. The results showed that expanding the irradiation range was more effective in enhancing the UR-UVGI performance with the same total UV flux. When using UR-UVGI only, DWV disinfected better at the same irradiation flux. In CM-AC cases, the viral aerosol removal efficiency was the greatest in DV. UR-UVGI and CM-AC had advantages in active bioaerosol removal in overall and localized indoor spaces, respectively. The combined application was recommended to maximize the air cleanliness. Under the role of UR-UVGI, a high level of disinfection could be achieved using CM-AC with low ventilation rates. When the CM-AC ventilation rate was 150 m3/h and the UV irradiance was 30 μW/cm2, the viral disinfection of DV exceeded 90%, while that of DWV was also close to 90%. The findings could provide insights to further lower the transmission risk of infectious diseases.

Infection prevention and control status at public hospitals and factors associated with COVID-19 infection among healthcare workers in Myanmar: A cross-sectional study

BackgroundHospitals should prepare for emerging diseases and protect healthcare workers (HCWs) from work-related infection. This study aims to assess public hospital preparedness for the coronavirus disease 2019 (COVID-19) a year after the Myanmar government began implementing COVID-19 prevention measures, and to identify factors associated with work-related COVID-19 infection among HCWs in Myanmar.MethodsIn January 2021, data were collected from 101 hospitals and 706 HCWs who had COVID-19 in Myanmar in 2020. Data from the hospitals included basic information, the status of infection prevention and control (IPC), the preparedness for COVID-19 (guidelines, checklists, fever screening, patient pathway, and training), handwashing facilities, and availability of personal protective equipment (PPE). Data of COVID-19 infected HCWs included age, occupation, workplace, severity and source of COVID-19 infection, knowledge and practice of handwashing, and working environment. Chi-square test was performed to compare the preparedness for COVID-19 among three hospital levels (primary, secondary and tertiary levels). Logistic regression analysis was performed to identify the associated factors of work-related infection of HCWs.ResultsThe total number of beds, HCWs, and COVID-19 patients in 2020 at the 101 hospitals was 12,888, 14,421, and 19,835, respectively. The availability of PPE was high in hospitals at all levels. Approximately 80% of hospitals had functional status of IPC, set up fever screening and patient pathway, and provided training on IPC and COVID-19. However, only 39.6% of hospitals had developed COVID-19 guidelines and 55.4% had developed checklists. The percentage of hospitals that prepared each measurement was lowest at the primary level. The factors associated with work-related COVID-19 among HCWs were being 30–39 years old, working as a doctor, working at isolation wards, having disinfection technique training, and having enough PPE at the workplace.ConclusionThe preparedness for COVID-19 at public hospitals in Myanmar in January 2021 was insufficient, especially in the availability of the guidelines and checklists and at primary hospitals. A support system for hospital pandemic preparedness and monitoring of IPC implementation is needed. The government should prepare for emerging diseases and provide appropriate and adequate PPE and additional training to all HCWs, especially HCWs who work for isolation wards.

Evaluation of the effectiveness of a segmented alternating shift pattern based on wearable vital signs monitoring devices during COVID-19: a cross-sectional study

AimTo explore the feasibility and effectiveness of an alternating shift pattern in two-hour segments in the state of emergency management of public health events.MethodsA cross-sectional research design was conducted in our study. The nursing staff working in the admission ward of suspected or confirmed patients with COVID-19 in December 2022 were selected as subjects by the whole-group sampling method. We adopted a shift pattern of alternating shifts every two-hour in the isolation wards. The vital signs parameters were captured by uniformly wearing the multi-signs sensing devices, and the questionnaires collected the symptoms.ResultsSixty-seven female participants, with a mean age of 33.09 ± 5.96 years, were included in this study. Measurements of body temperature (T), blood oxygen saturation (SpO2), respiratory rate (RR), and heart rate (HR) while wearing personal protective equipment (PPE) all remained within normal limits. None of the nurses reported sweating, dizziness, blurred vision, palpitations, or dyspnea. Statistical analysis showed significant differences between the critical care group and the non-critical care group in terms of age (P = 0.041), working duration (P = 0.036), and the total number of entries into isolation areas for nursing care (rounds) (P = 0.007). However, there were no statistically significant differences in vital signs based on age, work duration, or body mass index (BMI). The data indicated a notable increase in body temperature compared to other vital sign parameters with increasing work time while wearing PPE. Body temperature approached the upper limit when working close to 2 h long.ConclusionsThe alternating shift pattern in two-hour segments can effectively maintain the physical well-being of nurses wearing PPE without increasing the burden on nursing staff or the wastage of protective materials. This approach is recommended for addressing similar public health events in the future.

Improving Safety and Comfort of Healthcare Workers Caring for Patients With High-Consequence Infectious Diseases in a High-Level Isolation Unit Using Innovative Approaches.

Patients with high-consequence infectious diseases (HCIDs) require high-quality care by specially trained staff in a high-level isolation unit (HLIU) that follows strict infection prevention and control (IPC) measures. Caring for patients with (suspected) HCID is challenging, mainly because of the strict personal protective equipment (PPE) and IPC protocols healthcare workers (HCW) must adhere to for protection. The Radboud University Medical Center, located in Nijmegen, the Netherlands, has been a dedicated HLIU facility since 2008. A newly built HLIU opened in May 2022, and encouraged us to review the existing PPE selection, IPC protocols, and HCID training program to improve safety and comfort for HCWs working in the HLIU. Based on a systematic search through (inter)national HCID PPE guidelines and semistructured interviews with end users, we selected an improved, more comfortable set of PPE. Additionally, we developed a more concise and easier-to-use patient care process flow and implemented a new teaching strategy. The new way of working was tested in October 2022 when the first 2 patients with suspected HCID were admitted to our unit. We used surveys to evaluate the experiences of HCWs involved in this care to further improve the workflow of the unit. When optimizing safety and comfort for HCWs, it is important to consider (inter)national guidelines as well as user preferences. By systematically evaluating recent experiences of patient admission to the HLIU and then adjusting protocols and training, we can ensure that the quality of provided healthcare and the safety of HCWs working in the HLIU remains high.

Building a High-Level Isolation Unit in Rwanda and Establishing a Training Program for the Medical Management of Patients With High-Consequence Infectious Diseases.

Rwanda is a country in East Africa, a region characterized by highly mobile populations and outbreaks of high-consequence infectious diseases occurring on a regular basis. To increase the level of outbreak preparedness in the region, the Rwandan government and the German Ministry of Health signed a joint agreement to construct a new high-level isolation unit in Rwanda, the first in East Africa, and implement a training program for Rwandan healthcare workers to equip them with the necessary skills and knowledge for medical management of patients under high-level isolation conditions, including intensive care treatment. To better understand the scope and format of the planned training program, a needs assessment was performed based on findings from a standardized survey of 4 intensive care units in Rwanda as well as observations from 2 members of a German high-level isolation unit who completed clinical internships at Rwandan hospitals. In this case study, we describe the necessary steps to promote the sustainability and capabilities of the new high-level isolation unit in Kigali and ensure the successful implementation of the training program.

The Role of High-Level Isolation Units in Response to High-Consequence and Emerging Infectious Diseases: Experience of the German STAKOB Network.

This case study describes the experience of the German Permanent Working Group of Competence and Treatment Centers for High Consequence Infectious Diseases, known as STAKOB (Ständiger Arbeitskreis der Kompetenz- und Behandlungszentren für Krankheiten durch hochpathogene Erreger). STAKOB brings together public health authorities (competence centers) and high-level isolation units (treatment centers) to collaborate on the clinical management of high-consequence infectious diseases (HCIDs) and emerging infectious diseases. The network is coordinated by the Robert Koch Institute, Germany's federal public health institute. The main tasks of STAKOB are to strengthen HCID clinical and public health management and increase expert knowledge on HCID and non-HCID emerging infectious diseases in Germany. STAKOB enables the exchange of knowledge and experiences; development of guidelines on infection prevention and control measures, clinical management, and therapy; and support for the World Health Organization and other outbreak responses internationally. The past years have shown how important the STAKOB network is for Germany-not only in providing critical care for HCID cases but also increasing capacity to support public health and clinical management of emerging infectious disease cases. However, maintaining several high-level isolation units in Germany requires a high commitment of financial, material, and human resources. Due to the rarity of HCID and emerging infectious disease events, maintaining the appropriate level of preparedness and ensuring sufficient investments is an ongoing struggle. Nevertheless, it is essential to have a network ready to react to HCID and non-HCID emerging infectious diseases in times of a changing biosecurity and infectious landscape.

Implementation of a High-Level Isolation Unit Readiness Checklist in the Irish Setting.

A high-level isolation unit (HLIU) is a specially designed biocontainment unit for suspected or confirmed high-consequence infectious diseases. For most HLIUs, maintaining readiness during times of inactivity is a challenge. In this case study, we describe a checklist approach to assess HLIU readiness to rapidly operate upon activation. This checklist includes readiness criteria in several domains, such as infrastructure, human resources, and material supplies, that are required to safely activate the unit at any time. The checklist audit tool was derived from a novel activation readiness checklist published by the biocontainment unit at The Johns Hopkins Hospital in Baltimore, Maryland. It was then adapted for the Irish healthcare setting and implemented at the Mater Misericordiae University Hospital, Ireland's current isolation facility. Results from the audit were also used to inform recommendations for the construction of a new HLIU to open in 2025. The audit tool is user friendly, practical, and focuses on the essential elements of readiness to ensure a successful rapid operation.

Clinical Management of Hospitalized Patients With High-Consequence Infectious Diseases in England.

Infectious disease physicians in England have been diagnosing and managing occasional cases of viral hemorrhagic fever since 1971, including the United Kingdom's first case of Ebola virus disease in 1976. Specialist isolation facilities to provide safe and effective care have been present since that time. Following the emergence of Middle East respiratory syndrome (MERS) in 2012, and the avian influenza A (H7N9) outbreak in 2013, and the 2014-2016 Ebola virus disease outbreak in West Africa, clinical and public health preparedness and response pathways in England have been strengthened for these types of diseases, now called high-consequence infectious diseases (HCIDs). The HCID program, led by NHS England and Public Health England between 2016 and 2018, helped to deliver these enhancements, which have since been used on multiple occasions for new UK cases and outbreaks of MERS, mpox, avian influenza, and Lassa fever. Additionally, HCID pathways were activated for COVID-19 during the first 3 months of 2020, before the pandemic had been declared and little was known about COVID-19 but HCID status had been assigned temporarily to COVID-19 as a precaution. The HCID program also led to the commissioning of a network of new airborne HCID treatment centers in England, to supplement the existing network of contact HCID treatment centers, which includes the United Kingdom's only 2 high-level isolation units. In this case study, the authors describe the airborne and contact HCID treatment center networks in England, including their formation and structures, their approach to safe and effective clinical management of patients with HCIDs in the United Kingdom, and challenges they may face going forward.

ADP-based online compensation hierarchical sliding-mode control for partially unknown switched nonlinear systems with actuator failures

This article investigates an adaptive dynamic programming-based online compensation hierarchical sliding-mode control problem for a class of partially unknown switched nonlinear systems with actuator failures and uncertain perturbations under an identifier-critic neural networks architecture. Firstly, by introducing a cost function related to hierarchical sliding-mode surfaces for the nominal system, the original control problem is equivalently converted into an optimal control problem. To obtain this optimal control policy, the Hamilton–Jacobi–Bellman equation is solved through an adaptive dynamic programming method. Compared with conventional adaptive dynamic programming methods, the identifier-critic network architecture not only overcomes the limitation on the unknown internal dynamic but also eliminates the approximation error arising from the actor network. The weights in the critic network are tuned via the gradient descent approach and the experience replay technology, such that the persistence of excitation condition can be relaxed. Then, a compensation term containing hierarchical sliding-mode surfaces is used to offset uncertain actuator failures without the fault detection and isolation unit. Based on the Lyapunov stability theory, all states of the closed-loop nonlinear system are stable in the sense of uniformly ultimately boundedness. Finally, numerical and practical examples are given to demonstrate the effectiveness of our presented online compensation control strategy.

Transport of Patients With High-Consequence Infectious Diseases: Development of European Capacity in Norway.

Infection of Western aid workers with Ebola virus disease during the 2014-2016 West African outbreak demonstrated the need for medical evacuation to high-level isolation units in Europe and the United States. In Norway, an ad hoc preparedness team was established for aeromedical evacuation in case of need. In October 2014, this team transported an infected aid worker from the military section of Oslo Airport to Oslo University Hospital. To maintain and strengthen the capacity for domestic ambulance transport on the ground and in the air, the Norwegian Medical Emergency Response Team for High Consequence Infectious Diseases (in Norway known as "Nasjonalt medisinsk utrykningsteam for høyrisikosmitte"), or NORTH, was established as a permanent service in 2017. Recognizing the expertise of this domestic team, Norway was subsequently entrusted with the task of enhancing the European aeromedical transport capacity for high-consequence infectious diseases and establishing the Norwegian rescEU Jet Air Ambulance for Transport of Highly Infectious Patients, or NOJAHIP, in 2022. In this case study, we present experiences and lessons learned from these 2 services and discuss how they can be further developed.

A Virtual Assessment Model for At-Home Evaluation of Suspected Viral Hemorrhagic Fever Cases.

The Sudan virus disease outbreak in 2022 prompted the Denver Health High-Risk Infection Team (HITeam) to evaluate and implement novel strategies to respond to viral hemorrhagic fever (VHF) events. To improve the VHF response, HITeam members developed a virtual assessment model (VAM) for at-home evaluation of individuals who are suspected of having a VHF. The VAM incorporates aspects of care that would normally be rendered in a high-level isolation unit-including assessment and monitoring, specimen collection, provider consultation, patient and family teaching, and pharmaceutical intervention-into a mobile framework in which team members respond to a suspected case at the individual's home. Building this capability allows for more thorough assessment of a suspect case in the field, as well as the postponement of a decision about activation of the high-level isolation unit until more information is available. Development, testing, and implementation of the VAM required input from an interdisciplinary group of partners that demonstrated the ability of nurses, physicians, laboratorians, paramedics, emergency medical technicians, and public health personnel to integrate into 1 cohesive care team. The resulting model recenters VHF care on the patient by allowing the care team to gather critical information in an environment that is more comfortable for the suspect case while keeping communities safe and lowering exposure risks. The VAM has long-term sustainability implications for global VHF programs and provides solutions for broader challenges in healthcare by modeling cost-effective, patient-centered care within the highly nuanced subspecialty of special pathogen care.

Use of wearable ventilation for reducing the infection risk of healthcare workers in isolation wards: A numerical study

This study investigates the protective effectiveness of a novel head-mounted air supply (HAS) system on healthcare workers (HCWs) in COVID-19 isolation wards. The study employs computational fluid dynamics (CFD) to explore the effectiveness of the HAS and the infection probability for HCWs during constant exhaling and coughing of patients. It also studies the effect of air changes per hour (ACH) and exhaust outlet locations in the isolation ward on the infection probability of the HCW. Additionally, the effectiveness between the HAS and various types of common masks is compared. Results indicate that when the flow rate of the HAS reaches 10 L/s with supplying clean air, the infection probability of the HCW can be reduced from approximately 30 % without protection to below 0.18 %. Patients' coughing increases the infection probability of the HCW by approximately tenfold within a short period, and wearing the HAS can effectively reduce the effect of patients’ coughing on the HCW. When ACH increases, the infection probability of the HCW decreases. Wearing the HAS can mitigate the effects of changes in ACH, with an infection probability below 0.18 % at 9 ACH or above. Ceiling-level exhausts are more effective than floor-level exhausts in removing pollutants from the ward. Under experimental settings, HAS with suitable parameters may be more effective than commonly used masks in terms of reducing the infection probability of the wearer. These findings provide valuable references for the application of wearable ventilations in hospital environments.

Role of ACE2 and TMPRSS2 polymorphisms in clinical severity and outcomes of COVID-19 in Egypt.

The clinical presentations of coronavirus disease 2019 (COVID-19) exhibit significant variation, ranging from asymptomatic cases to mortality resulting from severe pneumonia. Host genetics can partially explain this variation. This study evaluated possible associations between severity and outcome of COVID-19 and single nucleotide polymorphism (SNP) rs2285666 in the ACE2 gene and SNP rs2070788 in the TMPRSS2 gene. The study included a sample of 100 consecutive adult patients admitted to the COVID-19 Isolation and Intensive Care Units of the Zagazig University Hospitals, Zagazig, Egypt from July 2021 to November 2021. For rs2285666, polymerase chain reaction-restriction fragment length polymorphism was carried out. For rs2070788, real-time polymerase chain reaction was performed. For rs2285666, the GA genotype was the most frequent among female patients (39% [16/41]) and the A genotype was more prevalent among male patients (54.2% [32/59]). For rs2070788, the AA genotype was the most frequent among all patients (46% [46/100]). No rs2285666 or rs2070788 genotypes or allele frequencies had significant associations with either severity or outcomes of patients. This study found no significant associations of COVID-19 severity or outcomes of patients with genotypes or allele frequencies of the rs2285666 SNP in the ACE2 gene or the rs2070788 SNP of the TMPRSS2 gene. The search for other genetic associations with COVID-19 infection is still required. The study reveals that host genetics explain the variation observed in the disease. Specific genetic variants can confer either increased susceptibility or resistance to the disease.

Airflow and aerosol transport in the hospital isolation zone based on dynamic scenarios

To contain the leakage of viral aerosols, buffer rooms are usually provided in front of isolation wards. However, dynamic events of door movement and healthcare worker (HCW) walking will result in highly concentrated aerosols intruding into the buffer room from the ward, challenging the control of virus transmission risk. In this work, airflow exchange and bioaerosol particle transport between the negative-pressure isolation ward and the buffer room under dynamic scenarios were studied by transient computational fluid mechanics (CFD) simulation, thereby the fate of particles was divided into invasion stage and decay stage. The effects of ventilation pattern and HCW location on the concentration level and attenuation trend of particles were quantitatively analyzed. The results showed that increasing the HCW walking distance could increase the peak particle concentration within the buffer room by 4.5 % during the invasion stage. The effect of the buffer room ventilation layout on air exchange and particle transport was more pronounced than the HCW stay position. In the decay stage, the two more effective ventilation layouts could decrease the complete clearance time of particles and the particle concentration in the breathing zone by 31 % and 42 %, respectively. To reduce the infection risk, bioaerosol levels need to be reduced both in the buffer room and in the HCW breathing zone.

Hybrid vibration isolator based on piezoelectric actuator and metal rubber and its adaptive control method

To achieve vibration isolation across the entire working frequency range, this paper proposes a novel hybrid vibration isolator combining metal rubber and piezoelectric actuators, along with an adaptive active control algorithm. The passive isolation system allows for manual adjustment of stiffness and damping based on the preload, overcoming the issue of fixed stiffness and damping in traditional passive isolation units. For the active isolation system, an improved Filtered-x Normalized Least Mean Squares with adaptive step size active control algorithm is proposed, overcoming the problem of narrow frequency range applicability in traditional active control algorithms. A hybrid model of electromechanical coupling and hysteresis for the piezoelectric actuator is developed for the secondary path in the algorithm. Experimental results confirm that the hybrid isolator possesses vibration isolation capabilities within the 5–500 Hz working frequency range, with vibration suppression at the first and second resonance frequencies improved by 98.9% and 92.2%, respectively, compared to the passive system. Additionally, the hybrid isolator effectively suppresses complex multifrequency signals and demonstrates robustness and adaptability. This research provides advanced technological means to address complex vibration problems, and establishes both theoretical and practical foundations for multi-degree-of-freedom vibration isolation.