Structural bioinformatics analysis of SARS-CoV-2 variants reveals higher hACE2 receptor binding affinity for Omicron B.1.1.529 spike RBD compared to wild type reference.

To date, more than 263 million people have been infected with SARS-CoV-2 during the COVID-19 pandemic. In many countries, the global spread occurred in multiple pandemic waves characterized by the emergence of new SARS-CoV-2 variants. Here we report a sequence and structural-bioinformatics analysis to estimate the effects of amino acid substitutions on the affinity of the SARS-CoV-2 spike receptor binding domain (RBD) to the human receptor hACE2. This is done through qualitative electrostatics and hydrophobicity analysis as well as molecular dynamics simulations used to develop a high-precision empirical scoring function (ESF) closely related to the linear interaction energy method and calibrated on a large set of experimental binding energies. For the latest variant of concern (VOC), B.1.1.529 Omicron, our Halo difference point cloud studies reveal the largest impact on the RBD binding interface compared to all other VOC. Moreover, according to our ESF model, Omicron achieves a much higher ACE2 binding affinity than the wild type and, in particular, the highest among all VOCs except Alpha and thus requires special attention and monitoring.

Guidelines for COVID-19 Laboratory Testing for Emergency Departments From the New Diagnostic Technology Team of the Taiwan Society of Emergency Medicine

COVID-19 tests have different turnaround times (TATs), accuracy levels, and limitations, which emergency physicians should be aware of. Nucleic acid amplification tests (NAATs) can be divided into standard high throughput tests and rapid molecular diagnostic tests at the point of care (POC). The standard NAAT has the advantages of high throughput and high accuracy with a TAT of 3–4 hours. The POC molecular test has the same advantages of high accuracy as standard high throughput PCR, but can be done in 13–45 minutes. Roche cobas Liat is the most commonly used machine in Taiwan, displaying 99%–100% sensitivity and 100% specificity, respectively. Abbott ID NOW is an isothermal PCR-based POC machine with a sensitivity of 79% and a specificity of 100%. A high rate of false positives and false negatives is associated with rapid antigen testing. Antibody testing is mostly used as part of public health surveys and for testing for immunity.

Triage policy to postpone endoscopy for patients with low-risk varices is safe during the COVID-19 pandemic (preprint)

During the COVID-19 pandemic, most of the endoscopic services were electively postponed or suspended. We aimed to assess the safety of a triage policy in patients receiving esophageal variceal ligation during the COVID-19 pandemic. Triage policy of endoscopic variceal ligation (EVL) was implemented in our hospital during the lockdown period from 15th May 2021 to 26th July 2021. We compared the clinical characteristics and outcomes with those receiving endoscopy due to esophageal varices from 17th May 2020 to 28th July 2020. Of the 124 patients receiving EVL, a higher percentage of esophageal variceal bleeding (EVB) was noted (9/32, 28.1% vs. 8/92, 8.7%, p = 0.006) during the lockdown period, with a higher percentage of EVB in the referrals (7/9, 77.8% vs. 2/14, 14.2%, p = 0.007). Twenty-three patients whose endoscopies were postponed by triage policy due to low-risk or eradicated varices did not experience EVB during the lockdown period. Child-Pughs class C was independent factor predictive of EVB (relative risk 7.674, P = 0.004), entering the program of prophylactic EVL was the protective factor of EVB (relative risk 0.158, P = 0.004). Entrance into the prophylaxis program does not only decrease risk of EVB but also fosters comprehensive triage to postpone endoscopy during the lockdown period.

Structural Relationships among Online Community Use, Parental Stress, Social Support, and Quality of Life between Korean and Taiwanese Employed Mothers

This study examined mothers’ online community (OC) use and its structural relationship with parental stress, social support, and quality of life (QoL) under the social perspective of leisure and the theory of social support as a stress buffer. The population comprised employed mothers in two countries, Korea and Taiwan, which constitute appropriate settings for cross-cultural comparisons in the context of mothers’ OC use. The online questionnaire was distributed to 12 Korean mothers’ OCs and 14 Taiwanese mothers’ OCs, targeting employed mothers who have at least one child under seven-years-old and access mothers’ OCs on a regular basis. A total of 232 Korean and 303 Taiwanese responses were analyzed to examine the structural relationships among four key variables using structural equation modelling in AMOS 20. This study confirms that more parental stress leads to worse QoL. However, more parental stress results in less frequent participation in OCs, and OC use exerts a negative influence on QoL, which contradicts the hypothesized positive correlations. In comparison among Korean and Taiwanese mothers, Korean respondents showed a stronger influence of parental stress to mobilize more social support than did Taiwanese. This multidisciplinary study contributes to expanding the literature in noncommercial OCs, employed mothers in online leisure, and online social support in cross-cultural settings to promote the sustainability of families’ wellbeing.

Effect of e-learning environmental stimuli on learning engagement in the context of COVID-19

The epidemic of COVID-19 since the beginning of 2020 has brought changes in the conventional learning model to numerous students at school around the world, making e-learning at home a new trend. In this paper, the subject of Chinese college students is taken and SOR model which includes stimulus, organism and response, is adopted. The relationship among peer referent, perceived closeness and perceived control and the learning engagement has been examined in this paper. Data from 377 college students involved in e-learning is adopted, which indicates that perceived closeness, perceived control and peer referents in e-learning positively impact the self-efficacy and well-being of students, then students’ enthusiasm for learning has been enhanced. We aim to provide assistance to investigators, designers, instructors and someone else when they determine efficient ways of conceptualizing and measuring the involvement of students in e-learning

Chest CT Images for COVID-19: Radiologists and Computer-based detection (preprint)

Background Characteristic chest computed tomography (CT) manifestation of 2019 novel coronavirus (COVID-19) was added as a diagnostic criterion in the Chinese National COVID-19 management guideline. Whether the characteristic findings of Chest CT could differentiate confirmed COVID-19 cases from other positive nucleic acid test (NAT)-negative patients has not been rigorously evaluated. Purpose We aim to test whether chest computed tomography (CT) manifestation of 2019 novel coronavirus (COVID-19) can be differentiated by a radiologist or a computer-based CT image analysis system. Methods We conducted a retrospective case-control study that included 52 laboratory-confirmed COVID-19 patients and 80 non-COVID-19 viral pneumonia patients between 20 December, 2019 and 10 February, 2020. The chest CT images were evaluated by radiologists in a double blind fashion. A computer-based image analysis system (uAI system, Lianying Inc., Shanghai, China) detected the lesions in 18 lung segments defined by Boyden classification system and calculated the infected volume in each segment. The number and volume of lesions detected by radiologist and computer system was compared with Chi-square test or Mann-Whitney U test as appropriate. Results The main CT manifestations of COVID-19 were multi-lobar/segmental peripheral ground-glass opacities and patchy air space infiltrates. The case and control groups were similar in demographics, comorbidity, and clinical manifestations. There was no significant difference in eight radiologist identified CT image features between the two groups of patients. There was also no difference in the absolute and relative volume of infected regions in each lung segment. Conclusions We documented the non-differentiating nature of initial chest CT image between COVID-19 and other viral pneumonia with suspected symptoms. Our results do not support CT findings replacing microbiological diagnosis as a critical criterion for COVID-19 diagnosis. Our findings may prompt re-evaluation of isolated patients without laboratory confirmation.

Correlation of population mortality of COVID-19 and testing coverage: a comparison among 36 OECD countries and Taiwan (preprint)

Although testing is widely regarded as critical to fighting the Covid-19 pandemic, what measure and level of testing best reflects successful infection control remains unresolved. Our aim was to compare the sensitivity of two testing metrics-population testing number and testing coverage-to population mortality outcomes and identify a benchmark for testing adequacy with respect to population mortality and capture of potential disease burden. This ecological study aggregated publicly available data through April 12 on testing and outcomes related to COVID-19 across 36 OECD (Organization for Economic Development) countries and Taiwan. All OECD countries and Taiwan were included in this population-based study as a proxy for countries with highly developed economic and healthcare infrastructure. Spearman correlation coefficients were calculated between the aforementioned metrics and following outcome measures: deaths per 1 million people, case fatality rate, and case proportion of critical illness. Fractional polynomials were used to generate scatter plots to model the relationship between the testing metrics and outcomes. Testing coverage, but not population testing number, was highly correlated with population mortality (rs= -0.79, P=5.975e-09 vs rs = - 0.3, P=0.05) and case fatality rate (rs= -0.67, P=9.067e-06 vs rs= -0.21, P=0.20). A testing coverage threshold of 15-45 signified adequate testing: below 15, testing coverage was associated with exponentially increasing population mortality, whereas above 45, increased testing did not yield significant incremental mortality benefit. Testing coverage was better than population testing number in explaining country performance and can be used as an early and sensitive indicator of testing adequacy and disease burden. This may be particularly useful as countries consider re-opening their economies.

A Cascaded Learning Strategy for Robust COVID-19 Pneumonia Chest X-Ray Screening (preprint)

We introduce a comprehensive screening platform for the COVID-19 (a.k.a., SARS-CoV-2) pneumonia. The proposed AI-based system works on chest x-ray (CXR) images to predict whether a patient is infected with the COVID-19 disease. Although the recent international joint effort on making the availability of all sorts of open data, the public collection of CXR images is still relatively small for reliably training a deep neural network (DNN) to carry out COVID-19 prediction. To better address such inefficiency, we design a cascaded learning strategy to improve both the sensitivity and the specificity of the resulting DNN classification model. Our approach leverages a large CXR image dataset of non-COVID-19 pneumonia to generalize the original well-trained classification model via a cascaded learning scheme. The resulting screening system is shown to achieve good classification performance on the expanded dataset, including those newly added COVID-19 CXR images.