PFC/M1 activation and excitability: a longitudinal cohort study on fatigue symptoms in healthcare workers post-COVID-19 (preprint)

Background Fatigue is one of the most common neurological symptoms reported post coronavirus disease 2019 (COVID-19) infection. In order to establish effective early intervention strategies, more emphasis should be placed on the correlation between fatigue and cortical neurophysiological changes, especially in healthcare workers, who are at a heightened risk of COVID-19 infection.Methods A prospective cohort study was conducted involving 29 COVID-19 medical workers and 24 healthy controls. The assessment included fatigue, sleep and health quality, psychological status, and physical capacity. Functional near-infrared spectroscopy (fNIRS) was employed to detect activation of brain regions. Bilateral primary motor cortex (M1) excitabilities were measured using single- and paired-pulse transcranial magnetic stimulation. Outcomes were assessed at 1, 3, and 6 months into the disease course.Results At 1-month post-COVID-19 infection, 37.9% of patients experienced severe fatigue symptoms, dropping to 10.3% at 3 months. Interestingly, the remarkable decreased activation/excitability of bilateral prefrontal lobe (PFC) and M1 were closely linked to fatigue symptoms after COVID-19. Notably, greater increase in M1 region excitability correlated with more significant fatigue improvement. Re-infected patients exhibited lower levels of brain activation and excitability compared to single-infection patients.Conclusions Both single infection and reinfection of COVID-19 lead to decreased activation and excitability of the PFC and M1. The degree of excitability improvement in the M1 region correlates with a greater recovery in fatigue. Based on these findings, targeted interventions to enhance and regulate the excitability of M1 may represent a novel strategy for COVID-19 early rehabilitation.Trial registration The Ethics Review Committee of Xijing Hospital, No. KY20232051-F-1, registered February 3, 2023. The Chinese Clinical Trial Registry, ChiCTR2300068444, registered February 20, 2023. https://www.chictr.org.cn

CD4+ T cell senescence is associated with reduced reactogenicity in severe/critical COVID-19 (preprint)

Background: Aging is a critical risk factor for unfavorable clinical outcomes among COVID-19 patients and may affect vaccine efficacy. However, whether the senescence of T cells impact the progression to severe COVID-19 in the elderly individuals remains unclear. Methods: By using flow cytometry, we analyzed the frequency of senescent T cells (Tsens) in the peripheral blood from 100 elderly patients hospitalized for COVID-19 and compared the difference between mild/moderate and severe/critical illness. We also assessed correlations between the percentage of Tsens and the quantity and quality of spike-specific antibodies by ELISA, neutralizing antibody test kit and Elispot assay respectively, cytokine production profile of COVID-19 reactive T cells as well as plasma soluble factors by cytometric bead array (CBA). Results: We found a significant elevated level of CD4+ Tsens in severe/critical disease compared to mild/moderate illness and patients with a higher level of CD4+ Tsens (>19.78%) showed a decreased survival rate as compared to those with a lower level (<19.78%), especially in the breakthrough infection. The percentage of CD4+ Tsens was negatively correlated with spike-specific antibody titers, neutralization ability and COVID-19 reactive IL-2+ CD4+ T cells. Additionally, IL-2 producing T cells and plasma levels of IL-2 were positively correlated with antibody levels. Conclusion: Our data illustrated that the percentage of CD4+ Tsens in the peripheral blood could act as an efficient biomarker for the capacity of spike-specific antibody production and the prognosis of severe COVID-19, especially in the breakthrough infection. Therefore, restoration of the immune response of CD4+ Tsens is one of the key factors to prevent severe illness and improve vaccine efficacy in older adults.

Research on the Design of Virtual Reality Online Education Information Presentation Based on Multi-Sensory Cognition

The popularity of the online teaching model increased during the COVID-19, and virtual reality online education is now firmly established as a future trend in educational growth. Human–computer interaction and collaboration between virtual models and physical entities, as well as virtual multi-sensory cognition, have become the focus of research in the field of online education. In this paper, we analyze the mapping form of teaching information and cue information on users' cognition through an experimental system and investigate the effects of the presentation form of online virtual teaching information, the length of the material, users' memory of the information, and the presentation form of information cues on users' cognitive performance. The experimental results show that different instructional information and cue presentation designs have significant effects on users' learning performance, with relatively longer instructional content being more effective and users being more likely to mechanically remember the learning materials. By studying the impact of multi-sensory information presentation on users' cognition, the output design of instructional information can be optimized, cognitive resources can be reasonably allocated, and learning effectiveness can be ensured, which is of great significance for virtual education research in digital twins.

Factors Associated with Adherence to Provider Referrals for Lung Cancer Screening with Low Dose Computed Tomography: Pre- and Post-COVID-19 Analysis (preprint)

Background Lung cancer has been the leading cause of American deaths from cancer. Although Medicare started covering lung cancer screening (LCS) with low-dose computed tomography (LDCT) in 2015, the uptake of LDCT-LCS remains low. This study examines the changes in adherence to provider referrals for LDCT-LCS and the factors at patient, provider, and health system levels that influence the completion rate of LDCT-LCS orders before and during the COVID-19 pandemic.Methods Our study examined electronic health record data (December 2013 - December 2020) from a large, community-based clinical healthcare delivery system in California. We plotted monthly trends in the frequency of LDCT-LCS orders and completion rate and compared the annual LDCT-LCS completion rate between LCS-eligible and LCS-ineligible groups. We then explored multilevel factors associated with the completion of LDCT-LCS orders using hierarchical generalized linear models.Results There was an increase in LDCT-LCS orders (N = 12,469) from 2013 to 2019, followed by a sharp decline in March 2020 due to the onset of the COVID-19 pandemic. Thereafter, LDCT-LCS orders slowly increased again in June 2020. The completion rate of LDCT-LCS increased from 0% in December 2013 to approximately 70% in 2018–2019 but declined to 50–60% in 2020 during the pandemic. Ineligible patients had lower completion rates of LDCT-LCS. Patients who were new to the healthcare system, Black, received the LDCT-LCS order in the first few years after Medicare coverage (2016 or 2017), during the pandemic, had major comorbidities, and smoked less than 30 pack-years were less likely to complete an order. Patients were more likely to complete LDCT-LCS orders if they were younger, received the LDCT-LCS order from a physician (vs. nonphysician provider), from family medicine or other specialties (vs. internal medicine), or saw a provider with more experience in LDCT-LCS.Conclusions The beginning of the COVID-19 pandemic largely decreased the volume of LDCT-LCS orders, but rates have since been slowing recovering. Future interventions to improve lung cancer screening should consider doing more targeted outreach to new patients and Black patients as well as providing additional education to nonphysician practitioners and those providers with lower rates of LDCT-LCS referral orders.

Predictors of Survival after Vaccination in a Pneumonic Plague Model.

Background: The need for an updated plague vaccine is highlighted by outbreaks in endemic regions together with the pandemic potential of this disease. There is no easily available, approved vaccine. Methods: Here we have used a murine model of pneumonic plague to examine the factors that maximise immunogenicity and contribute to survival following vaccination. We varied vaccine type, as either a genetic fusion of the F1 and V protein antigens or a mixture of these two recombinant antigens, as well as antigen dose-level and formulation in order to correlate immune response to survival. Results: Whilst there was interaction between each of the variables of vaccine type, dose level and formulation and these all contributed to survival, vaccine formulation in protein-coated microcrystals (PCMCs) was the key contributor in inducing antibody titres. From these data, we propose a cut-off in total serum antibody titre to the F1 and V proteins of 100 µg/mL and 200 µg/mL, respectively. At these thresholds, survival is predicted in this murine pneumonic model to be >90%. Within the total titre of antibody to the V antigen, the neutralising antibody component correlated with dose level and was enhanced when the V antigen in free form was formulated in PCMCs. Antibody titre to F1 was limited by fusion to V, but this was compensated for by PCMC formulation. Conclusions: These data will enable clinical assessment of this and other candidate plague vaccines that utilise the same vaccine antigens by identifying a target antibody titre from murine models, which will guide the evaluation of clinical titres as serological surrogate markers of efficacy.

Broad neutralization against SARS-CoV-2 variants induced by a modified B.1.351 protein-based COVID-19 vaccine candidate (preprint)

Beginning in late 2020, the emergence and spread of multiple variant SARS-CoV-2 strains harboring mutations which may enable immune escape necessitates the rapid evaluation of second generation COVID-19 vaccines, with the goal of inducing optimized immune responses that are broadly protective. Here we demonstrate in a mouse immunogenicity study that two doses of a modified B.1.351 spike (S)-Trimer vaccine (B.1.351 S-Trimer) candidate can induce strong humoral immune responses that can broadly neutralize both the original SARS-CoV-2 strain (Wuhan-Hu-1) and Variants of Concern (VOCs), including the UK variant (B.1.1.7), South African variant (B.1.351) and Brazil variant (P.1). Furthermore, while immunization with two doses (prime-boost) of Prototype S-Trimer vaccine (based on the original SARS-CoV-2 strain) induced lower levels of cross-reactive neutralization against the B.1.351 variant, a third dose (booster) administered with either Prototype S-Trimer or B.1.351 S-Trimer was able to increase neutralizing antibody titers against B.1.351 to levels comparable to neutralizing antibody titers against the original strain elicited by two doses of Prototype S-Trimer.

Preliminary study on environmental and climatic characteristics of historical infectious diseases and some thoughts of COVID-19

The outbreak and pandemic of COVID-19 pose a serious threat to the safety of human society and examine the ability of public health care resources around the world to deal with the large sudden infectious diseases. A review on the environmental and climatic characteristics related to historical infectious diseases will shed immediate light on the scientific research and control of COVID-19. Our results show that:(1) Historically, outbreaks of human-to-human coronavirus and orthomyxoviridae infectious diseases mainly occurred in the subtropical monsoon climate of the northern hemisphere in the winter and spring, while the outbreaks of flaviridae infectious diseases mostly occurred in tropical regions in hot and rainy summer and autumn.(2) Global warming and extreme weather may exacerbate the outbreak and spread of infectious diseases.(3) The impact of human activities on the ecosystem balance forces the habitat migration of virus hosts and the aggregation of different virus hosts, increasing the probability of virus mutation and the risk of infectious disease outbreaks. The lessons from historical outbreak of infectious diseases suggest that suitable climate factors might be conducive to the outbreak and epidemics, while the outbreaks in tropical countries also indicate that it is necessary to scrutinize the roles of climate, environmental conditions and ecological factors in the global wave of COVID-19. Our study provides some useful insights for the prevention and control of COVID-19 plague and other potential pandemics in the future.

Human Identical Sequences of SARS-CoV-2 Promote Clinical Progression of COVID-19 by Upregulating Hyaluronan via NamiRNA-Enhancer Network (preprint)

The COVID-19 pandemic is a widespread and deadly public health crisis. The pathogen SARS-CoV-2 replicates in the lower respiratory tract and causes fatal pneumonia. Although tremendous efforts have been put into investigating the pathogeny of SARS-CoV-2, the underlying mechanism of how SARS-CoV-2 interacts with its host is largely unexplored. Here, by comparing the genomic sequences of SARS-CoV-2 and human, we identified five fully conserved elements in SARS-CoV-2 genome, which were termed as "human identical sequences (HIS)". HIS are also recognized in both SARS-CoV and MERS-CoV genome. Meanwhile, HIS-SARS-CoV-2 are highly conserved in the primate. Mechanically, HIS-SARS-CoV-2 RNA directly binds to the targeted loci in human genome and further interacts with host enhancers to activate the expression of adjacent and distant genes, including cytokines gene and angiotensin converting enzyme II (ACE2), a well-known cell entry receptor of SARS-CoV-2, and hyaluronan synthase 2 (HAS2), which further increases hyaluronan formation. Noteworthily, hyaluronan level in plasma of COVID-19 patients is tightly correlated with severity and high risk for acute respiratory distress syndrome (ARDS) and may act as a predictor for the progression of COVID-19. HIS antagomirs, which downregulate hyaluronan level effectively, and 4-Methylumbelliferone (MU), an inhibitor of hyaluronan synthesis, are potential drugs to relieve the ARDS related ground-glass pattern in lung for COVID-19 treatment. Our results revealed that unprecedented HIS elements of SARS-CoV-2 contribute to the cytokine storm and ARDS in COVID-19 patients. Thus, blocking HIS-involved activating processes or hyaluronan synthesis directly by 4-MU may be effective strategies to alleviate COVID-19 progression.

S-Trimer, a COVID-19 subunit vaccine candidate, induces protective immunity in nonhuman primates (preprint)

SARS-CoV-2 is the underlying cause for the COVID-19 pandemic. Like most enveloped RNA viruses, SARS-CoV-2 uses a homotrimeric surface antigen to gain entry into host cells. Here we describe S-Trimer, a native-like trimeric subunit vaccine candidate for COVID-19 based on Trimer-Tag technology. Immunization of S-Trimer with either AS03 (oil-in-water emulsion) or CpG 1018 (TLR9 agonist) plus alum adjuvants induced high-levels of neutralizing antibodies and Th1-biased cellular immune responses in animal models. Moreover, rhesus macaques immunized with adjuvanted S-Trimer were protected from SARS-CoV-2 challenge compared to vehicle controls, based on clinical observations and reduction of viral loads in lungs. Trimer-Tag may be an important new platform technology for scalable production and rapid development of safe and effective subunit vaccines against current and future emerging RNA viruses.

Cryo-EM structure of S-Trimer, a subunit vaccine candidate for COVID-19 (preprint)

Less than a year after its emergence, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected over 22 million people worldwide with a death toll approaching 1 million. Vaccination remains the best hope to ultimately put this pandemic to an end. Here, using Trimer-Tag technology, we produced both wild-type (WT) and furin site mutant (MT) S-Trimers for COVID-19 vaccine studies. Cryo-EM structures of the WT and MT S-Trimers, determined at 3.2 Angstrom and 2.6 Angstrom respectively, revealed that both antigens adopt a tightly closed conformation and their structures are essentially identical to that of the previously solved full-length WT S protein in detergent. These results validate Trimer-Tag as a platform technology in production of metastable WT S-Trimer as a candidate for COVID-19 subunit vaccine.

Prevalence and clinical features of 2019 novel coronavirus disease (COVID-19) in the Fever Clinic of a teaching hospital in Beijing: a single-center, retrospective study (preprint)

Background With the spread of COVID-19 from Wuhan, Hubei Province to other areas of the country, medical staff in Fever Clinics faced the challenge of identifying suspected cases among patients with respiratory infections manifested with fever. We aimed to describe the prevalence and clinical features of COVID-19 as compared to pneumonias of other etiologies in a Fever Clinic in Beijing. Methods In this single-center, retrospective study, 342 cases of pneumonia were diagnosed in Fever Clinic in Peking University Third Hospital between January 21 to February 15, 2020. From these patients, 88 were reviewed by panel discussion as possible or probable cases of COVID-19, and received 2019-nCoV detection by RT-PCR. COVID-19 was confirmed by positive 2019-nCoV in 19 cases, and by epidemiological, clinical and CT features in 2 cases (the COVID-19 Group, n=21), while the remaining 67 cases served as the non-COVID-19 group. Demographic and epidemiological data, symptoms, laboratory and lung CT findings were collected, and compared between the two groups. Findings The prevalence of COVID-19 in all pneumonia patients during the study period was 6.14% (21/342). Compared with the non-COVID-19 group, more patients with COVID-19 had an identified epidemiological history (90.5% versus 32.8%, P<0.001). The COVID-19 group had lower WBC [5.19x10^9/L ({+/-}1.47) versus 7.21x10^9/L ({+/-}2.94), P<0.001] and neutrophil counts [3.39x10^9/L ({+/-}1.48) versus 5.38x10^9/L ({+/-}2.85), P<0.001] in peripheral blood. However, the percentage and count of lymphocytes were not different. On lung CT scans, involvement of 4 or more lobes was more common in the COVID-19 group (45% versus 16.4%, P=0.008). Interpretation In the period of COVID-19 epidemic outside Hubei Province, the prevalence of COVID-19 in patients with pneumonia visiting to our Fever Clinic in Beijing was 6.14%. Epidemiological evidence was important for prompt case finding, and lower blood WBC and neutrophil counts may be useful for differentiation from pneumonia of other etiologies.

Reflections on Reducing Pathogens in Sludge in the Case of COVID-19 Epidemic

Based on the problem that the novel coronavirus (SARS-CoV-2) can enter the urban drainage system through the excretion of patients' faces into the sewer, the fate of infective viruses in the urban water cycle was analyzed. Then, it was concluded that attention should be paid to the risk of virus spreading through sludge after the virus enters the urban drainage system. In the case of COVID-19 epidemic, it is impartant to summarize and reflect on the pathogen control during sludge treatment and disposal process in China. Therefore, the relevant standards and policies of sludge sterilization and disinfection in China have been systematically combed, and the relevant research results of the United States and the European Union have been studied. It has been considered that the sludge is a good carrier of pathogens;the standard restrictions on pathogens in sludge in our country are relatively loose currently. So it is necessary to strengthen the experiments and research on inactivation of pathogens in sludge, and to formulate the index and limit value of pathogens. The SARS-CoV-2 is an enveloped virus that can be relatively easily killed by antivirus agent. Therefore, adding disinfectant to the sludge pretreatment section is an effective measure to control pathogens during the epidemic. Aerobic fermentation, anaerobic digestion, lime stabilization, thermal drying, and radiation treatment can effectively reduce pathogens. During the epidemic period, sludge disposal methods are recommended to adopt incineration or co-incineration. For areas where the harmless disposal capacity of sludge is insufficient, the implementation of compliance sludge disposal outlet should be promoted. In addition, in order to reduce the exposure risk, in the sludge treatment and disposal process, the better sealing device should be preferred.