Demographic, Virological Characteristics and Prognosis of Asymptomatic COVID-19 Patients in South China.

BACKGROUND: Asymptomatic transmission is a major concern for SARS-CoV-2 community spread; however, little information is available on demographic, virological characteristics and prognosis of asymptomatic cases. METHODS: All COVID-19 patients hospitalized in Guangdong Province from September 1, 2020 to February 28, 2021, were included and were divided into asymptomatic and symptomaticgroup. The source country of all patients, clinical laboratory test results, the genotype of virus and the time of SARS-CoV-2 RNA turning negative or hospitalization were confirmed. RESULTS: Total 233 patients from 57 different countries or regions were included, with 83 (35.6%) asymptomatic and 150 (64.4%) symptomatic patients. Asymptomatic cases were younger (P = 0.019), lower rate in comorbidities (P = 0.021) such as hypertension (P = 0.083) and chronic liver disease (P = 0.045), lower PCT (P = 0.021), DDI (P < 0.001) and ALT (P = 0.029), but higher WBC count (P = 0.002) and lymphocyte (P = 0.011) than symptomatic patients. As for SARS-CoV-2 subtypes, patients infected with B.1.1 (53.8%), B.1.351 (81.8%) and B.1.524 (60%) are mainly asymptomatic, while infected with B, B.1, B.1.1.63, B.1.1.7, B.1.36, B.1.36.1, B.1.36.16, B.1.5 and B.6 were inclined to be symptomatic. Patients infected with variant B.1.351 and B.1.524 spent longer time in SARS-CoV-2 RNA turn negative (26 days, P = 0.085; 41 days, P = 0.007) and hospitalization (28 days, P = 0.085; 43 days, P = 0.004). CONCLUSIONS: The asymptomatic cases are prone to develop in patients with younger age, less comorbidities andinfected with B.1.1 and B.1.524 variants. More attention should be paid for lineage B.1.524 because it can significantly prolong the SARS-CoV-2 RNA negative conversion time and hospitalization in infected cases.

Risk assessment of airborne COVID-19 exposure in social settings.

The COVID-19 pandemic has led to many countries oscillating between various states of lock-down as they seek to balance keeping the economy and essential services running and minimizing the risk of further transmission. Decisions are made about which activities to keep open across a range of social settings and venues guided only by ad hoc heuristics regarding social distancing and personal hygiene. Hence, we propose the dual use of computational fluid dynamic simulations and surrogate aerosol measurements for location-specific assessment of risk of infection across different real-world settings. We propose a 3-tiered risk assessment scheme to facilitate classification of scenarios into risk levels based on simulations and experiments. Threshold values of <54 and >840 viral copies and <5% and >40% of original aerosol concentration are chosen to stratify low, medium, and high risk. This can help prioritize allowable activities and guide implementation of phased lockdowns or re-opening. Using a public bus in Singapore as a case study, we evaluate the relative risk of infection across scenarios such as different activities and passenger positions and demonstrate the effectiveness of our risk assessment methodology as a simple and easily interpretable framework. For example, this study revealed that the bus's air-conditioning greatly influences dispersion and increases the risk of certain seats and that talking can result in similar relative risk to coughing for passengers around an infected person. Both numerical and experimental approaches show similar relative risk levels with a Spearman's correlation coefficient of 0.74 despite differing observables, demonstrating applicability of this risk assessment methodology to other scenarios.

Effect of Emerging Major Infectious Diseases on Sleep Quality of Medical Workers: Findings from Medical Workers Providing Support During the COVID-19 Pandemic.

BACKGROUND The coronavirus disease 2019 (COVID-19) outbreak has exerted immense pressure on medical systems in China and abroad. This study aimed to compare the sleep quality of medical personnel conscripted to the Wuhan Union Cancer Centre to offer support during the early stages of the COVID-19 pandemic to the sleep quality of those who remained at Anhui Medical University Hospital and to determine the role of interventions in improving sleep quality. MATERIAL AND METHODS Questionnaires were completed by 369 individuals who were conscripted to support Wuhan (N=137) and others who were not (the control group; N=232). The Pittsburgh Sleep Quality Index (PSQI) was used to measure the duration and quality of sleep. The Anhui Provincial Health Commission organized a comprehensive intervention, consisting of physical-psychological-social dimensions, over the course of 2 weeks. RESULTS Only 34.21% of the Wuhan support workers reported better sleep quality, as opposed to the 55.60% of the control group at stage 1 (t/χ²=14.005, P<.001). Furthermore, despite the Wuhan support group being more prone to poor sleep quality, their sleep quality significantly improved after the interventions. CONCLUSIONS The findings from this study showed that medical staff who were conscripted to offer support during the early stages of the COVID-19 pandemic suffered from impaired quality of sleep. The use of questionnaire-based sleep assessments may provide individualized approaches to supporting medical personnel during future epidemics and pandemics. Furthermore, our results indicate that relevant interventions can significantly improve sleep quality, while a prolonged break after interventions does not affect sleep quality.

PTP-MEG2 regulates quantal size and fusion pore opening through two distinct structural bases and substrates.

Tyrosine phosphorylation of secretion machinery proteins is a crucial regulatory mechanism for exocytosis. However, the participation of protein tyrosine phosphatases (PTPs) in different exocytosis stages has not been defined. Here we demonstrate that PTP-MEG2 controls multiple steps of catecholamine secretion. Biochemical and crystallographic analyses reveal key residues that govern the interaction between PTP-MEG2 and its substrate, a peptide containing the phosphorylated NSF-pY83 site, specify PTP-MEG2 substrate selectivity, and modulate the fusion of catecholamine-containing vesicles. Unexpectedly, delineation of PTP-MEG2 mutants along with the NSF binding interface reveals that PTP-MEG2 controls the fusion pore opening through NSF independent mechanisms. Utilizing bioinformatics search and biochemical and electrochemical screening approaches, we uncover that PTP-MEG2 regulates the opening and extension of the fusion pore by dephosphorylating the DYNAMIN2-pY125 and MUNC18-1-pY145 sites. Further structural and biochemical analyses confirmed the interaction of PTP-MEG2 with MUNC18-1-pY145 or DYNAMIN2-pY125 through a distinct structural basis compared with that of the NSF-pY83 site. Our studies thus provide mechanistic insights in complex exocytosis processes.

Convalescent COVID-19 patients are susceptible to endothelial dysfunction due to persistent immune activation.

Numerous reports of vascular events after an initial recovery from COVID-19 form our impetus to investigate the impact of COVID-19 on vascular health of recovered patients. We found elevated levels of circulating endothelial cells (CECs), a biomarker of vascular injury, in COVID-19 convalescents compared to healthy controls. In particular, those with pre-existing conditions (e.g., hypertension, diabetes) had more pronounced endothelial activation hallmarks than non-COVID-19 patients with matched cardiovascular risk. Several proinflammatory and activated T lymphocyte-associated cytokines sustained from acute infection to recovery phase, which correlated positively with CEC measures, implicating cytokine-driven endothelial dysfunction. Notably, we found higher frequency of effector T cells in our COVID-19 convalescents compared to healthy controls. The activation markers detected on CECs mapped to counter receptors found primarily on cytotoxic CD8+ T cells, raising the possibility of cytotoxic effector cells targeting activated endothelial cells. Clinical trials in preventive therapy for post-COVID-19 vascular complications may be needed.

High expression of ACE2 receptor of 2019-nCoV on the epithelial cells of oral mucosa.

It has been reported that ACE2 is the main host cell receptor of 2019-nCoV and plays a crucial role in the entry of virus into the cell to cause the final infection. To investigate the potential route of 2019-nCov infection on the mucosa of oral cavity, bulk RNA-seq profiles from two public databases including The Cancer Genome Atlas (TCGA) and Functional Annotation of The Mammalian Genome Cap Analysis of Gene Expression (FANTOM5 CAGE) dataset were collected. RNA-seq profiling data of 13 organ types with para-carcinoma normal tissues from TCGA and 14 organ types with normal tissues from FANTOM5 CAGE were analyzed in order to explore and validate the expression of ACE2 on the mucosa of oral cavity. Further, single-cell transcriptomes from an independent data generated in-house were used to identify and confirm the ACE2-expressing cell composition and proportion in oral cavity. The results demonstrated that the ACE2 expressed on the mucosa of oral cavity. Interestingly, this receptor was highly enriched in epithelial cells of tongue. Preliminarily, those findings have explained the basic mechanism that the oral cavity is a potentially high risk for 2019-nCoV infectious susceptibility and provided a piece of evidence for the future prevention strategy in dental clinical practice as well as daily life.

Anesthetic Management of Patients with COVID 19 Infections during Emergency Procedures.

OBJECTIVES: The aim of the present study was to prevent cross-infection in the operating room during emergency procedures for patients with confirmed or suspected 2019 novel coronavirus (2019-nCoV) by following anesthesia management protocols, and to document clinical- and anesthesia-related characteristics of these patients. DESIGN: This was a retrospective, multicenter clinical study. SETTING: This study used a multicenter dataset from 4 hospitals in Wuhan, China. PARTICIPANTS: Patients and health care providers with confirmed or suspected 2019-nCoV from January 23 to 31, 2020, at the Wuhan Union Hospital, the Wuhan Children's Hospital, The Central Hospital of Wuhan, and the Wuhan Fourth Hospital in Wuhan, China. INTERVENTIONS: Anesthetic management and infection control guidelines for emergency procedures for patients with suspected 2019-nCoV were drafted and applied in 4 hospitals in Wuhan. MEASUREMENTS AND MAIN RESULTS: Cross-infection in the operating rooms of the 4 hospitals was effectively reduced by implementing the new measures and procedures. The majority of patients with laboratory-confirmed 2019-nCoV infection or suspected infection were female (23 [62%] of 37), and the mean age was 41.0 years old (standard deviation 19.6; range 4-78). 10 (27%) patients had chronic medical illnesses, including 4 (11%) with diabetes, 8 (22%) with hypertension, and 8 (22%) with digestive system disease. Twenty-five (68%) patients presented with lymphopenia, and 23 (62%) patients exhibited multiple mottling and ground-glass opacity on computed tomography scanning. CONCLUSIONS: The present study indicates that COVID 19-specific guidelines for emergency procedures for patients with confirmed or suspected 2019-nCoV may effectively prevent cross-infection in the operating room. Most patients with confirmed or suspected COVID 19 presented with fever and dry cough and demonstrated bilateral multiple mottling and ground-glass opacity on chest computed tomography scans.