Recent advances in microbial synthesis of free heme

Heme is an iron-containing porphyrin compound widely used in the fields of healthcare, food, and medicine. Compared to animal blood extraction, it is more advantageous to develop a microbial cell factory to produce heme. However, heme biosynthesis in microorganisms is tightly regulated, and its accumulation is highly cytotoxic. The current review describes the biosynthetic pathway of free heme, its fermentation production using different engineered bacteria constructed by metabolic engineering, and strategies for further improving heme synthesis. Heme synthetic pathway in Bacillus subtilis was modified utilizing genome-editing technology, resulting in significantly improved heme synthesis and secretion abilities. This technique avoided the use of multiple antibiotics and enhanced the genetic stability of strain. Hence, engineered B. subtilis could be an attractive cell factory for heme production. Further studies should be performed to enhance the expression of heme synthetic module and optimize the expression of heme exporter and fermentation processes, such as iron supply. KEY POINTS: • Strengthening the heme biosynthetic pathway can significantly increase heme production. • Heme exporter overexpression helps to promote heme secretion, thereby further promoting excessive heme synthesis. • Engineered B. subtilis is an attractive alternative for heme production.

The combined effect of carbon starvation and exogenous riboflavin accelerated the Pseudomonas aeruginosa-induced nickel corrosion

The primary objective of this study is to elucidate the synergistic effect of an exogenous redox mediator and carbon starvation on the microbiologically influenced corrosion (MIC) of metal nickel (Ni) by nitrate reducing Pseudomonas aeruginosa. Carbon source (CS) starvation markedly accelerates Ni MIC by P. aeruginosa. Moreover, the addition of exogenous riboflavin significantly decreases the corrosion resistance of Ni. The MIC rate of Ni (based on corrosion loss volume) is ranked as: 10 % CS level + riboflavin > 100 % CS level + riboflavin > 10 % CS level > 100 % CS level. Notably, starved P. aeruginosa biofilm demonstrates greater aggressiveness in contributing to the initiation of surface pitting on Ni. Under CS deficiency (10 % CS level) in the presence of riboflavin, the deepest Ni pits reach a maximum depth of 11.2 μm, and the corrosion current density (icorr) peak at approximately 1.35 × 10-5 A·cm-2, representing a 2.6-fold increase compared to the full-strength media (5.25 × 10-6 A·cm-2). For the 10 % CS and 100 % CS media, the addition of exogenous riboflavin increases the Ni MIC rate by 3.5-fold and 2.9-fold, respectively. Riboflavin has been found to significantly accelerate corrosion, with its augmentation effect on Ni MIC increasing as the CS level decreases. Overall, riboflavin promotes electron transfer from Ni to P. aeruginosa, thus accelerating Ni MIC.

Both live and heat killed Lactiplantibacillus plantarum DPUL-F232 alleviate whey protein-induced food allergy by regulating cellular immunity and repairing the intestinal barrier

Postbiotics have been proposed as clinically viable alternatives to probiotics, addressing limitations and safety concerns associated with probiotic use. However, direct comparisons between the functional differences and health benefits of probiotics and postbiotics remain scarce. This study compared directly the desensitization effect of probiotics and postbiotics derived from Lactiplantibacillus plantarum strain DPUL-F232 in the whey protein-induced allergic rat model. The results demonstrate that administering both live and heat killed F232 significantly alleviated allergy symptoms, reduced intestinal inflammation, and decreased serum antibody and histamine levels in rats. Both forms of F232 were effective in regulating the Th1/Th2 balance, promoting the secretion of the regulatory cytokine IL-10, inhibiting mast cell degranulation and restoring the integrity of the intestinal barrier through the upregulation of tight junction proteins. Considering the enhanced stability and reduced safety concerns of postbiotics compared to probiotics, alongside their ability to regulate allergic reactions, we suggest that postbiotics may serve as viable substitutes for probiotics in managing food allergies and potentially other diseases.

Association between meteorological variations and the superspreading potential of SARS-CoV-2 infections

BACKGROUND

While many investigations examined the association between environmental covariates and COVID-19 incidence, none have examined their relationship with superspreading, a characteristic describing very few individuals disproportionally infecting a large number of people.

METHODS

Contact tracing data of all the laboratory-confirmed COVID-19 cases in Hong Kong from February 16, 2020 to April 30, 2021 were used to form the infection clusters for estimating the time-varying dispersion parameter (kt), a measure of superspreading potential. Generalized additive models with identity link function were used to examine the association between negative-log kt (larger means higher superspreading potential) and the environmental covariates, adjusted with mobility metrics that account for the effect of social distancing measures.

RESULTS

A total of 6,645 clusters covering 11,717 cases were reported over the study period. After centering at the median temperature, a lower ambient temperature at 10th percentile (18.2 °C) was significantly associated with a lower estimate of negative-log kt (adjusted expected change: -0.239 [95 % CI: -0.431 to -0.048]). While a U-shaped relationship between relative humidity and negative-log kt was observed, an inverted U-shaped relationship with actual vapour pressure was found. A higher total rainfall was significantly associated with lower estimates of negative-log kt.

CONCLUSIONS

This study demonstrated a link between meteorological factors and the superspreading potential of COVID-19. We speculated that cold weather and rainy days reduced the social activities of individuals minimizing the interaction with others and the risk of spreading the diseases in high-risk facilities or large clusters, while the extremities of relative humidity may favor the stability and survival of the SARS-CoV-2 virus.

Transmission risks of Omicron BA.5 following inactivated COVID-19 vaccines among children and adolescents in China

BACKGROUND

As SARS-CoV-2 Omicron variants circulating globally since 2022, assessing the transmission characteristics, and the protection of vaccines against emerging Omicron variants among children and adolescents are needed for guiding the control and vaccination policies.

METHODS

We conducted a retrospective cohort study for SARS-CoV-2 infections and close contacts aged <18 years from an outbreak seeded by Omicron BA.5 variants. The secondary attack rate (SAR) was calculated and the protective effects of two doses of inactivated vaccine (mainly Sinopharm /BBIBP-CorV) within a year versus one dose or two doses above a year after vaccination against the transmission and infection of Omicron BA.5 were estimated.

RESULTS

A total of 3442 all-age close contacts of 122 confirmed SARS-CoV-2 infections aged 0-17 years were included. The SAR was higher in the household setting and for individuals who received a one-dose inactivated vaccine or those who received a two-dose for more than one year, with estimates of 28.5% (95% credible interval [CrI]: 21.1, 37.7) and 55.3% (95% CrI: 24.4, 84.8), respectively. The second dose of inactivated vaccine conferred substantial protection against all infection and transmission of Omicron BA.5 variants within a year.

CONCLUSIONS

Our findings support the rollout of the second dose of inactivated vaccine for children and adolescents during the Omciron BA.5 predominant epidemic phase. Given the continuous emergence of SARS-CoV-2 variants, monitoring the transmission risk and corresponding vaccine effectiveness against SARS-CoV-2 variants among children and adolescents is important to inform control strategy.

A compact tri-notched flexible UWB antenna based on an inkjet-printable and plasma-activated silver nano ink

The rapid development of ultrawideband (UWB) communication systems has resulted in increasing performance requirements for the antenna system. In addition to a wide bandwidth, fast propagation rates and compact dimensions, flexibility, wearability or portability are also desirable for UWB antennas, as are excellent notch characteristics. Although progress has been made in the development of flexible/wearable antennas desired notch properties are still rather limited. Moreover, most presently available flexible UWB antennas are fabricated using environmentally not attractive subtractive etching-based processes. The usage of facile additive sustainably inkjet printing processes also utilizing low temperature plasma-activated conductive inks is rarely reported. In addition, the currently used tri-notched flexible UWB antenna designs have a relatively large footprint, which poses difficulties when integrated into miniaturized and compact communication devices. In this work, a silver nano ink is used to fabricate the antenna via inkjet printing and an efficient plasma sintering procedure. For the targeted UWB applications miniaturized tri-notched flexible antenna is realized on a flexible polyethylene terephthalate (PET) substrate with a compact size of 17.6 mm × 16 mm × 0.12 mm. The antenna operates in the UWB frequency band (2.9-10.61 GHz), and can shield interferences from WiMAX (3.3-3.6 GHz), WLAN (5.150-5.825 GHz) and X-uplink (7.9-8.4 GHz) bands, as well as exhibits a certain of bendability. Three nested "C" slots of different sizes were adopted to achieve notch features. The simulation and test results demonstrate that the proposed antenna can generate signal radiation in the desired UWB frequency band while retaining the desired notch properties and having acceptable SAR values on-body, making it a viable candidate for usage in flexible or wearable communication transmission devices. The research provides a facile and highly efficient method for fabricating flexible/wearable UWB antennas, that is, the effective combination of inkjet printing processing, flexible substrates, low temperature-activated conductive ink and antenna structure design.

Improving Surfactin Production in Bacillus subtilis 168 by Metabolic Engineering

Surfactin is widely used in the petroleum extraction, cosmetics, biopharmaceuticals and agriculture industries. It possesses antibacterial and antiviral activities and can reduce interfacial tension. Bacillus are commonly used as production chassis, but wild-type Bacillus subtilis 168 cannot synthesise surfactin. In this study, the phosphopantetheinyl transferase (PPTase) gene sfp* (with a T base removed) was overexpressed and enzyme activity was restored, enabling B. subtilis 168 to synthesise surfactin with a yield of 747.5 ± 6.5 mg/L. Knocking out ppsD and yvkC did not enhance surfactin synthesis. Overexpression of predicted surfactin transporter gene yfiS increased its titre to 1060.7 ± 89.4 mg/L, while overexpression of yerP, ycxA and ycxA-efp had little or negative effects on surfactin synthesis, suggesting YfiS is involved in surfactin efflux. By replacing the native promoter of the srfA operon encoding surfactin synthase with three promoters, surfactin synthesis was significantly reduced. However, knockout of the global transcriptional regulator gene codY enhanced the surfactin titre to 1601.8 ± 91.9 mg/L. The highest surfactin titre reached 3.89 ± 0.07 g/L, with the yield of 0.63 ± 0.02 g/g DCW, after 36 h of fed-batch fermentation in 5 L fermenter. This study provides a reference for further understanding surfactin synthesis and constructing microbial cell factories.

PIM1 alleviated liver oxidative stress and NAFLD by regulating the NRF2/HO-1/NQO1 pathway

AIMS

Non-alcoholic fatty liver disease (NAFLD) has risen as a significant global public health issue, for which vertical sleeve gastrectomy (VSG) has become an effective treatment method. The study sought to elucidate the processes through which PIM1 mitigates the advancement of NAFLD. The Pro-viral integration site for Moloney murine leukemia virus 1 (PIM1) functions as a serine/threonine kinase. Bioinformatics analysis revealed that reduced PIM1 expression in NAFLD.

METHODS

To further prove the role of PIM1 in NAFLD, an in-depth in vivo experiment was performed, in which male C57BL/6 mice were randomly grouped to receive a normal or high-fat diet for 24 weeks. They were operated or delivered the loaded adeno-associated virus which the PIM1 was overexpressed (AAV-PIM1). In an in vitro experiment, AML12 cells were treated with palmitic acid to induce hepatic steatosis.

KEY FINDINGS

The results revealed that the VSG surgery and virus delivery of mice alleviated oxidative stress, and apoptosis in vivo. For AML12 cells, the levels of oxidative stress, apoptosis, and lipid metabolism were reduced via PIM1 upregulation. Moreover, ML385 treatment resulted in the downregulation of the NRF2/HO-1/NQO1 signaling cascade, indicating that PIM1 mitigates NAFLD by targeting this pathway.

SIGNIFICANCE

PIM1 alleviated mice liver oxidative stress and NAFLD induced by high-fat diet by regulating the NRF2/HO-1/NQO1 signaling Pathway.

Association of nirmatrelvir-ritonavir with post-acute sequelae and mortality in patients admitted to hospital with COVID-19: a retrospective cohort study

BACKGROUND

Studies have established the short-term efficacy of nirmatrelvir-ritonavir in managing COVID-19, yet its effect on post-COVID-19 condition, especially in patients admitted to hospital, remains understudied. This study aimed to examine the effect of nirmatrelvir-ritonavir on post-COVID-19 condition among patients admitted to hospital in Hong Kong.

METHODS

This retrospective cohort study used real-world, territory-wide inpatient records, vaccination records, and confirmed COVID-19 case data from the Hong Kong Hospital Authority and Department of Health, The Government of the Hong Kong Special Administrative Region. Patients aged 18 years and older who tested positive for SARS-CoV-2 between March 11, 2022, and Oct 10, 2023, and who were admitted to hospital with COVID-19 were included. The treatment group included patients prescribed nirmatrelvir-ritonavir within 5 days of symptom onset, excluding those prescribed molnupiravir within 21 days, and the control group had no exposure to either nirmatrelvir-ritonavir or molnupiravir. The outcomes were post-acute inpatient death and 13 sequelae (congestive heart failure, atrial fibrillation, coronary artery disease, deep vein thrombosis, chronic pulmonary disease, acute respiratory distress syndrome, interstitial lung disease, seizure, anxiety, post-traumatic stress disorder, end-stage renal disease, acute kidney injury, and pancreatitis). These outcomes were evaluated starting at 21 days after the positive RT-PCR date in each respective cohort constructed for the outcome. Standardised mortality ratio weights were applied to balance covariates, and Cox proportional hazards regression was used to investigate the relationship between nirmatrelvir-ritonavir and outcomes.

FINDINGS

136 973 patients were screened for inclusion, among whom 50 055 were eligible and included in the analysis (24 873 [49·7%] were female and 25 182 [50·3%] were male). 15 242 patients were prescribed nirmatrelvir-ritonavir during acute COVID-19 and 23 756 patients were included in the control group; 11 057 patients did not meet our definition for the exposed and unexposed groups. Patients were followed up for a median of 393 days (IQR 317-489). In the nirmatrelvir-ritonavir group compared with the control group, there was a significantly lower hazard of post-acute inpatient death (hazard ratio 0·62 [95% CI 0·57-0·68]; p<0·0001), congestive heart failure (0·70 [0·58-0·85]; p=0·0002), atrial fibrillation (0·63 [0·52-0·76]; p<0·0001), coronary artery disease (0·71 [0·59-0·85]; p=0·0002), chronic pulmonary disease (0·68 [0·54-0·86]; p=0·0011), acute respiratory distress syndrome (0·71 [0·58-0·86]; p=0·0007), interstitial lung disease (0·17 [0·04-0·75]; p=0·020), and end-stage renal disease (0·37 [0·18-0·74]; p=0·0049). There was no evidence indicating difference between the groups in deep vein thrombosis, seizure, anxiety, post-traumatic stress disorder, acute kidney injury, and pancreatitis.

INTERPRETATION

This study showed extended benefits of nirmatrelvir-ritonavir for reducing the risk of post-acute inpatient death as well as cardiovascular and respiratory complications among patients admitted to hospital with COVID-19. Further research is essential to uncover the underlying mechanisms responsible for these observed negative associations and to devise effective strategies for preventing the onset of post-acute sequelae.

FUNDING

Health and Medical Research Fund, Research Grants Council theme-based research schemes, and Research Grants Council Collaborative Research Fund.

Synthesis of Unsymmetrical Trisulfides from S-Substituted Sulphenylthiosulphates

Trisulfide unit is widely found in natural products and has garnered attention due to the unique pharmacological and physiochemical properties. However, despite limited progress, widely applicable approaches for constructing unsymmetrical trisulfides have so far remain scarce. In this work, an easy-to-prepare, solid-state and scalable reagent, S-substituted sulphenylthiosulphate, has been developed for the divergent synthesis of unsymmetrical trisulfides. Alkyl electrophile substrates, including bromides, chlorides, iodides and tosylates, with diverse substituents are smoothly converted to the corresponding trisulfides with S-substituted sulphenylthiosulphates and thiourea as another sulfur source. Furthermore, the late-stage modification of drug molecules was successfully achieved through this method.

The effect of indoor air filtration on biomarkers of inflammation and oxidative stress: a review and meta-analysis of randomized controlled trials

Improvement of indoor air quality is beneficial for human health. However, previous studies have not reached consistent conclusions regarding the effects of indoor air filtration on inflammation and oxidative stress. This study aims to determine the relationship between indoor air filtration and inflammation and oxidative stress biomarkers. We conducted an electronic search that evaluated the association of indoor air filtration with biomarkers of inflammation and oxidative stress in five databases (PubMed, Cochrane Library, EMBASE, Web of Science, and Scopus) from the beginning to April 23, 2023. Outcomes included the following markers: interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), C-reactive protein (CRP), malondialdehyde (MDA), 8-hydroxy-2deoxyguanosine (8-OHdG), and 8-iso-prostaglandinF2α (8-isoPGF2α). We extracted data from the included studies according to the system evaluation and the preferred reporting item for meta-analysis (PRISMA) guidelines and used the Cochrane risk of bias tool to assess bias risk. Our meta-analysis included 15 studies with 678 participants to assess the combined effect size. The meta-analysis demonstrated that indoor air filtration could have a marked reduction in IL-6 (SMD: -0.275, 95% CI: -0.545 to -0.005, p = 0.046) but had no significant effect on other markers of inflammation or oxidative stress. Subgroup analysis results demonstrated a significant reduction in 8-OHdG levels in the subgroup with < 1 day of duration (SMD: -0.916, 95% CI: -1.513 to -0.320; p = 0.003) and using filtrete air filter (SMD: -5.530, 95% CI: -5.962 to -5.099; p < 0.001). Our meta-analysis results depicted that indoor air filtration can significantly reduce levels of inflammation and oxidative stress markers. Considering the adverse effects of air pollution on human health, our study provides powerful evidence for applying indoor air filtration to heavy atmospheric pollution.

A Sinh-Cosh-Enhanced DBO Algorithm Applied to Global Optimization Problems

The Dung beetle optimization (DBO) algorithm, devised by Jiankai Xue in 2022, is known for its strong optimization capabilities and fast convergence. However, it does have certain limitations, including insufficiently random population initialization, slow search speed, and inadequate global search capabilities. Drawing inspiration from the mathematical properties of the Sinh and Cosh functions, we proposed a new metaheuristic algorithm, Sinh-Cosh Dung Beetle Optimization (SCDBO). By leveraging the Sinh and Cosh functions to disrupt the initial distribution of DBO and balance the development of rollerball dung beetles, SCDBO enhances the search efficiency and global exploration capabilities of DBO through nonlinear enhancements. These improvements collectively enhance the performance of the dung beetle optimization algorithm, making it more adept at solving complex real-world problems. To evaluate the performance of the SCDBO algorithm, we compared it with seven typical algorithms using the CEC2017 test functions. Additionally, by successfully applying it to three engineering problems, robot arm design, pressure vessel problem, and unmanned aerial vehicle (UAV) path planning, we further demonstrate the superiority of the SCDBO algorithm.

High throughput automated characterization of enamel microstructure using synchrotron tomography and optical flow imaging

The remarkable damage-tolerance of enamel has been attributed to its hierarchical microstructure and the organized bands of decussated rods. A thorough characterization of the microscale rod evolution within the enamel is needed to elucidate this complex structure. While prior efforts in this area have made use of single particle tracking to track a single rod evolution to various degrees of success, such a process can be both computationally and labor intensive, limited to the evolution path of a single rod, and is therefore prone to error from potentially tracking outliers. Particle image velocimetry (PIV) is a well-established algorithm to derive field information from image sequences for processes that are time-dependent, such as fluid flows and structural deformation. In this work, we demonstrate the use of PIV in extracting the full-field microstructural distribution of rods within the enamel. Enamel samples from a wild African lion were analyzed using high-energy synchrotron X-ray micro-tomography. Results from the PIV analysis provide sufficient full-field information to reconstruct the growth of individual rods that can potentially enable rapid analysis of complex microstructures from high resolution synchrotron datasets. Such information can serve as a template for designing damage-tolerant bioinspired structures for advanced manufacturing. STATEMENT OF SIGNIFICANCE: Thorough characterization and analysis of biological microstructures (viz. dental enamel) allows us to understand the basis of their excellent mechanical properties. Prior efforts have successfully replicated these microstructures via single particle tracking, but the process is computationally and labor intensive. In this work, optical flow imaging algorithms were used to extract full-field microstructural distribution of enamel rods from synchrotron X-ray computed tomography datasets, and a field method was used to reconstruct the growth of individual rods. Such high throughput information allows for the rapid production/prototyping and advanced manufacturing of damage-tolerant bioinspired structures for specific engineering applications. Furthermore, the algorithms used herein are freely available and open source to broaden the availability of the proposed workflow to the general scientific community.

Synthesis of N-Difluoromethyl Carbonyl Compounds from N-Difluoromethylcarbamoyl Fluorides

Fluorinated small molecules are commonly used in functional small-molecule chemistry, and N-difluoromethyl (N-CF2H) compounds are particularly intriguing due to their unique and unexplored physiochemical properties. However, despite limited progress, a general methodological approach to the synthesis of N-CF2H compounds remains elusive. Here, guided by computation, we present a simple and practical protocol to access N-CF2H amides and related carbonyl derivatives. The protocol involves a one-pot conversion of thioformamides through desulfurization-fluorination and acylation, providing N-difluoromethylcarbamoyl fluoride building blocks that can be further diversified to a variety of unexplored N-CF2H carbonyl compounds with rich functionality. Additionally, preliminary studies on their properties and stability showcased their potential application in pharmaceuticals and agrochemicals.

Insight into the Types of Alkanolamines on the Properties of Copper(II) Formate-Based Conductive Ink

Conductive inks are one of the most important functional materials for printed flexible electronic devices, and their properties determine the methods of subsequent patterning and metallization. In comparison with copper nanoparticle or nanowire inks, copper particle-free inks employing copper(II) formate (Cuf) as a precursor have attracted the interest of researchers due to their flexibility in preparation, excellent stability, and lower conversion temperature. Alkanolamines can provide Cuf with excellent solubility in alcohols while being less toxic and having a certain reducibility, making them preferable ligands in comparison with aliphatic amines and pyridine. However, there have been few studies on the effects of the alkanolamine types on the performance of Cuf inks. Also, the decomposition mechanism of copper-alkanolamine complex inks is not clear. In this work, different kinds of alkanolamines were chosen as ligands to formulate Cuf inks to address the mentioned issues. The influences of amine types on the stability, wettability, thermal decomposition behavior, and electrical performance of the formulated Cuf particle-free inks were investigated in detail. The results show that the utilization of alkanolamines could provide Cuf with excellent solubility in alcohols, resulting in an ink with good stability and favorable wetting properties. The thermal decomposition temperature and electrical performance of the formulated copper ink are largely dependent on the amine used. When amines with a longer carbon chain and more branches were utilized to prepare the ink, a decreased decomposition temperature was observed on the derived inks because of the steric hindrance effect. Copper films with good morphology and conductivity could be obtained at low temperatures by selecting the appropriate alkanolamine. Copper particle-free conductive ink from 2-amino-2-methyl-1-propanol demonstrated better morphology and electrical performance (16.09 μΩ·cm) and was successfully used for conductive circuits by direct-writing.

A meta-analysis reveals increases in soil organic carbon following the restoration and recovery of croplands in Southwest China

In China, the Grain for Green Program (GGP) is an ambitious project to convert croplands into natural vegetation, but exactly how changes in vegetation translate into changes in soil organic carbon remains less clear. Here we conducted a meta-analysis using 734 observations to explore the effects of land recovery on soil organic carbon and nutrients in four provinces in Southwest China. Following GGP, the soil organic carbon content (SOCc) and soil organic carbon stock (SOCs) increased by 33.73% and 22.39%, respectively, compared with the surrounding croplands. Similarly, soil nitrogen increased, while phosphorus decreased. Outcomes were heterogeneous, but depended on variations in soil and environmental characteristics. Both the regional land use and cover change indicated by the landscape type transfer matrix and net primary production from 2000 to 2020 further confirmed that the GGP promoted the forest area and regional mean net primary production. Our findings suggest that the GGP could enhance soil and vegetation carbon sequestration in Southwest China and help to develop a carbon-neutral strategy.

All cause and cause specific mortality associated with transition to daylight saving time in US: nationwide, time series, observational study

Objectives

To estimate the association between the transition to daylight saving time and the risks of all cause and cause specific mortality in the US.

Design

Nationwide time series observational study based on weekly data.

Setting

US state level mortality data from the National Center for Health Statistics, with death counts from 50 US states and the District of Columbia, from the start of 2015 to the end of 2019.

Population

13 912 837 reported deaths in the US.

Main outcome measures

Weekly counts of mortality for any cause, and for Alzheimer's disease, dementia, circulatory diseases, malignant neoplasms, and respiratory diseases.

Results

During the study period, 13 912 837 deaths were reported. The analysis found no evidence of an association between the transition to spring daylight saving time (when clocks are set forward by one hour on the second Sunday of March) and the risk of all cause mortality during the first eight weeks after the transition (rate ratio 1.003, 95% confidence interval 0.987 to 1.020). Autumn daylight saving time is defined in this study as the time when the clocks are set back by one hour (ie, return to standard time) on the first Sunday of November. Evidence indicating a substantial decrease in the risk of all cause mortality during the first eight weeks after the transition to autumn daylight saving time (0.974, 0.958 to 0.990). Overall, when considering the transition to both spring and autumn daylight saving time, no evidence of any effect of daylight saving time on all cause mortality was found (0.988, 0.972 to 1.005). These patterns of changes in mortality rates associated with transition to daylight saving time were consistent for Alzheimer's disease, dementia, circulatory diseases, malignant neoplasms, and respiratory diseases. The protective effect of the transition to autumn daylight saving time on the risk of mortality was more pronounced in elderly people aged ≥75 years, in the non-Hispanic white population, and in those residing in the eastern time zone.

Conclusions

In this study, transition to daylight saving time was found to affect mortality patterns in the US, but an association with additional deaths overall was not found. These findings might inform the ongoing debate on the policy of shifting daylight saving time.

The role of endoplasmic reticulum stress-related genes in the diagnosis and subtyping of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent liver disease worldwide. Chronic activation of endoplasmic reticulum stress (ERS) in hepatocytes may promote the development of NAFLD, yet endoplasmic reticulum stress-related genes (ERSGs) have not been studied in NAFLD. Our aim is to study the relationship between ERSGs and the immune microenvironment of NAFLD patients and to construct predictive models. We screened 48 endoplasmic reticulum stress-related differentially expressed genes (ERSR-DEGs) using data from two GEO datasets and the GeneCards database. Enrichment analysis revealed that ERSR-DEGs are closely associated with immune-related pathways and functions. The immune infiltration profile of NAFLD was obtained by single sample gene set enrichment analysis (ssGSEA). There were significant differences in immune cell infiltration and immune function between NAFLD group and control group. Using 113 NAFLD samples, we explored two molecular clusters based on ERSR-DEGs. A five-gene SVM model was selected as the best machine learning model, and a nomogram based on five-gene SVM model showed good predictive efficiency. The mRNA expression levels of POR, PPP1R15A, FOS and FAS were significantly different between NAFLD mice and healthy mice. In conclusion, ERS is closely associated with the development of NAFLD. We established a promising and SVM-based predictive model to assess the risk of disease in patients with ERS subtypes and NAFLD.

A high-current hydrogel generator with engineered mechanoionic asymmetry

Mechanoelectrical energy conversion is a potential solution for the power supply of miniaturized wearable and implantable systems; yet it remains challenging due to limited current output when exploiting low-frequency motions with soft devices. We report a design of a hydrogel generator with mechanoionic current generation amplified by orders of magnitudes with engineered structural and chemical asymmetry. Under compressive loading, relief structures in the hydrogel intensify net ion fluxes induced by deformation gradient, which synergize with asymmetric ion adsorption characteristics of the electrodes and distinct diffusivity of cations and anions in the hydrogel matrix. This engineered mechanoionic process can yield 4 mA (5.5 A m-2) of peak current under cyclic compression of 80 kPa applied at 0.1 Hz, with the transferred charge reaching up to 916 mC m-2 per cycle. The high current output of this miniaturized hydrogel generator is beneficial for the powering of wearable devices, as exemplified by a controlled drug-releasing system for wound healing. The demonstrated mechanisms for amplifying mechanoionic effect will enable further designs for a variety of self-powered biomedical systems.

Integrating FRAM and BN for enhanced resilience evaluation in construction emergency response: A scaffold collapse case study

The construction system's complexity can generate substantial uncertainties during emergencies. Resilience, as a new perspective on emergency response, can significantly mitigate these challenges. This paper introduces an innovative model to assess the resilience of construction emergency response processes utilizing a scaffold collapse scenario as a demonstrative case study. Grounded in resilience engineering, our model integrates the merits of the Functional Resonance Analysis Method (FRAM) with the probabilistic strengths of Bayesian Networks (BNs). The process commences with FRAM, mapping out the emergency response in qualitative terms by identifying functions, variabilities, and couplings. This culminates in a topological network which serves as a foundational structure for the directed Complex Network (CN) and the BN model. Thereafter, the Delphi method and the modified K-shell (MKS) decomposition algorithm guide the computation of prior probabilities for root nodes and the conditional probability table within the BN model. Subsequently, the BN model is subjected to a simulation using the AgenaRisk software, executing both forward and backward propagation as well as sensitivity analyses. Our findings pinpoint "Intersectoral Coordination and Linkage" as the most crucial function, with rapidity being the most sensitive aspect influencing resilience during a scaffold collapse emergency response process.

Genome-wide association study identifies multiple loci influencing duck serum biochemical indicators in the laying period

1. Laying performance is an important economic trait in poultry. The blood is essential in transporting nutrients to the yolk and albumen and is necessary for egg formation.2. This study calculated the phenotypic relationships of duck egg quality, egg production efficiency and 22 serum parameters in the egg-laying stage. Using a variety of methodologies, a genome-wide association study (GWAS) was carried out to uncover the genetic foundations of the 22 serum biochemical markers of laying ducks.3. Spearman correlation coefficients between the egg production (226-329 per day) and the serum parameters were all weak, being less than 0.3. This analysis was done on 22 serum parameters, with total protein (TP), total triglycerides (TG), calcium (Ca) and phosphorous (P) having the highest correlation coefficients (r = 0.56-0.88). The coefficients for blood markers, such as total cholesterol (CHOL), total bilirubin (TBIL), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) varied from 0.70-0.94.4. Based on single-marker single-trait genome-wide analyses by a mixed linear model program of EMMAX, nine candidate genes were associated with enzyme traits (AST/ALT aspartate transaminase/glutamic-pyruvic transaminase, creatine kinase) and 19 candidate genes were associated with metabolism and protein-related serum parameters (glucose, total bile acid, uric acid (UA), albumin (ALB).5. The mvLMM (multivariate linear mixed model) of GEMMA software was used to carry out multiple trait integrated GWAS. Two candidate genes were found in the TP-TG-CA-P analysis and seven candidate genes in the CHOL_LDL-C_HDL-C_TBIL study. There was a high genetic correlation between the two groups.

Ion-Molecule Co-Confining Ammonium Vanadate Cathode for High-Performance Aqueous Zinc-Ion Batteries

Vanadium-based cathode materials have attracted great attention in aqueous zinc-ion batteries (AZIBs). However, the inferior ion transport and cyclic stability due to the strong Coulomb interaction between Zn2+ and the lattice limit their further application. In this work, CO2 molecules are in situ embedded in the interlayer structure of NH4 V4 O10 by decomposing excess H2 C2 O4 ·2H2 O in the main framework, obtaining an ion-molecule co-confining NH4 V4 O10 for AZIB cathode material. The introduced CO2 molecules expanded the interlayer spacing of NH4 V4 O10 , broadened the diffusion channel of Zn2+ , and stabilized the structure of NH4 V4 O10 as the interlayer pillars together withNH 4 + ${\mathrm{NH}}_4^ + $ , which effectively improved the Zn2+ diffusion kinetics and cycle stability of the electrode. In addition, the binding betweenNH 4 + ${\mathrm{NH}}_4^ + $ and the host framework is stabilized via hydrogen bonds with CO2 molecules. NVO-CO2 -0.8 exhibited excellent specific capacity (451.1 mAh g-1 at 2 A g-1 ), cycle stability (214.0 mAh g-1 at 10 A g-1 after 1000 cycles) and rate performance. This work provides new ideas and approaches for optimizing vanadium-based materials with high-performance AZIBs.

Impact of the surge of COVID-19 Omicron outbreak on the intention of seasonal influenza vaccination in Hong Kong: A cross-sectional study

OBJECTIVE

To assess the intention of influenza vaccination during the Omicron pandemic of COVID-19 via a structured cross-sectional survey.

METHODS

A cross-sectional study was conducted in 1,813 Hong Kong quota-sampled adults between March and September 2022, when Hong Kong was experiencing an outbreak of Omicron infections. Questions included self-reported medical and vaccination history, and perceptions and intention of influenza vaccine. A multiple logistic regression analysis was conducted to identify significant factors associated with the vaccination intention.

RESULTS

Of the 1,813 participants, 25.8% (95% CI: 23.8%-27.8%) perceived positive impact of COVID-19 pandemic on their influenza vaccine willingness, which was more than two times the proportion of those who feel less likely to take influenza vaccine (11.5%, 95% CI: 10.1%-13.1%). Compared with males, females were less likely to receive influenza vaccine for 2022-23 influenza seasons (OR = 0.71, 95% CI: 0.52-0.95, p = 0.023) and had less impact on their influenza vaccine willingness (OR = 0.76, 95% CI: 0.59-0.99, p = 0.043). Participants older than 60 years old were related to a less positive impact compared with the youngers (OR = 0.53, 95% CI: 0.30-0.93, p = 0.028). Participants with experience of influenza vaccine uptake also showed a higher intention of seasonal influenza vaccination.

CONCLUSION

The public intention of influenza vaccine has been raised in Hong Kong. With the identified subgroups (e.g., female and elderly) and reasons for being reluctant to the influenza vaccination, policy makers should rectify common misperceptions in order to increase influenza vaccination coverage at the post COVID-19 phase.

Astaxanthin alleviates PM2.5-induced cardiomyocyte injury via inhibiting ferroptosis

BACKGROUND

Long-term exposure of humans to air pollution is associated with an increasing risk of cardiovascular diseases (CVDs). Astaxanthin (AST), a naturally occurring red carotenoid pigment, was proved to have multiple health benefits. However, whether or not AST also exerts a protective effect on fine particulate matter (PM2.5)-induced cardiomyocyte damage and its underlying mechanisms remain unclear.

METHODS

In vitro experiments, the H9C2 cells were subjected to pretreatment with varying concentrations of AST, and then cardiomyocyte injury model induced by PM2.5 was established. The cell viability and the ferroptosis-related proteins expression were measured in different groups. In vivo experiments, the rats were pretreated with different concentrations of AST for 21 days. Subsequently, a rat model of myocardial PM2.5 injury was established by intratracheal instillation every other day for 1 week. The effects of AST on myocardial tissue injury caused by PM2.5 indicating by histological, serum, and protein analyses were examined.

RESULTS

AST significantly ameliorated PM2.5-induced myocardial tissue injury, inflammatory cell infiltration, the release of inflammatory factors, and cardiomyocyte H9C2 cell damage. Mechanistically, AST pretreatment increased the expression of SLC7A11, GPX4 and down-regulated the expression of TfR1, FTL and FTH1 in vitro and in vivo.

CONCLUSIONS

Our study suggest that ferroptosis plays a significant role in the pathogenesis of cardiomyocyte injury induced by PM2.5. AST may serve as a potential therapeutic agent for mitigating cardiomyocyte injury caused by PM2.5 through the inhibition of ferroptosis.

Functional Polythioamides Derived from Thiocarbonyl Fluoride

Polythioamide is a unique type of sulfur-containing polymer with advanced functionalities. Nonetheless, the elemental sulfur commonly used in their synthesis tends to react readily with unsaturated functional groups, thereby limiting the scope of eligible substrates. Inspired by the highly efficient sulfur-fluoride exchange (SuFEx) polymerization through discrete hubs, we present herein a pioneering and versatile approach to the synthesis of polythioamides from diboronic acids, secondary diamines, and thiocarbonyl fluoride as the central connective hub. Well-defined structures, including previously inaccessible unsaturated substrates, were realized. These newly devised polythioamides can efficiently and selectively bind to metal ions and were applied in precious-metal recovery. Further development resulted in PdII -crosslinked single-chain nanoparticles serving as recyclable homogeneous catalysts, thus demonstrating the vast potential of these unprecedented polythioamides. We anticipate that thiocarbonyl fluoride could emerge as a potent hub for facilitating the intricate synthesis of sulfur-containing polymers.

Effectiveness of the booster dose of inactivated COVID-19 vaccine against Omicron BA.5 infection: a matched cohort study of adult close contacts

BACKGROUND

Although COVID-19 vaccines and their booster regimens protect against symptomatic infections and severe outcomes, there is limited evidence about their protection against asymptomatic and symptomatic infections in real-world settings, particularly when considering that the majority of SARS-CoV-2 Omicron infections were asymptomatic. We aimed to assess the effectiveness of the booster dose of inactivated vaccines in mainland China, i.e., Sinopharm (BBIBP-CorV) and Sinovac (CoronaVac), against Omicron infection in an Omicron BA.5 seeded epidemic.

METHODS

Based on an infection-naive but highly vaccinated population in Urumqi, China, the study cohort comprised all 37,628 adults who had a contact history with individuals having SARS-CoV-2 infections, i.e., close contacts, between August 1 and September 7, 2022. To actively detect SARS-CoV-2 infections, RT-PCR tests were performed by local authorities on a daily basis for all close contacts, and a testing-positive status was considered a laboratory-confirmed outcome. The cohort of close contacts was matched at a ratio of 1:5 with the fully vaccinated (i.e., 2 doses) and booster vaccinated groups (i.e., 3 doses) according to sex, age strata, calendar date, and contact settings. Multivariate conditional logistic regression models were adopted to estimate the marginal effectiveness of the booster dose against Omicron BA.5 infection after adjusting for confounding variables. Subgroup analyses were performed to assess vaccine effectiveness (VE) in different strata of sex, age, the time lag from the last vaccine dose to exposure, and the vaccination status of the source case. Kaplan-Meier curves were employed to visualize the follow-up process and testing outcomes among different subgroups of the matched cohort.

FINDINGS

Before matching, 37,099 adult close contacts were eligible for cohort enrolment. After matching, the 2-dose and 3-dose groups included 3317 and 16,051 contacts, and the proportions with Omicron infections were 1.03% and 0.62% among contacts in the 2-dose and 3-dose groups, respectively. We estimated that the adjusted effectiveness of the inactivated booster vaccine versus 2 doses against Omicron infection was 35.5% (95% CI 2.0, 57.5). The booster dose provided a higher level of protection, with an effectiveness of 60.2% (95% CI 22.8, 79.5) for 15-180 days after vaccination, but this VE decreased to 35.0% (95% CI 2.8, 56.5) after 180 days. Evidence for the protection of the booster dose was detected among young adults aged 18-39 years, but was not detected for those aged 40 years or older.

INTERPRETATION

The receipt of the inactivated vaccine booster dose was associated with a significantly lower Omicron infection risk, and our findings confirmed the vaccine effectiveness (VE) of booster doses against Omicron BA.5 variants. Given the rapid evolution of SARS-CoV-2, we highlight the importance of continuously monitoring the protective performance of vaccines against the genetic variants of SARS-CoV-2, regardless of existing vaccine coverage.

Distinguishing the Vaccine Effectiveness of Inactivated BBIBP-CorV Vaccine Booster Against the Susceptibility, Infectiousness, and Transmission of Omicron Stains: A Retrospective Cohort Study in Urumqi, China

INTRODUCTION

With COVID-19 vaccination rolled out globally, increasing numbers of studies have shown that booster vaccines can enhance an individual's protection against the infection, hospitalization, and death caused by SARS-CoV-2. This study evaluated the effectiveness of COVID-19 vaccine BBIBP-CorV booster against being infected (susceptibility), infecting others (infectiousness), and spreading the disease from one to another (transmission).

METHODS

This retrospective cohort study investigated the close contacts of all officially ascertained COVID-19 confirmed cases in Urumqi, China between August 1 and September 7, 2022. Eligible records were divided into four subcohorts based on the vaccination status of both the close contact and their source case: group 2-2, 2-dose contacts seeded by 2-dose source case (as the reference level); group 2-3, 3-dose contacts seeded by 2-dose source case; group 3-2, 2-dose contacts seeded by 3-dose source case; and group 3-3, 3-dose contacts seeded by 3-dose source case. In the four subcohorts, multivariate logistic regression models were used to examine the vaccine effectiveness (VE) for the BBIBP-CorV booster dose. We adjusted for potential confounding variables, including the sex and age of source cases and close contacts, the calendar week of contact history and contact settings. We evaluated the statistical uncertainty using a 95% confidence interval (CI). In addition, we conducted subgroup analyses to evaluate VE by sex.

RESULTS

The sample sizes of groups 2-2, 2-3, 3-2, and 3-3 were 1184, 3773, 4723, and 27,136 individuals, respectively. Overall VE against susceptibility (group 2-3 vs 2-2) was 42.1% (95% CI 10.6, 62.5), VE against infectiousness (group 3-2 vs 2-2) was 62.0% (95% CI 37.2, 77.0), and VE against transmission (group 3-3 vs 2-2) was 83.7% (95% CI 75.1, 89.4). In the sex-stratified subgroups, male close contacts showed similar VE compared to the overall. However, among female close contacts, while the booster dose improved VE against infectiousness and VE against susceptibility, the VEs were not significantly different from zero.

CONCLUSION

BBIBP-CorV vaccine booster was associated with mild to moderate levels of protection against Omicron susceptibility, infectiousness, and transmission. Real-world assessment of protective performance of COVID-19 vaccines against the risk of Omicron strains is continuously needed, and may provide information that helps vaccination strategy.

Clinical Data based XGBoost Algorithm for infection risk prediction of patients with decompensated cirrhosis: a 10-year (2012-2021) Multicenter Retrospective Case-control study

OBJECTIVES

To appraise effective predictors for infection in patients with decompensated cirrhosis (DC) by using XGBoost algorithm in a retrospective case-control study.

METHODS

Clinical data were retrospectively collected from 6,648 patients with DC admitted to five tertiary hospitals. Indicators with significant differences were determined by univariate analysis and least absolute contraction and selection operator (LASSO) regression. Further multi-tree extreme gradient boosting (XGBoost) machine learning-based model was used to rank importance of features selected from LASSO and subsequently constructed infection risk prediction model with simple-tree XGBoost model. Finally, the simple-tree XGBoost model is compared with the traditional logical regression (LR) model. Performances of models were evaluated by area under the receiver operating characteristic curve (AUROC), sensitivity, and specificity.

RESULTS

Six features, including total bilirubin, blood sodium, albumin, prothrombin activity, white blood cell count, and neutrophils to lymphocytes ratio were selected as predictors for infection in patients with DC. Simple-tree XGBoost model conducted by these features can predict infection risk accurately with an AUROC of 0.971, sensitivity of 0.915, and specificity of 0.900 in training set. The performance of simple-tree XGBoost model is better than that of traditional LR model in training set, internal verification set, and external feature set (P < 0.001).

CONCLUSIONS

The simple-tree XGBoost predictive model developed based on a minimal amount of clinical data available to DC patients with restricted medical resources could help primary healthcare practitioners promptly identify potential infection.

Identification and validation of disulfidptosis-associated molecular clusters in non-alcoholic fatty liver disease

Objective: Non-alcoholic fatty liver disease (NAFLD) is the most prevalent liver disease in the world, and its pathogenesis is not fully understood. Disulfidptosis is the most recently reported form of cell death and may be associated with NAFLD progression. Our study aimed to explore the molecular clusters associated with disulfidptosis in NAFLD and to construct a predictive model. Methods: First, we analyzed the expression profile of the disulfidptosis regulators and immune characteristics in NAFLD. Using 104 NAFLD samples, we investigated molecular clusters based on differentially expressed disulfidptosis-related genes, along with the related immune cell infiltration. Cluster-specific differentially expressed genes were then identified by using the WGCNA method. We also evaluated the performance of four machine learning models before choosing the optimal machine model for diagnosis. Nomogram, calibration curves, decision curve analysis, and external datasets were used to confirm the prediction effectiveness. Finally, the expression levels of the biomarkers were assessed in a mouse model of a high-fat diet. Results: Two differentially expressed DRGs were identified between healthy and NAFLD patients. We revealed the expression profile of DRGs in NAFLD and the correlation with 22 immune cells. In NAFLD, two clusters of molecules connected to disulfidptosis were defined. Significant immunological heterogeneity was shown by immune infiltration analysis among the various clusters. A significant amount of immunological infiltration was seen in Cluster 1. Functional analysis revealed that Cluster 1 differentially expressed genes were strongly linked to energy metabolism and immune control. The highest discriminatory performance was demonstrated by the SVM model, which had a higher area under the curve, relatively small residual and root mean square errors. Nomograms, calibration curves, and decision curve analyses were used to show how accurate the prediction of NAFLD was. Further analysis revealed that the expression of three model-related genes was significantly associated with the level of multiple immune cells. In animal experiments, the expression trends of DDO, FRK and TMEM19 were consistent with the results of bioinformatics analysis. Conclusion: This study systematically elucidated the complex relationship between disulfidptosis and NAFLD and developed a promising predictive model to assess the risk of disease in patients with disulfidptosis subtypes and NAFLD.

Influenza vaccine effectiveness against influenza A during the delayed 2022/23 epidemic in Shihezi, China

After the temporary end of COVID-19 in China in February 2023, the influenza epidemic peaked in March across many Chinese places. We recruited a total of 258 all-age subjects presenting influenza-like illness (ILI) in Shihezi city, China from January 1 to March 16, 2023, and tested for influenza virus infection. Using a test-negative design, we assessed influenza vaccine effectiveness (VE) of 56.3% (95% CrI: 13.6, 73.6) against medically attended, influenza illness during the delayed 2022/23 influenza epidemic. The findings contributed to the continuous monitoring of the influenza vaccine performance across the world, especially in the "post-COVID" pandemic era.

Fluorine-Containing Functional Group-Based Energetic Materials

Molecules featuring fluorine-containing functional groups exhibit outstanding properties with high density, low sensitivity, excellent thermal stability, and good energetic performance due to the strong electron-withdrawing ability and high density of fluorine. Hence, they play a pivotal role in the field of energetic materials. In light of current theoretical and experimental reports, this review systematically focuses on three types of energetic materials possessing fluorine-containing functional groups F- and NF2 - substituted trinitromethyl groups (C(NO2 )2 F, C(NO2 )2 NF2 ), trifluoromethyl group (CF3 ), and difluoroamino and pentafluorosulfone groups (NF2 , SF5 ) and investigates the synthetic methods, physicochemical parameters, and energetic properties of each. The incorporation of fluorine-containing functional moieties is critical for the development of novel high energy density materials, and is rapidly being adopted in the design of energetic materials.

Effectiveness of BNT162b2 and Sinovac vaccines against the transmission of SARS-CoV-2 during Omicron-predominance in Hong Kong: A retrospective cohort study of COVID-19 cases

BACKGROUND

In 2022, SARS-CoV-2 Omicron variants circulated globally, generating concerns about increased transmissibility and immune escape. Hong Kong, having an infection-naive population with a moderate 2-dose vaccine coverage (63% by the end of 2021), experienced a COVID-19 epidemic largely seeded by Omicron BA.2 variants that led to the greatest outbreak in the region to date. Little remains known about the protection of commonly-administered vaccines against transmission of Omicron BA.2 variants.

METHODS

In this retrospective cohort study, we identified 17 535 laboratory-confirmed COVID-19 cases using contact tracing information during the Omicron-predominant period between January and June 2022 in Hong Kong. Demographic characteristics, time from positive test result to case reporting, isolation, or hospital admission, as well as contact tracing history and contact setting were extracted. Transmission pairs were reconstructed through suspected epidemiological links according to contact tracing history, and the number of secondary cases was determined for each index case as a measurement for risk of transmission. The effectiveness of mRNA vaccine (BNT162b2) and inactivated vaccine (Sinovac) against transmission of BA.2 variants was estimated using zero-inflated negative binomial regression models.

RESULTS

Vaccine effectiveness against transmission for patients who received the 2-dose BNT162b2 vaccine was estimated at 56.2% (95% CI: 14.5, 77.6), 30.6% (95% CI: 13.0, 44.6), and 21.3% (95% CI: 2.9, 36.2) on 15 - 90, 91 - 180, and 181 - 270 days after vaccination, respectively, showing a significant decrease over time. For 3-dose vaccines, vaccine effectiveness estimates were 41.0% (95% CI: 11.3, 60.7) and 41.9% (95% CI: 6.1, 64.0) on 15 - 180 days after booster doses of Sinovac and BNT162b2, respectively. Although significant vaccine effectiveness was detected in household settings, no evidence of such protective association was detected in non-household settings for either Sinovac or BNT162b2.

CONCLUSION

Moderate and significant protection against Omicron BA.2 variants' transmission was found for 2 and 3 doses of Sinovac or BNT162b2 vaccines. Although protection by 2-dose BNT162b2 may evidently wane with time, protection could be restored by the booster dose. Here, we highlight the importance of continuously evaluating vaccine effectiveness against transmission for emerging SARS-CoV-2 variants.

Randomized phase II adjuvant trial to compare two treatment durations of icotinib (2 years versus 1 year) for stage II-IIIA EGFR-positive lung adenocarcinoma patients (ICOMPARE study)

BACKGROUND

Despite the prolonged median disease-free survival (DFS) by adjuvant targeted therapy in non-small-cell lung cancer patients with epidermal growth factor receptor (EGFR) mutations, the relationship between the treatment duration and the survival benefits in patients remains unknown.

PATIENTS AND METHODS

In this multicenter, randomized, open-label, phase II trial, eligible patients aged 18-75 years with EGFR-mutant, stage II-IIIA lung adenocarcinoma and who had not received adjuvant chemotherapy after complete tumor resection were enrolled from eight centers in China. Patients were randomly assigned (1 : 1) to receive either 1-year or 2-year icotinib (125 mg thrice daily). The primary endpoint was DFS assessed by investigator. The secondary endpoints were overall survival (OS) and safety. This study was registered at ClinicalTrials.gov (NCT01929200).

RESULTS

Between September 2013 and October 2018, 109 patients were enrolled (1-year group, n = 55; 2-year group, n = 54). Median DFS was 48.9 months [95% confidence interval (CI) 33.1-70.1 months] in the 2-year group and 32.9 months (95% CI 26.6-44.8 months) in the 1-year group [hazard ratio (HR) 0.51; 95% CI 0.28-0.94; P = 0.0290]. Median OS for patients was 75.8 months [95% CI 64.4 months-not evaluable (NE)] in the 2-year group and NE (95% CI 66.3 months-NE) in the 1-year group (HR 0.34; 95% CI 0.13-0.95; P = 0.0317). Treatment-related adverse events (TRAEs) were observed in 41 of 55 (75%) patients in the 1-year group and in 36 of 54 (67%) patients in the 2-year group. Grade 3-4 TRAEs occurred in 4 of 55 (7%) patients in the 1-year group and in 3 of 54 (6%) patients in the 2-year group. No treatment-related deaths or interstitial lung disease was reported.

CONCLUSIONS

Two-year adjuvant icotinib was shown to significantly improve DFS and provide an OS benefit in EGFR-mutant, stage II-IIIA lung adenocarcinoma patients compared with 1-year treatment in this exploratory phase II study.

De novo pyrimidine biosynthetic complexes support cancer cell proliferation and ferroptosis defence

De novo pyrimidine biosynthesis is achieved by cytosolic carbamoyl-phosphate synthetase II, aspartate transcarbamylase and dihydroorotase (CAD) and uridine 5'-monophosphate synthase (UMPS), and mitochondrial dihydroorotate dehydrogenase (DHODH). However, how these enzymes are orchestrated remains enigmatical. Here we show that cytosolic glutamate oxaloacetate transaminase 1 clusters with CAD and UMPS, and this complex then connects with DHODH, which is mediated by the mitochondrial outer membrane protein voltage-dependent anion-selective channel protein 3. Therefore, these proteins form a multi-enzyme complex, named 'pyrimidinosome', involving AMP-activated protein kinase (AMPK) as a regulator. Activated AMPK dissociates from the complex to enhance pyrimidinosome assembly but inactivated UMPS, which promotes DHODH-mediated ferroptosis defence. Meanwhile, cancer cells with lower expression of AMPK are more reliant on pyrimidinosome-mediated UMP biosynthesis and more vulnerable to its inhibition. Our findings reveal the role of pyrimidinosome in regulating pyrimidine flux and ferroptosis, and suggest a pharmaceutical strategy of targeting pyrimidinosome in cancer treatment.

Improved Measurement of the Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay

Reactor neutrino experiments play a crucial role in advancing our knowledge of neutrinos. In this Letter, the evolution of the flux and spectrum as a function of the reactor isotopic content is reported in terms of the inverse-beta-decay yield at Daya Bay with 1958 days of data and improved systematic uncertainties. These measurements are compared with two signature model predictions: the Huber-Mueller model based on the conversion method and the SM2018 model based on the summation method. The measured average flux and spectrum, as well as the flux evolution with the ^{239}Pu isotopic fraction, are inconsistent with the predictions of the Huber-Mueller model. In contrast, the SM2018 model is shown to agree with the average flux and its evolution but fails to describe the energy spectrum. Altering the predicted inverse-beta-decay spectrum from ^{239}Pu fission does not improve the agreement with the measurement for either model. The models can be brought into better agreement with the measurements if either the predicted spectrum due to ^{235}U fission is changed or the predicted ^{235}U, ^{238}U, ^{239}Pu, and ^{241}Pu spectra are changed in equal measure.

Frailty as a risk marker of adverse lower urinary symptom outcomes in patients with benign prostatic hyperplasia undergoing transurethral resection of prostate

Purpose

Lower urinary symptoms (LUTS) may persist in a proportion of patients with benign prostatic hyperplasia (BPH) following transurethral resection of prostate (TURP), which is a major cause of reduced quality-of-life. We aimed to investigate the effect of frailty on LUTS in patients with BPH treated with TURP.

Methods

We longitudinally evaluated LUTS and health-related quality-of-life (HRQOL) in patients with BPH treated with TURP from February 2019 and January 2022 using International Prostate Symptom Score (IPSS) and Short Form-8 (SF-8), respectively. Patients were divided into frail and non-frail groups according to the Fried phenotype (FP). The primary purpose was comparing the outcomes of LUTS and HRQOL between two groups. Secondary purposes were investigating the frailty as a preoperative predictor of postoperative adverse LUTS outcomes following TURP using logistic regression analysis. A 1:2 propensity score matching (PSM) was performed to reduce the effects of selection bias and potential confounders.

Results

Of the 567 patients enrolled, 495 (87.3%) patients were non-frail (FP = 0-2), and the remaining 72 (12.7%) patients were classified into the frail group. There were no significant differences in body mass index (BMI), urine white blood cell (UWBC), creatinine, prostate-specific antigen (PSA) and prostate volume in both groups at baseline (all p > 0.05). However, patients with frailty were older, higher comorbidity rates, lower peak flow rates and lower HRQOL. In the frail group, although LUTS and HRQOL at 6 months following TURP improved significantly compared to those at baseline, it did not show a significant improvement compared with the non-frail group (both p < 0.001). Moreover, multivariable logistic regression analysis demonstrated that preoperative frailty was significantly associated with poor LUTS improvement in both the entire cohort and PSM subset (both p < 0.05), whereas age and comorbidities were not after PSM analysis.

Conclusion

In patients with frail or non-frail, TURP for BPH provides overall good results. However, frail individuals are at higher risk of postoperative adverse LUTS outcomes. Frailty has the potential to be a strong objective tool for risk stratification and should be considered during the perioperative evaluation.

Case clustering, contact stratification, and transmission heterogeneity of SARS-CoV-2 Omicron BA.5 variants in Urumqi, China: An observational study

Background

From August to September 2022, Urumqi, the capital of the Xinjiang Uygur Autonomous Region in China, faced its largest COVID-19 outbreak caused by the emergence of the SARS-CoV-2 Omicron BA.5.2 variants. Although the superspreading of COVID-19 played an important role in triggering large-scale outbreaks, little was known about the superspreading potential and heterogeneity in the transmission of Omicron BA.5 variants.

Methods

In this retrospective observational, contact tracing study, we identified 1139 laboratory-confirmed COVID-19 cases of Omicron BA.5.2 variants, and 51 323 test-negative close contacts in Urumqi from 7 August to 7 September 2022. By using detailed contact tracing information and exposure history of linked case-contact pairs, we described stratification in contact and heterogeneity in transmission across different demographic strata, vaccine statuses, and contact settings. We adopted beta-binomial models to characterise the secondary attack rate (SAR) distribution among close contacts and modelled COVID-19 transmission as a branching process with heterogeneity in transmission governed by negative binomial models.

Results

After the city lockdown, the mean case cluster size decreased from 2.0 (before lockdown) to 1.6, with decreased proportions of contacts in workplace and community settings compared with household settings. We estimated that 14% of the most infectious index cases generated 80% transmission, whereas transmission in the community setting presented the highest heterogeneity, with 5% index cases seeding 80% transmission. Compared with zero, one, and two doses of inactivated vaccine (Sinopharm), index cases with three doses of vaccine had a lower risk of generating secondary cases in terms of the reproduction number. Contacts of female cases, cases with ages 0-17 years, and household settings had relatively higher SAR.

Conclusions

In the context of intensive control measures, active case detection, and relatively high vaccine coverage, but with an infection-naive population, our findings suggested high heterogeneity in the contact and transmission risks of Omicron BA.5 variants across different demographic strata, vaccine statuses, and contact settings. Given the rapid evolution of SARS-CoV-2, investigating the distribution of transmission not only helped promote public awareness and preparedness among high-risk groups, but also highlighted the importance of continuously monitoring the transmission characteristics of genetic variants of SARS-CoV-2.

Changes in all-cause and cause-specific excess mortality before and after the Omicron outbreak of COVID-19 in Hong Kong

Background

While coronavirus 2019 (COVID-19) deaths were generally underestimated in many countries, Hong Kong may show a different trend of excess mortality due to stringent measures, especially for deaths related to respiratory diseases. Nevertheless, the Omicron outbreak in Hong Kong evolved into a territory-wide transmission, similar to other settings such as Singapore, South Korea, and recently, mainland China. We hypothesized that the excess mortality would differ substantially before and after the Omicron outbreak.

Methods

We conducted a time-series analysis of daily deaths stratified by age, reported causes, and epidemic wave. We determined the excess mortality from the difference between observed and expected mortality from 23 January 2020 to 1 June 2022 by fitting mortality data from 2013 to 2019.

Results

During the early phase of the pandemic, the estimated excess mortality was -19.92 (95% confidence interval (CI) = -29.09, -10.75) and -115.57 (95% CI = -161.34, -69.79) per 100 000 population overall and for the elderly, respectively. However, the overall excess mortality rate was 234.08 (95% CI = 224.66, 243.50) per 100 000 population overall and as high as 928.09 (95% CI = 885.14, 971.04) per 100 000 population for the elderly during the Omicron epidemic. We generally observed negative excess mortality rates of non-COVID-19 respiratory diseases before and after the Omicron outbreak. In contrast, increases in excess mortality were generally reported in non-respiratory diseases after the Omicron outbreak.

Conclusions

Our results highlighted the averted mortality before 2022 among the elderly and patients with non-COVID-19 respiratory diseases, due to indirect benefits from stringent non-pharmaceutical interventions. The high excess mortality during the Omicron epidemic demonstrated a significant impact from the surge of COVID-19 infections in a SARS-CoV-2 infection-naive population, particularly evident in the elderly group.

Precision Measurement of Reactor Antineutrino Oscillation at Kilometer-Scale Baselines by Daya Bay

We present a new determination of the smallest neutrino mixing angle θ_{13} and the mass-squared difference Δm_{32}^{2} using a final sample of 5.55×10^{6} inverse beta-decay (IBD) candidates with the final-state neutron captured on gadolinium. This sample is selected from the complete dataset obtained by the Daya Bay reactor neutrino experiment in 3158 days of operation. Compared to the previous Daya Bay results, selection of IBD candidates has been optimized, energy calibration refined, and treatment of backgrounds further improved. The resulting oscillation parameters are sin^{2}2θ_{13}=0.0851±0.0024, Δm_{32}^{2}=(2.466±0.060)×10^{-3}  eV^{2} for the normal mass ordering or Δm_{32}^{2}=-(2.571±0.060)×10^{-3}  eV^{2} for the inverted mass ordering.

High-Performance Artificial Synapse Based on CVD-Grown WSe2 Flakes with Intrinsic Defects

High-performance artificial synaptic devices with rich functions are highly desired for the development of an advanced brain-like neuromorphic system. Here, we prepare synaptic devices based on a CVD-grown WSe₂ flake, which has an unusual morphology of nested triangles. The WSe₂ transistor exhibits robust synaptic behaviors such as excitatory postsynaptic current, paired-pulse facilitation, short-time plasticity, and long-time plasticity. Furthermore, due to its high sensitivity to light illumination, the WSe₂ transistor exhibits excellent light-dosage-dependent and light wavelength-dependent plasticity, which endow the synaptic device with more intelligent learning and memory functions. In addition, WSe₂ optoelectronic synapses can mimic "learning experience" behavior and associative learning behavior like the brain. An artificial neural network is simulated for pattern recognition of hand-written digital images in the MNIST data set and the best recognition accuracy could reach 92.9% based on weight updating training of our WSe₂ device. Detailed surface potential analysis and PL characterization reveal that the intrinsic defects generated in growth are dominantly responsible for the controllable synaptic plasticity. Our work suggests that the CVD-grown WSe₂ flake with intrinsic defects capable of robust trapping/de-trapping charges holds great application prospects in future high-performance neuromorphic computation.

[Chinese expert consensus on perioperative management of renal tumor cryoablation (2022 edition)]

In recent years, the incidence of renal cancer has been increasing continuously. Surgical resection is the "gold standard" for the treatment of small renal cancer. However, local ablation therapy of renal cancer is undoubtedly the best choice for patients with short life expectancy, other complications, and impaired renal function who are not suitable for surgery. In recent years, with the development of ablation techniques and long-term follow-up, local ablation has shown good therapeutic effects. As many domestic hospitals are performing or planning to perform renal tumor cryoablation to improve the clinical cure rate and surgical safety of renal tumor cryoablation, it is necessary to standardize the surgical indications, contraindications, perioperative management, efficacy evaluation, and other common problems. Currently, there is no expert consensus regarding perioperative renal tumor cryoablation in China. To standardize the perioperative management of renal tumor cryoablation and related technical operations in clinical practice, and improve the effectiveness and safety of cryoablation, the expert committee of Tumor Interventional and Minimally Invasive Diagnosis and Treatment Continuing Education Base of the Chinese Anti-Cancer Association convened experts in related fields to discuss and formulate this consensus, which is hereby published, for clinical reference and application.

Bacterial antibiotic resistance among cancer inpatients in China: 2016-20

BACKGROUND

The incidence of infections among cancer patients is as high as 23.2-33.2% in China. However, the lack of information and data on the number of antibiotics used by cancer patients is an obstacle to implementing antibiotic management plans.

AIM

This study aimed to investigate bacterial infections and antibiotic resistance in Chinese cancer patients to provide a reference for the rational use of antibiotics.

DESIGN

This was a 5-year retrospective study on the antibiotic resistance of cancer patients.

METHODS

In this 5-year surveillance study, we collected bacterial and antibiotic resistance data from 20 provincial cancer diagnosis and treatment centers and three specialized cancer hospitals in China. We analyzed the resistance of common bacteria to antibiotics, compared to common clinical drug-resistant bacteria, evaluated the evolution of critical drug-resistant bacteria and conducted data analysis.

FINDINGS

Between 2016 and 2020, 216 219 bacterial strains were clinically isolated. The resistance trend of Escherichia coli and Klebsiella pneumoniae to amikacin, ciprofloxacin, cefotaxime, piperacillin/tazobactam and imipenem was relatively stable and did not significantly increase over time. The resistance of Pseudomonas aeruginosa strains to all antibiotics tested, including imipenem and meropenem, decreased over time. In contrast, the resistance of Acinetobacter baumannii strains to carbapenems increased from 4.7% to 14.7%. Methicillin-resistant Staphylococcus aureus (MRSA) significantly decreased from 65.2% in 2016 to 48.9% in 2020.

CONCLUSIONS

The bacterial prevalence and antibiotic resistance rates of E. coli, K. pneumoniae, P. aeruginosa, A. baumannii, S. aureus and MRSA were significantly lower than the national average.

[Selection of classic laryngeal mask airway size based on ideal body mass in patients with low body mass index: a randomized trial]

OBJECTIVE

To compare the effect of laryngeal mask airway (LMA) size selection based on ideal and actual body mass on the success rate of first insertion in patients with low body mass index (BMI).

METHODS

This study was performed in 137 patients aged 18-60 years with BMI below 18.5 kg/m², in whom discrepancies occurred in the selection of LMA size based on their actual body mass and the ideal body mass. The patients were randomized divided into ideal body mass group and actual body mass group, in which the size of LMA was selected based on the ideal body mass and their actual body mass, respectively. The success rate of first LMA insertion, overall success rate, fiberoptic visual field grade, leakage pressure, and LMA-related complications of the patients were recorded during the maintenance and recovery of anesthesia.

RESULTS

The success rate of first LMA insertion was significantly higher in ideal body mass group than in the actual body mass group (86.8% vs 68.1%, P=0.016). Compared with those in the actual body mass group, the patients in the ideal body mass group used larger LMA (P < 0.005) and had better fiberoptic field scores (P=0.001) and higher airway seal pressure (P < 0.005). The peak inspiratory pressure (P=0.154) or the incidence of LMA-related complications during anesthesia maintenance and recovery did not differ significantly between the two groups (P>0.05).

CONCLUSION

The size selection of LMA based on the ideal body mass of the patients, determined according to their height and sex, can significantly improve the success rate of first LMA insertion in patients with low BMI.

Comparing the incubation period, serial interval, and infectiousness profile between SARS-CoV-2 Omicron and Delta variants

BACKGROUND

In January 2022, the SARS-CoV-2 Omicron variant initiated major outbreaks and dominated the transmissions in Hong Kong, displacing an earlier outbreak seeded by the Delta variants. To provide insight into the transmission potential of the emerging variants, we aimed to compare the epidemiological characteristics of the Omicron and Delta variants.

METHODS

We analysed the line-list clinical and contact tracing data of the SARS-CoV-2 confirmed cases in Hong Kong. Transmission pairs were constructed based on the individual contact history. We fitted bias-controlled models to the data to estimate the serial interval, incubation period and infectiousness profile of the two variants. Viral load data were extracted and fitted to the random effect models to investigate the potential risk modifiers for the clinical viral shedding course.

RESULTS

Totally 14401 confirmed cases were reported between January 1 and February 15, 2022. The estimated mean serial interval (4.4 days vs 5.8 days) and incubation period (3.4 days vs 3.8 days) were shorter for the Omicron than the Delta variants. A larger proportion of pre-symptomatic transmission was observed for the Omicron (62%) compared to the Delta variants (48%). The Omicron cases had higher mean viral load over an infection course than the Delta cases, with the elder cases appearing more infectious than the younger cases for both variants.

CONCLUSION

The epidemiological features of Omicron variant were likely an obstacle to contact tracing measures, imposed as a major intervention in settings like Hong Kong. Continuously monitoring the epidemiological feature for any emerging SARS-CoV-2 variants in the future is needed to assist officials in planning measures for COVID-19 control. This article is protected by copyright. All rights reserved.

Template-Assisted Synthesis of a Large-Area Ordered Perovskite Nanowire Array for a High-Performance Photodetector

One-dimensional (1D) organic-inorganic hybrid perovskite nanowires (NWs) with well-defined structures possess superior optical and electrical properties for optoelectronic applications. However, most of the perovskite NWs are synthesized in air, which makes the NWs susceptible to water vapor, resulting in large amounts of grain boundaries or surface defects. Here, a template-assisted antisolvent crystallization (TAAC) method is designed to fabricate CH₃NH₃PbBr₃ NWs and arrays. It is found that the as-synthesized NW array has designable shapes, low crystal defects, and ordered alignment, which is attributed to the sequestration of water and oxygen in air by the introduction of acetonitrile vapor. The photodetector based on the NWs exhibits an excellent response to light illumination. Under the illumination of a 532 nm laser with 0.1 μW and a bias of -1 V, the responsivity and detectivity of the device reach 1.55 A/W and 1.21 × 10¹² Jones, respectively. The transient absorption spectrum (TAS) shows a distinct ground state bleaching signal only at 527 nm, which corresponds to the absorption peak induced by the interband transition of CH₃NH₃PbBr₃. Narrow absorption peaks (a few nanometers) indicate that the energy-level structures of CH₃NH₃PbBr₃ NWs only have a few impurity-level-induced transitions leading to additional optical loss. This work provides an effective and simple strategy to achieve high-quality CH₃NH₃PbBr₃ NWs, which exhibit potential application in photodetection.

Dining-Out Behavior as a Proxy for the Superspreading Potential of SARS-CoV-2 Infections: Modeling Analysis

BACKGROUND

While many studies evaluated the reliability of digital mobility metrics as a proxy of SARS-CoV-2 transmission potential, none examined the relationship between dining-out behavior and the superspreading potential of COVID-19.

OBJECTIVE

We employed the mobility proxy of dining out in eateries to examine this association in Hong Kong with COVID-19 outbreaks highly characterized by superspreading events.

METHODS

We retrieved the illness onset date and contact-tracing history of all laboratory-confirmed cases of COVID-19 from February 16, 2020, to April 30, 2021. We estimated the time-varying reproduction number (Rt) and dispersion parameter (k), a measure of superspreading potential, and related them to the mobility proxy of dining out in eateries. We compared the relative contribution to the superspreading potential with other common proxies derived by Google LLC and Apple Inc.

RESULTS

A total of 6391 clusters involving 8375 cases were used in the estimation. A high correlation between dining-out mobility and superspreading potential was observed. Compared to other mobility proxies derived by Google and Apple, the mobility of dining-out behavior explained the highest variability of k (ΔR-sq=9.7%, 95% credible interval: 5.7% to 13.2%) and Rt (ΔR-sq=15.7%, 95% credible interval: 13.6% to 17.7%).

CONCLUSIONS

We demonstrated that there was a strong link between dining-out behaviors and the superspreading potential of COVID-19. The methodological innovation suggests a further development using digital mobility proxies of dining-out patterns to generate early warnings of superspreading events.

Superspreading potentials of SARS-CoV-2 Delta variants across different contact settings in Eastern China: A retrospective observational study

OBJECTIVES

As the genetic variants of SARS-CoV-2 continuously pose threats to global health, evaluating superspreading potentials of emerging genetic variants is of importance for region-wide control of COVID-19 outbreaks.

METHODS

By using detailed epidemiological contact tracing data of test-positive COVID-19 cases collected between July and August 2021 in Nanjing and Yangzhou, China, we assessed the superspreading potential of outbreaks seeded by SARS-CoV-2 Delta variants. The transmission chains and case-clusters were constructed according to the individual-based surveillance data. We modelled the disease transmission as a classic branching process with transmission heterogeneity governed by negative binomial models. Subgroup analysis was conducted by different contact settings and age groups.

RESULTS

We reported a considerable heterogeneity in the contact patterns and transmissibility of Delta variants in eastern China. We estimated an expected 14% (95% CI: 11-16%) of the most infectious cases generated 80% of the total transmission.

CONCLUSIONS

Delta variants demonstrated a significant potential of superspreading under strict control measures and active COVID-19 detecting efforts. Enhancing the surveillance on disease transmissibility especially in high-risk settings, along with rapid contact tracing and case isolations would be one of the key factors to mitigate the epidemic caused by the emerging genetic variants of SARS-CoV-2.

A statistical framework for tracking the time-varying superspreading potential of COVID-19 epidemic

Timely detection of an evolving event of an infectious disease with superspreading potential is imperative for territory-wide disease control as well as preventing future outbreaks. While the reproduction number (R) is a commonly-adopted metric for disease transmissibility, the transmission heterogeneity quantified by dispersion parameter k, a metric for superspreading potential is seldom tracked. In this study, we developed an estimation framework to track the time-varying risk of superspreading events (SSEs) and demonstrated the method using the three epidemic waves of COVID-19 in Hong Kong. Epidemiological contact tracing data of the confirmed COVID-19 cases from 23 January 2020 to 30 September 2021 were obtained. By applying branching process models, we jointly estimated the time-varying R and k. Individual-based outbreak simulations were conducted to compare the time-varying assessment of the superspreading potential with the typical non-time-varying estimate of k over a period of time. We found that the COVID-19 transmission in Hong Kong exhibited substantial superspreading during the initial phase of the epidemics, with only 1 % (95 % Credible interval [CrI]: 0.6-2 %), 5 % (95 % CrI: 3-7 %) and 10 % (95 % CrI: 8-14 %) of the most infectious cases generated 80 % of all transmission for the first, second and third epidemic waves, respectively. After implementing local public health interventions, R estimates dropped gradually and k estimates increased thereby reducing the risk of SSEs to approaching zero. Outbreak simulations indicated that the non-time-varying estimate of k may overlook the possibility of large outbreaks. Hence, an estimation of the time-varying k as a compliment of R as a monitoring of both disease transmissibility and superspreading potential, particularly when public health interventions were relaxed is crucial for minimizing the risk of future outbreaks.

Transmission Characteristics and Inactivated Vaccine Effectiveness Against Transmission of SARS-CoV-2 Omicron BA.5 Variants in Urumqi, China

Importance

In 2022, Omicron variants circulated globally, and Urumqi, China, experienced a COVID-19 outbreak seeded by Omicron BA.5 variants, resulting in the highest number of infections in the city's record before the exit of the zero COVID-19 strategy. Little was known about the characteristics of Omicron variants in mainland China.

Objective

To evaluate transmission characteristics of Omicron BA.5 variants and the effectiveness of inactivated vaccine (mainly BBIBP-CorV) against their transmission.

Design, Setting, and Participants

This cohort study was conducted using data from an Omicron-seeded COVID-19 outbreak in Urumqi from August 7 to September 7, 2022. Participants included all individuals with confirmed SARS-CoV-2 infections and their close contacts identified between August 7 and September 7, 2022 in Urumqi.

Exposures

A booster dose was compared vs 2 doses (reference level) of inactivated vaccine and risk factors were evaluated.

Main Outcomes and Measures

Demographic characteristics, timeline records from exposure to laboratory testing outcomes, contact tracing history, and contact setting were obtained. The mean and variance of the key time-to-event intervals of transmission were estimated for individuals with known information. Transmission risks and contact patterns were assessed under different disease-control measures and in different contact settings. The effectiveness of inactivated vaccine against the transmission of Omicron BA.5 was estimated using multivariate logistic regression models.

Results

Among 1139 individuals diagnosed with COVID-19 (630 females [55.3%]; mean [SD] age, 37.4 [19.9] years) and 51 323 close contacts who tested negative for COVID-19 (26 299 females [51.2%]; mean [SD] age, 38.4 [16.0] years), the means of generation interval, viral shedding period, and incubation period were estimated at 2.8 days (95% credible interval [CrI], 2.4-3.5 days), 6.7 days (95% CrI, 6.4-7.1 days), and 5.7 days (95% CrI, 4.8-6.6 days), respectively. Despite contact tracing, intensive control measures, and high vaccine coverage (980 individuals with infections [86.0%] received ≥2 doses of vaccine), high transmission risks were found in household settings (secondary attack rate, 14.7%; 95% CrI, 13.0%-16.5%) and younger (aged 0-15 years; secondary attack rate, 2.5%; 95% CrI, 1.9%-3.1%) and older age (aged >65 years; secondary attack rate, 2.2%; 95% CrI, 1.5%-3.0%) groups. Vaccine effectiveness against BA.5 variant transmission for the booster-dose vs 2 doses was 28.9% (95% CrI, 7.7%-45.2%) and 48.5% (95% CrI, 23.9%-61.4%) for 15-90 days after booster dose. No protective outcome was detected beyond 90 days after the booster dose.

Conclusions and Relevance

This cohort study revealed key transmission characteristics of SARS-CoV-2 as they evolved, as well as vaccine effectiveness against variants. These findings suggest the importance of continuously evaluating vaccine effectiveness against emerging SARS-CoV-2 variants.