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.

Transition Metal-Free Hydrogenolysis of Anilines to Arenes Mediated by Lithium Hydride.

Hydrodenitrogenation (HDN) of nitrogen-containing organic compounds such as aniline and its derivatives is of scientific interest and practical importance. Major efforts have been devoted to the development and understanding of transition metal-mediated chemical processes. Herein, we report a fundamentally different strategy using a transition metal-free material, that is, lithium hydride (LiH) enabling the hydrogenolysis of aniline to benzene and ammonia via a chemical looping approach. Aniline reacts with LiH to form lithium anilide, and subsequently, the hydrogenolysis of lithium anilide yields benzene and ammonia and regenerates LiH to complete the loop. This LiH-mediated chemical looping HDN process stands in sharp contrast to the transition metal-catalyzed or -mediated processes, which commonly lead to the complete hydrogenation of aromatic rings. A highly denitrogenated product formation rate of 2623 µmol·g-1·h-1 is achieved for the hydrogenolysis of lithium anilide at 300 °C and 10 bar H2, which exceeds the catalytic rate of transition metal catalysts. Computational studies reveal that the scission of C-N bonds is facilitated by a Li-mediated nucleophilic attack of hydride to the α-sp2C atom of aniline. This work not only provides a distinctive chemical looping route for HDN, but also opens up materials space for the denitrogenation of anilines.

Modelling the effects of the contaminated environments on tuberculosis in Jiangsu, China.

Tuberculosis (TB) is still an important public health issue in Jiangsu province, China. In this study, based on the TB transmission routes and the statistical data of TB cases, we formulate a novel TB epidemic model accounting for the effects of the contaminated environments on TB transmission dynamics. The value of this study lies in two aspects. Mathematically, we define the basic reproduction number, R0, and prove that R0 can be used to govern the threshold dynamics of the model. Epidemiologically, we find that the annual average R0 is 1.13,>1 and TB in Jiangsu is an endemic disease. Therefore, in order to control the TB in Jiangsu efficiently, we must decrease the virus shedding rate or increase the recovery rates, and increase the environmental clearance rate.

Shrinkage in serial intervals across transmission generations of COVID-19.

One of the key epidemiological characteristics that shape the transmission of coronavirus disease 2019 (COVID-19) is the serial interval (SI). Although SI is commonly considered following a probability distribution at a population scale, recent studies reported a slight shrinkage (or contraction) of the mean of effective SI across transmission generations or over time. Here, we develop a likelihood-based statistical inference framework with truncation to explore the change in SI across transmission generations after adjusting the impacts of case isolation. The COVID-19 contact tracing surveillance data in Hong Kong are used for exemplification. We find that for COVID-19, the mean of individual SI is likely to shrink with a factor at 0.72 per generation (95%CI: 0.54, 0.96) as the transmission generation increases, where a threshold may exist as the lower boundary of this shrinking process. We speculate that one of the probable explanations for the shrinkage in SI might be an outcome due to the competition among multiple candidate infectors within the same case cluster. Thus, the nonpharmaceutical interventive strategies are crucially important to block the transmission chains, and mitigate the COVID-19 epidemic.

The effect of the fear factor on the dynamics of a predator-prey model incorporating the prey refuge.

In this paper, we investigate the dynamics of an improved Leslie-Gower predator-prey model which is characterized by the reduction of the prey growth rate due to fear of the predator (i.e., antipredator behavior). The value of this study lies in two aspects: mathematically, (i) it provides the existence and the stability of the positive equilibrium; (ii) it gives the existence of the Hopf bifurcation and limit cycle; and (iii) it shows the mechanisms of the fear factor and the prey refuge on the level of the positive equilibrium. Biologically, we find that the influence of the fear factor is complex: (i) increasing the level of fear can cause the level of the population density to decrease and the prey to become extinct; (ii) the effect of the cost of fear on the stability of the positive equilibrium is rich and complex: it can either destabilize the stability and benefit the emergency of the periodic behavior or stabilize the system by excluding the existence of periodic solutions; (iii) with a fixed level of fear, the prey refuge is beneficial to the coexistence of the prey and the predator, and with the increase of the level of the prey refuge, the positive equilibrium may change from stable spiral sink to unstable spiral source to stable spiral sink. These results may enrich the dynamics of the predator-prey systems.

Stochastic persistence and stationary distribution in an SIS epidemic model with media coverage.

This paper aims to study an SIS epidemic model with media coverage from a general deterministic model to a stochastic differential equation with environment fluctuation. Mathematically, we use the Markov semigroup theory to prove that the basic reproduction number R 0 s can be used to control the dynamics of stochastic system. Epidemiologically, we show that environment fluctuation can inhibit the occurrence of the disease, namely, in the case of disease persistence for the deterministic model, the disease still dies out with probability one for the stochastic model. So to a great extent the stochastic perturbation under media coverage affects the outbreak of the disease.

Identifying hotspots and management of critical ecosystem services in rapidly urbanizing Yangtze River Delta Region, China.

Rapid urbanization has altered many ecosystems, causing a decline in many ecosystem services, generating serious ecological crisis. To cope with these challenges, we presented a comprehensive framework comprising five core steps for identifying and managing hotspots of critical ecosystem services in a rapid urbanizing region. This framework was applied in the case study of the Yangtze River Delta (YRD) Region. The study showed that there was large spatial heterogeneity in the hotspots of ecosystem services in the region, hotspots of supporting services and regulating services aggregately distributing in the southwest mountainous areas while hotspots of provisioning services mainly in the northeast plain, and hotspots of cultural services widespread in the waterbodies and southwest mountainous areas. The regionalization of the critical ecosystem services was made through the hotspot analysis. This study provided valuable information for environmental planning and management in a rapid urbanizing region and helped improve China's ecological redlines policy at regional scale.

Behavior of Lithium Amide Under Argon Plasma.

Alkali and alkaline earth metal amides are a type of functional materials for hydrogen storage, thermal energy storage, ion conduction, and chemical transformations such as ammonia synthesis and decomposition. The thermal chemistry of lithium amide (LiNH2), as a simple but representative alkali or alkaline earth metal amide, has been well studied previously encouraged by its potentials in hydrogen storage. In comparison, little is known about the interaction of plasma and LiNH2. Herein, we report that the plasma treatment of LiNH2 in an Ar flow under ambient temperature and pressure gives rise to distinctly different reaction products and reaction pathway from that of the thermal process. We found that plasma treatment of LiNH2 leads to the formation of Li colloids, N2, and H2 as observed by UV-vis absorption, EPR, and gas products analysis. Inspired by this very unique interaction between plasma and LiNH2, a chemical loop for ammonia decomposition to N2 and H2 mediated by LiNH2 was proposed and demonstrated.

Light-driven ammonia synthesis under mild conditions using lithium hydride.

Photon-driven chemical processes are usually mediated by oxides, nitrides and sulfides whose photo-conversion efficiency is limited by charge carrier recombination. Here we show that lithium hydride undergoes photolysis upon ultraviolet illumination to yield long-lived photon-generated electrons residing in hydrogen vacancies, known as F centres. We demonstrate that photon-driven dehydrogenation and dark rehydrogenation over lithium hydride can be fulfilled reversibly at room temperature, which is about 600 K lower than the corresponding thermal process. As light-driven F centre generation could provide an alternative approach to charge carrier separation to favour chemical transformations that are kinetically or thermodynamically challenging, we show that light-activated lithium hydride cleaves the N≡N triple bond to form a N-H bond under mild conditions. Co-feeding a N2/H2 mixture with low H2 partial pressure leads to photocatalytic ammonia formation at near ambient conditions. This work provides insights into the development of advanced materials and processes for light harvesting and conversion.

The influence of ambient air pollution on the transmission of tuberculosis in Jiangsu, China.

In this paper, based on the statistical data, we investigate the effects of long-term exposure to ambient particulate air pollution on the transmission dynamics of tuberculosis (TB) in Jiangsu, China by studying the threshold dynamics of the TB epidemic model via the statistical data analytically and numerically. The basic reproduction number R 0 > 1 reveals that TB in Jiangsu, China is an endemic disease and will persist for a long time. And the numerical results show that, in order to control the TB in Jiangsu effectively, we must decrease the depuration coefficient of PM10 in the body, the proportion of TB symptomatic infectious by direct transmission, the reactivation rate of the pre-symptomatic infectious and the effect coefficient of PM10 and MTB inhaled of TB transmission, and increase the uptake coefficient, the recovery rate of the symptomatic/pre-symptomatic infectious and the influence coefficient of PM10 on the body of mortality. Our study shows that PM10 is closely related to the incidence of TB, and the effective control efforts are suggested to focus on increasing close-contact distance and wearing protective mask to decrease the influence of PM10 on the TB transmission, which may shed a new light on understanding the environmental drivers to TB.

The impact of ambient air pollution on an influenza model with partial immunity and vaccination.

In this paper, we investigate the effects of ambient air pollution (AAP) on the spread of influenza in an AAP-dependent dynamic influenza model. The value of this study lies in two aspects. Mathematically, we establish the threshold dynamics in the term of the basic reproduction number $ \mathcal{R}_0 $: If $ \mathcal{R}_0 < 1 $, the disease will go to extinction, while if $ \mathcal{R}_0 > 1 $, the disease will persist. Epidemiologically, based on the statistical data in Huaian, China, we find that, in order to control the prevalence of influenza, we must increase the vaccination rate, the recovery rate and the depletion rate, and decrease the rate of the vaccine wearing off, the uptake coefficient, the effect coefficient of AAP on transmission rate and the baseline rate. To put it simply, we must change our traveling plan and stay at home to reduce the contact rate or increase the close-contact distance and wear protective masks to reduce the influence of the AAP on the influenza transmission.

Altered Functional Connectivity in Working Memory Network After Acute Sleep Deprivation.

Acute sleep deprivation (SD) has a detrimental effect on working memory (WM). However, prior functional magnetic resonance imaging (fMRI) studies have failed to reach consistent results on brain functions underlying WM decline after acute SD. Thus, we aimed to identify convergent patterns of abnormal brain functions due to WM decline after acute SD. A coordinate-based activation likelihood estimation (ALE) meta-analysis of task-state fMRI studies testing the effects of acute SD on WM was performed to construct WM network. Then 26 healthy subjects with regular sleep performed the n-back task and underwent resting-state fMRI scanning before and after 24 h of SD. The functional connectivity (FC) among these brain regions and correlations with WM performance were calculated. The ALE results displayed that SD subjects performing WM-related tasks had consistent hypoactivation in the occipital lobe, left middle occipital gyrus, parietal lobe, precuneus, inferior parietal lobule, right sub-gyral, right cuneus, right limbic lobe, and right posterior cingulate. Consistent hyperactivation was showed in the left cerebrum, including the lingual gyrus, posterior lobe, cuneus, temporal lobe, and fusiform gyrus. These identified brain regions as the seeds to construct WM network. The increased FC between the left declive and right sub-gyral, left cuneus and left lingual gyrus, and left cuneus and right post cingulate were found. Furthermore, the impaired WM performance negatively correlated with increased FC. Taken together, our findings highlight that the altered FC in WM network may be the underlying mechanisms of WM decline after acute SD.

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.

Dynamics of a stochastic HBV infection model with drug therapy and immune response.

Hepatitis B is a disease that damages the liver, and its control has become a public health problem that needs to be solved urgently. In this paper, we investigate analytically and numerically the dynamics of a new stochastic HBV infection model with antiviral therapies and immune response represented by CTL cells. Through using the theory of stochastic differential equations, constructing appropriate Lyapunov functions and applying Itô's formula, we prove that the disease-free equilibrium of the stochastic HBV model is stochastically asymptotically stable in the large, which reveals that the HBV infection will be eradicated with probability one. Moreover, the asymptotic behavior of globally positive solution of the stochastic model near the endemic equilibrium of the corresponding deterministic HBV model is studied. By using the Milstein's method, we provide the numerical simulations to support the analysis results, which shows that sufficiently small noise will not change the dynamic behavior, while large noise can induce the disappearance of the infection. In addition, the effect of inhibiting virus production is more significant than that of blocking new infection to some extent, and the combination of two treatment methods may be the better way to reduce HBV infection and the concentration of free virus.

Estimating Carbon Sequestration Potential of Forest and Its Influencing Factors at Fine Spatial-Scales: A Case Study of Lushan City in Southern China.

Accurate prediction of forest carbon sequestration potential requires a comprehensive understanding of tree growth relationships. However, the studies for estimating carbon sequestration potential concerning tree growth relationships at fine spatial-scales have been limited. In this paper, we assessed the current carbon stock and predicted sequestration potential of Lushan City, where a region has rich vegetation types in southern China, by introducing parameters of diameter at breast height (DBH) and tree height in the method of coupling biomass expansion factor (BEF) and tree growth equation. The partial least squares regression (PLSR) was used to explore the role of combined condition factors (e.g., site, stand, climate) on carbon sequestration potential. The results showed that (1) in 2019, the total carbon stock of trees in Lushan City was 9.22 × 105 t, and the overall spatial distribution exhibited a decreasing tendency from northwest to south-central, and the carbon density increased with elevation; (2) By 2070, the carbon density of forest in Lushan City will reach a relatively stable state, and the carbon stock will continue to rise to 2.15 × 106 t, which is 2.33 times of the current level, indicating that Lushan forest will continue to serve as a carbon sink for the next fifty years; (3) Excluding the effect of tree growth, regional forest carbon sequestration potential was significantly influenced on site characteristics, which achieved the highest Variable Importance in Projection (VIP) value (2.19) for slope direction. Our study provided a better understanding of the relationships between forest growth and carbon sequestration potential at fine spatial-scales. The results regarding the condition factors and how their combination characteristics affect the potential for carbon sequestration could provide crucial insights for Chinese carbon policy and global carbon neutrality goals.

Unveiling the visible-light-driven photodegradation pathway and products toxicity of tetracycline in the system of Pt/BiVO4 nanosheets.

The antibiotics pollution has currently captured increasing concerns due to its potential hazards to the environment and human health. The development of efficient and viable techniques for the removal of antibiotics is one of the research hotspots in fields of wastewater treatment and pharmaceutical industry. Although the photodegradation of antibiotics is widely studied, the evolution and toxicity of degradation intermediates have been rarely documented. Herein, Pt nanoparticles (NPs) decorated BiVO4 nanosheets (Pt/BiVO4 NSs) that exhibit excellent tetracycline (TC) photodegradation activity and stability have been prepared. Especially, the TC degradation efficiency reaches ca. 88.5% after 60 min under visible light irradiation, which is superior to most of the metal loaded two-dimensional photocatalysts reported hitherto. The excellent photocatalytic activity is attributable to the enhanced light absorption capacity and charge separation efficiency in Pt/BiVO4 NSs. h+, •O2- and •OH are the main active species for TC degradation, resulting in three possible degradation pathways. Furthermore, we first verify that TC solutions treated by Pt/BiVO4 NSs are harmless to Escherichia coli K-12 and various bacteria in natural rivers, which would not stimulate Escherichia coli to produce antibiotics resistance genes (ARGs). This work develops an environmentally friendly photodegradation strategy using Pt/BiVO4 NSs with potentials for efficient remediation of antibiotics pollution in wastewater.

Synthesis of pyrimidines from dinitrogen and carbon.

The element nitrogen and nitrogenous compounds are vital to life. The synthesis of nitrogen-containing compounds using dinitrogen as the nitrogen source, not through ammonia, is of great interest and great value but remains a grand challenge. Herein, we describe a strategy to realize this transformation by combining the heterogeneous approach with the homogeneous methodology. The N2 molecule was first fixed with carbon and LiH through a one-pot heterogeneous process, forming Li2CN2 as an 'activated' nitrogen source with high efficiency. Then subsequent homogeneous treatments of Li2CN2 to construct the organic synthon carbodiimide and the RNA/DNA building block pyrimidines were fulfilled. By using 15N2 as the feedstock, their corresponding 15N-labeled carbodiimide and pyrimidines were readily obtained. This homogeneous-heterogeneous synergy strategy will open a new chapter for N2 transformation.

Assessing Ecological Vulnerability under Climate Change and Anthropogenic Influence in the Yangtze River Estuarine Island-Chongming Island, China.

Understanding and assessing ecological vulnerability for estuarine islands are important for maintaining estuarine island ecosystem services and its sustainable development. However, due to its complex fresh water-sea-land interaction mechanism and multiple stressors from both climate change and anthropogenic influence, a comprehensive evaluation of ecological vulnerability for estuarine islands has been limited. Therefore, taking the typical estuary island of Chongming Island as an example, we developed a comprehensive evaluation system of ecological vulnerability for an estuarine island ecosystem based on the pressure-state-response (PSR) conceptual model, and explored the spatial and temporal distribution of ecological vulnerability in 2005 and 2015. The results indicated that the main pressures of Chongming Island from saltwater intrusion intensity and land use intensity were mainly distributed in northern coastal areas and eastern areas of wetland; the ecological vulnerability index (EV) of Chongming Island showed a slight decrease from 2005 to 2015; and three categories of towns based on ecological vulnerability assessment for an eco-island planning and environmental management were identified. Our study provides an effective evaluation system of ecological vulnerability for estuarine islands, which could be helpful for planners and decision makers in improving eco-island planning and environmental management.

Spatiotemporal Change and the Natural-Human Driving Processes of a Megacity's Coastal Blue Carbon Storage.

Coastal blue carbon storage (CBCS) plays a key role in addressing global climate change and realizing regional carbon neutrality. Although blue carbon has been studied for some years, there is little understanding of the influence of a megacity's complex natural and human-driven processes on CBCS. Taking the Shanghai coastal area as an example, this study investigated the spatiotemporal change in CBCS using the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) model during 1990-2015, and analyzed the response of the CBCS to a megacity's complex natural- and human-driven processes through a land use/land cover transition matrix and hierarchical clustering. The results were as follows: (1) Thirty-three driving processes were identified in the study area, including four natural processes (e.g., accretion, succession, erosion, etc.), two human processes (reclamation and restoration) and twenty-seven natural-human coupled processes; they were further combined into single and multiple processes with positive and negative influences on the CBCS into four types (Mono+, Mono-, Multiple+ and Multiple- driving processes). (2) Shanghai's CBCS increased from 1659.44 × 104 Mg to 1789.78 ×104 Mg, though the amount of Shanghai's coastal carbon sequestration showed a decreasing trend in three periods: 51.28 × 104 Mg in 1990-2000, 42.90 × 104 Mg in 2000-2009 and 36.15 × 104 Mg in 2009-2015, respectively. (3) There were three kinds of spatiotemporal patterns in the CBCS of this study area: high adjacent to the territorial land, low adjacent to the offshore waters in 1990; high in the central part, low in the peripheral areas in 2009 and 2015; and a mixed pattern in 2000. These patterns resulted from the different driving processes present in the different years. This study could serve as a blueprint for restoring and maintaining the CBCS of a megacity, to help mitigate the conflicts between socioeconomic development and the conservation of the CBCS, especially in the Shanghai coastal area.