Infected Population Research Articles

Assessing the Importance of Theory-Based Correlates of Future HIV Vaccine Intentions Among Black Men Who Have Sex With Men.

In the United States, Black men who have sex with men (BMSM) represent the most vulnerable population for HIV infection. A potential vaccine could ultimately be the most effective HIV prevention strategy. Understanding the factors that may adversely affect HIV vaccine acceptance among BMSM is critical. We conducted two online surveys with BMSM; one recruited 432 respondents, and another recruited 204. Respondents completed a demographic assessment and questions derived from health behavior change theories and the relevant empirical literature. The two surveys yielded similar results. The findings indicate that vaccine uptake self-efficacy, perceived likelihood of important others receiving the vaccine, and susceptibility to HIV were related to intentions to receive a future HIV vaccine. Other potentially important variables include perceived HIV stigma, response efficacy, how much one conceals one's sexual orientation, and perceived HIV discrimination. Future research and health communication campaigns should consider these factors in potential HIV vaccine programs.

Evaluation of the application of Slovenia to be recognised as having a negligible risk of classical scrapie.

Slovenia submitted a request to the European Commission to be recognised as a Member State with negligible risk of classical scrapie. EFSA has been asked to assess if Slovenia has demonstrated that, between 2016 and 2022, a sufficient number of ovine and caprine animals over 18 months old, representative of those slaughtered, culled or found dead have been tested, and will continue to be tested annually, to provide a 95% confidence of detecting classical scrapie if it is present at a prevalence rate exceeding 0.1%. A risk-based approach using stochastic scenario tree modelling accounting for surveillance stream and species was applied. Globally, there is still a lack of data on the performance of the approved diagnostic screening tests under field conditions, specifically for sheep. Therefore, alternative scenarios were explored extending the range from the sensitivity (99.6%) provided by the past European Union evaluations to a sensitivity of 50%, more consistent with published data obtained under field conditions in infected goat populations. It was concluded that during the period 2016-2023, Slovenia has tested annually a sufficient number of ovine and caprine animals over 18 months of age, sourced from the NSHC and SHC populations, to ensure a 95% level of confidence of detecting CS if it is present in that population at a prevalence rate exceeding 0.1%, assuming a test sensitivity of 90% or above. The same holds for the years 2016, 2021 and 2023, assuming a test sensitivity of at least 80%. Based on the proposed number of samples for 2024 and future years, Slovenia would continue to meet the testing requirements assuming a test sensitivity of at least 80%.

New simple sequence repeat markers reveal undetected diversity in Spanish and Californian Diplodia sapinea populations

Diplodia sapinea is the causal agent of Diplodia shoot blight, an emerging disease affecting pine forests worldwide. The range expansion of this pathogen in northern Europe has been suggested to be partially facilitated by recent warmer conditions. Although D. sapinea has been studied extensively, critical aspects of its infection biology and population structure remain unexplored. In this study, we developed nine simple sequence repeat (SSR) markers mined from D. sapinea genomes to assess the genetic diversity at higher resolution. Isolates from northern Spain, an area formerly regarded as having low genetic diversity and samples from a Californian population that was formerly regarded as clonal, were analysed in the study. In Spain, the nine SSR markers identified 56 genotypes in 285 samples. Isolates from symptomatic shoots, cones and asymptomatic tissues collected from different stands, suggested admixture between local populations. The same genotype tended to dominate within a single cone, and the same genotypes were usually found in both symptomatic and asymptomatic shoot tissues. The nine new SSR markers developed in this study revealed a high level of genetic diversity in both the northern Spanish and northern Californian populations than previous anticipated. Analyses using these nine SSR markers should contribute to a better understanding of the epidemiology, evolution and origin of D. sapinea, a pathogen that is gaining prominence in many parts of the world.

Vitamin D Receptor Gene Polymorphisms Differentiated Between Tuberculosis Disease and Infection: Causal Association Study.

Latent tuberculosis infection (LTBI) is a critical stage in tuberculosis (TB)control, and few studies have addressed the role of vitamin D receptor(VDR) gene polymorphisms in differentiating between TB and late-onset TB from an immunogenetic perspective. Recruitment of tuberculosis patients and latently infected population in Urumqi, Xinjiang, and use of propensity score matching(PSM) to match the two groups and control confounding to further construct a Bayesian network to analyze causal associations between VDR polymorphisms and tuberculosis disease status. 137 LTBI and 237 TB were obtained through PSM. Logistic regression showed that the VDR gene BsmI locus, TaqI locus, and ApaI locus were associated with a higher risk of TB in a codominant model (P<0.05). Further Bayesian network construction showed that occupation and being a VDR gene BsmI locus were direct influences on TB disease status, and the VDR gene TaqI locus played an indirect role through the BsmI locus, and the probability of TB risk was highest in individuals with manual labour and BsmI locus of the C/T type, which was 84.15%. Bayesian network modelling intuitively revealed that individuals with a C/T type of BsmI locus and physical labour are at high risk of TB compared with TB infection, and they are key factors between with TB disease, providing reference evidence for controlling TB progression.

A Coupled Spatial-Network Model: A Mathematical Framework for Applications in Epidemiology.

There is extensive evidence that network structure (e.g., air transport, rivers, or roads) may significantly enhance the spread of epidemics into the surrounding geographical area. A new compartmental modeling framework is proposed which couples well-mixed (ODE in time) population centers at the vertices, 1D travel routes on the graph's edges, and a 2D continuum containing the rest of the population to simulate how an infection spreads through a population. The edge equations are coupled to the vertex ODEs through junction conditions, while the domain equations are coupled to the edges through boundary conditions. A numerical method based on spatial finite differences for the edges and finite elements in the 2D domain is described to approximate the model, and numerical verification of the method is provided. The model is illustrated on two simple and one complex example geometries, and a parameter study example is performed. The observed solutions exhibit exponential decay after a certain time has passed, and the cumulative infected population over the vertices, edges, and domain tends to a constant in time but varying in space, i.e., a steady state solution.

Hygienic requirements regarding to population safety for cancirogenic factors of biological nature (a review)

Objective: to identify the main trigger mechanisms of carcinogenic factors of biological nature and develop, on their basis, preventive measures to prevent the development of cancer in the population. Methodology for writing a review. A review 50 scientific papers posted in the databases Web of Science, Scopus, PubMed, CyberLeninka, eLibrary.ru were analyzed. The electronic search was carried out using a combination of keywords: "carcinogenic factors of biological nature", "viruses", "bacteria", "trematodes", "preventive work", "sanitary service", "oncological morality". The depth of searches in electronic databases and citation lists amounted to more than a 10-year period from 2013 to the middle of 2024. Conclusion. An analysis of the scientific literature showed that the trigger mechanisms in the pathogenesis of the formation of EIT caused by carcinogenic factors of biological nature lie in the ability of infectious pathogens to cause inflammatory reactions, turning into chronic infections that provoke the development of cancer among the infected population. Preventive measures, in the absence of specific vaccination, can be presented in the form of a set of preventive measures aimed at ensuring the sanitary, hygienic and anti-epidemiological well-being of the population.

NUMERICAL ASSESSMENT OF SOME SEMI-ANALYTICAL TECHNIQUES FOR SOLVING A FRACTIONAL-ORDER LEPTOSPIROSIS MODEL

This research aims to apply and compare two semi-analytical techniques, the Variational Iterative Method (VIM) and the New Iterative Method (NIM), for solving a pre-formulated mathematical model of Fractional-order Leptospirosis. Leptospirosis is a significant bacterial infection affecting humans and animals. By implementing the VIM and NIM algorithms, numerical experiments are conducted to solve the leptospirosis model. Comparing the obtained findings demonstrates that VIM and NIM are effective semi-analytical methods for solving systems of fractional differential equations. Notably, our study unveils a crucial dynamic in the disease's spread. The application of VIM and NIM offers a refined depiction of the biological dynamics, highlighting that the susceptible human population gradually decreases, the infectious human population declines, the recovered human population increases, and a significant rise in the infected vector population is observed over time. This nuanced portrayal of the disease's dynamics is crucial for understanding the intricate interplay of Leptospirosis among human and vector populations. The study's outcomes contribute valuable insights into the applicability and performance of the methods in solving the Fractional Leptospirosis model. Results indicate rapid convergence and comparable outcomes for both methods.

Efficacy and safety of vancomycin compared with those of alternative treatments for methicillin-resistant Staphylococcus aureus infections: An umbrella review.

To summarize the evidence on the efficacy and safety of vancomycin compared with those of alternative treatments in adult patients with methicillin-resistant Staphylococcus aureus (MRSA) infection. PubMed, Embase, and Web of Science were searched up to December 15, 2023, for systematic reviews and meta-analyses comparing vancomycin with alternative MRSA treatments. Primary outcomes included clinical cure and microbiological eradication rates. Organ-specific safety outcomes were assessed. Summary estimates were recalculated using a random-effects model. Evidence was graded using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) tool. This study was registered in PROSPERO (CRD42022340359). This umbrella review included 19 studies and 71 meta-analyses (46 efficacy and 25 safety) comparing vancomycin with 10 alternative treatments across different MRSA infection types and populations. GRADE assessment showed that 29.58% of the meta-analyses were of high quality. Linezolid and daptomycin showed higher efficacy in MRSA-induced skin and soft tissue infections and pneumonia (moderate evidence quality) and bacteremia (very low evidence quality), respectively, compared with that of vancomycin. Cephalosporins had a higher risk of nausea, whereas linezolid had a higher risk of nausea, diarrhea, and thrombocytopenia than that of vancomycin. Vancomycin posed a higher risk of rash, pruritus, red man syndrome, and nephrotoxicity than that of alternatives. The quality of evidence supporting the higher efficacy of alternative treatment over vancomycin for MRSA infection was not high. Given varying safety profiles and advancements in therapeutic monitoring, careful consideration of patient-specific factors and pharmacokinetics is crucial when selecting treatment alternatives to vancomycin.

Epidemiological changes of scarlet fever before, during and after the COVID-19 pandemic in Chongqing, China: a 19-year surveillance and prediction study

BackgroundThis study aimed to investigate the epidemiological changes in scarlet fever before, during and after the COVID-19 pandemic (2005–2023) and predict the incidence of the disease in 2024 and 2025 in Chongqing Municipality, Southwest China.MethodsDescriptive analysis was used to summarize the characteristics of the scarlet fever epidemic. Spatial autocorrelation analysis was utilized to explore the distribution pattern of the disease, and the seasonal autoregressive integrated moving average (SARIMA) model was constructed to predict its incidence in 2024 and 2025.ResultsBetween 2005 and 2023, 9,593 scarlet fever cases were reported in Chongqing, which resulted in an annual average incidence of 1.6694 per 100,000 people. Children aged 3–7 were the primary victims of this disease, with the highest average incidence found among children aged 6 (5.0002 per 100,000 people). Kindergarten children were the dominant infected population, accounting for as much as 54.32% of cases, followed by students (34.09%). The incidence for the male was 1.51 times greater than that for the female. The monthly distribution of the incidence showed a bimodal pattern, with one peak occurring between April and June and another in November or December. The spatial autocorrelation analysis revealed that scarlet fever cases were markedly clustered; the areas with higher incidence were mainly concentrated in Chongqing’s urban areas and its adjacent districts, and gradually spreading to remote areas after 2020. The incidence of scarlet fever increased by 106.54% and 39.33% in the post-upsurge period (2015–2019) and the dynamic zero-COVID period (2020–2022), respectively, compared to the pre-upsurge period (2005–2014) (P < 0.001). During the dynamic zero-COVID period, the incidence of scarlet fever decreased by 68.61%, 25.66%, and 10.59% (P < 0.001) in 2020, 2021, and 2022, respectively, compared to the predicted incidence. In 2023, after the dynamic zero-COVID period, the reported cases decreased to 1.5168 per 100,000 people unexpectedly instead of increasing. The cases of scarlet fever are predicted to increase in 2024 (675 cases) and 2025 (705 cases).ConclusionsChildren aged 3–7 years are the most affected population, particularly males, and kindergartens and primary schools serving as transmission hotspots. It is predicted that the high incidence of scarlet fever in Chongqing will persist in 2024 and 2025, and the outer districts (counties) beyond urban zone would bear the brunt of the impact. Therefore, imminent public health planning and resource allocation should be focused within those areas.

A reliable qPCR technique for detecting viable Xanthomonas arboricola pv. pruni cells

Xanthomonas arboricola pv. pruni (Xap) is the causal agent of bacterial spot of stone fruits and almond (Prunus spp). Detection of Xap is typically carried out using quantitative real-time PCR (qPCR) combined with culture-based isolation. However, qPCR does not differentiate between viable and dead cells, potentially leading to an overestimation of the infective population in a sample. Such overestimation could result in unnecessary phytosanitary measures. The present study aims to develop a specific protocol ideally targeting to detection of only live Xap bacterial cells. To address this challenge, the viable quantitative PCR (v-qPCR) method was evaluated using three nucleic acid-binding dyes: propidium monoazide (PMA), a combination of PMA and ethidium monoazide (EMA), and PMAxx™, an improved version of PMA. PMAxx™ proved to be the most suitable dye for the detection and quantification of living bacterial cells. This methodology was also evaluated in infected plant material over time and can be considered a rapid and reliable alternative to PCR methods for detecting only those putative infective Xap that may pose a risk for Prunus crops.Key points• Protocol to detect biofilm and planktonic viable X. arboricola pv. pruni cells.• Host validated protocol.• Benefits, reduction of chemicals in disease control.

Untangling the mobility dynamics in a patchy environment: An SEIR epidemic model with vertical transmission

Congenital Rubella, AIDS, and other human diseases may pass from mother to fetus through the placenta. On the other side, insects and plants often transmit vertically by their eggs/seeds. Here, we study an SEIR epidemic model with vertical transmission in a multi‐patch context to explore the spread of disease in a population divided into distinct regions. The local and global stability of disease‐free equilibrium for the n‐patch model system has been determined in terms of the basic reproduction number . Moreover, we discuss the existence and stability of endemic equilibrium for different cases in two symmetric regions. Our findings indicate that when is less than one, the disease‐free equilibrium is globally asymptotically stable, whereas when is greater than one, it is unstable. As a result, for , the model system has an unique endemic equilibrium that is always locally asymptotically stable. The dynamics of the proposed model system depending on the distribution of infected individuals across various regions have been studied. The findings suggest that the movements from high disease risk regions to low disease risks may increase the number of the infected population in the community. The value of could be enhanced by increasing the values of any vertical transmission parameter. However, the changes in the values of are relatively minor. Our findings also imply that while migrations of all individuals across symmetric regions do not leave any impact on the equilibrium state of the infected population, they do affect the trajectory of the solution to reach a steady‐state. The flow of people between the two symmetrical regions could not alter the endemicity.

Proposition of a novel SIRS epidemic model with double epidemics and coexisting epidemics

Improving epidemic models to better reflect reality has long been a prominent concern for governments and researchers. This paper presents a novel Susceptible–Infected–Recovered–Susceptible (SIRS) epidemic model for human populations, offering a comprehensive analysis. The proposed model introduces a generalized SIRS epidemics framework encompassing three propagation scenarios. The paper establishes the positivity and boundedness of the system and demonstrates the stability of its equilibrium points. Furthermore, a controlled system is introduced, accompanied by three suggested control strategies to minimize the infected population while optimizing cost. To validate the analytical findings, a numerical example is provided. The paper concludes with a summary and outlines future research directions.

Human papillomavirus molecular prevalence in south China and the impact on vaginal microbiome of unvaccinated women.

In this study, we first investigated the prevalence of different HPV genotypes in south China, which could provide more information for HPV vaccinations. Then, a total of 185 subjects were selected from HPV-negative, high-risk, low-risk, multiple hr-hr HPV infection, and mixed hr-lr HPV infection populations to explore the vaginal microbiome changes. This study displayed that HPV52, HPV58, and HPV16 were the most prevalent high-risk variants in south China. In addition, high-risk HPV infection was featured by Lactobacillus iners, while low-risk HPV infection was by Lactobacillus crispatus. Further sub-group analysis showed that Lactobacillus jensenii was significantly reduced in patients with cervical lesions. Finally, CST clustering showed that CST IV was the most common type in HC group, while CST I accounted the most in H group. In a word, this study for the first time systemically profiled vaginal microbiome of different HPV infections, which may add bricks to current knowledge on HPV infection and lay the foundation for novel treatment/prevention development.

Microglia and macrophages alterations in the CNS during acute SIV infection: A single-cell analysis in rhesus macaques.

Human Immunodeficiency Virus (HIV) is widely acknowledged for its profound impact on the immune system. Although HIV primarily affects peripheral CD4 T cells, its influence on the central nervous system (CNS) cannot be overlooked. Within the brain, microglia and CNS-associated macrophages (CAMs) serve as the primary targets for HIV and the simian immunodeficiency virus (SIV) in nonhuman primates. This infection can lead to neurological effects and establish a viral reservoir. Given the gaps in our understanding of how these cells respond in vivo to acute CNS infection, we conducted single-cell RNA sequencing (scRNA-seq) on myeloid cells from the brains of three rhesus macaques 12 days after SIV infection, along with three uninfected controls. Our analysis revealed six distinct microglial clusters including homeostatic microglia, preactivated microglia, and activated microglia expressing high levels of inflammatory and disease-related molecules. In response to acute SIV infection, the homeostatic and preactivated microglia population decreased, while the activated and disease-related microglia increased. All microglial clusters exhibited upregulation of MHC class I molecules and interferon-related genes, indicating their crucial roles in defending against SIV during the acute phase. All microglia clusters also upregulated genes linked to cellular senescence. Additionally, we identified two distinct CAM populations: CD14lowCD16hi and CD14hiCD16low CAMs. Interestingly, during acute SIV infection, the dominant CAM population changed to one with an inflammatory phenotype. Specific upregulated genes within one microglia and one macrophage cluster were associated with neurodegenerative pathways, suggesting potential links to neurocognitive disorders. This research sheds light on the intricate interactions between viral infection, innate immune responses, and the CNS, providing valuable insights for future investigations.

Central Nervous System Infections in Patients With Ventriculoperitoneal Shunts Admitted for Primary Abdominal Infections: A US Nationwide Cohort Analysis.

Although ventriculoperitoneal (VP) shunts are a common treatment for hydrocephalus, there are complication risks including infections. Late complications such as ventriculitis from ascending abdominal infections can have severe consequences. However, the incidence of central nervous system (CNS) infections in VP shunt patients with abdominal infections is not well understood. We aimed to determine the incidence of CNS infections in VP shunt patients admitted with abdominal infections. Using the National Inpatient Sample, we studied patients from 2016 to 2019 to determine the incidence of CNS infections in VP shunt patients admitted with abdominal infections. Results were compared with VP shunt patients admitted for primary pneumonia. Among 725 VP shunt patients presenting with abdominal infections, 20 (2.8%) had CNS infections. Chronic obstructive pulmonary disease, hypertension, older age, and a smoking history were more common in patients with CNS infections and primary abdominal infection (P < .05). Patients who developed CNS infection had a significantly higher likelihood of both blood transfusion and coma but a lower likelihood of seizures. VP shunt patients with CNS infections were more likely to undergo shunt removal (odds ratio [OR] = 23.167, P < .001). 4.1% of VP shunt patients with primary abdominal infections died during admission. In a population of primary abdominal infection and pneumonia patients with VP shunts, a multivariate logistic regression analysis controlling for age, sex, and comorbidities identified abdominal infection as an independent risk factor for both CNS infection (OR = 51.208, P < .001) and inpatient death (OR = 3.417, P < .001). Among 6620 VP shunt patients admitted with primary pneumonia, only 5 (0.1%) had CNS infection compared with 20 (2.8%) in those with a primary abdominal infection (OR = 37.532, P < .001), and mortality was 1.6% vs 4.1% for those with a primary abdominal infection (P < .05). CNS infections in VP-shunted patients with abdominal infections are relatively rare but may lead to increased risks of death and other serious adverse outcomes.

Molecular epidemiology of SARS-CoV-2 genome sentinel surveillance in commercial COVID-19 testing sites targeting asymptomatic individuals during Japan’s seventh epidemic wave

Eight peaks of coronavirus disease 2019 (COVID-19) outbreak occurred in Japan, each associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern. The National Epidemiological Surveillance of Infectious Diseases (NESID) analyzed viral genome sequences from symptomatic patients and submitted the results to GISAID. Meanwhile, commercial testing services occasionally sequence samples from asymptomatic individuals. We compared a total of 1248 SARS-CoV-2 full-genome sequences obtained from the SB Coronavirus Inspection Center Corp. (SBCVIC) during Japan’s seventh wave, which was dominated by Omicron variants, with 1764 sequences obtained in Japan from GISAID during the same period using chronological phylogenies and molecular transmission networks. The number of SBCVIC sequences was consistent with the number of cases reported by NESID. The SBCVIC detected a shift in the PANGO lineage from BA.2 to BA.5 earlier than that of GISAID. BA.2 lineages from the SBCVIC were distributed at different locations in the transmission network dominated by GISAID entries, whereas BA.5 lineages from SBCVIC and GISAID often formed distinct subclusters. Test-based sentinel surveillance of asymptomatic individuals may be a more manageable approach compared to notifiable disease surveillance; however, it may not necessarily capture all infection populations throughout Japan.

Drivers of diversification in fungal pathogen populations.

To manage and treat chronic fungal diseases effectively, we require an improved understanding of their complexity. There is an increasing appreciation that chronic infection populations are often heterogeneous due to diversification and drift, even within a single microbial species. Genetically diverse populations can contribute to persistence and resistance to treatment by maintaining cells with different phenotypes capable of thriving in these dynamic environments. In chronic infections, fungal pathogens undergo prolonged challenges that can drive trait selection to convergent adapted states through restricted access to critical nutrients, assault by immune effectors, competition with other species, and antifungal drugs. This review first highlights the various genetic and epigenetic mechanisms that promote diversity in pathogenic fungal populations and provide an additional barrier to assessing the actual heterogeneity of fungal infections. We then review existing studies of evolution and genetic heterogeneity in fungal populations from lung infections associated with the genetic disease cystic fibrosis. We conclude with a discussion of open research questions that, once answered, may aid in diagnosing and treating chronic fungal infections.

Smart waterborne disease control for a scalable population using biodynamic model in IoT network

We propose a biodynamic model for managing waterborne diseases over an Internet of Things (IoT) network, leveraging the scalability of LoRa IoT technology to accommodate a growing human population. The model, based on fractional order derivatives (FOD), enables smart prediction and control of pathogens that cause waterborne diseases using IoT infrastructure. The human-pathogen-based biodynamic FOD model utilises epidemic parameters (SVIRT: susceptibility, vaccination, infection, recovery, and treatment) transmitted over the IoT network to predict pathogenic contamination in water reservoirs and dumpsites in Iji-Nike, Enugu, the study community in Nigeria. These pathogens contribute to person-to-person, water-to-person, and dumpsite-to-person transmission of disease vectors. Five control measures are proposed: potable water supply, treatment, vaccination, adequate sanitation, and health education campaigns. A stable disease-free equilibrium point is found when the effective reproduction number of the pathogens, R0eff<1 and unstable if R0eff>1. While other studies showed a 98.2% reduction in infections when using IoT alone, this paper demonstrates that combining the SVIRT epidemic control parameters (such as potable water supply and health education campaign) with IoT achieves a 99.89% reduction in infected human populations and a 99.56% reduction in pathogen populations in water reservoirs. Furthermore, integrating treatment with sanitation results in a 99.97% reduction in infected populations. Finally, combining these five control strategies nearly eliminates infection and pathogen populations, demonstrating the effectiveness of multifaceted approaches in public health and environmental management. This study provides a blueprint for governments to plan sustainable smart cities for a growing population, ensuring potable water free from pathogenic contamination,in line with the United Nations Sustainable Development Goals #6 (Clean Water and Sanitation) and #11 (Sustainable Cities and Communities).

Post-vaccination, post-infection and hybrid immunity against severe cases of COVID-19 and long COVID after infection with SARS-CoV-2 Omicron subvariants, Czechia, December 2021 to August 2023.

BackgroundCOVID-19 remains a major infectious disease with substantial implications for individual and public health including the risk of a post-infection syndrome, long COVID. The continuous changes in dominant variants of SARS-CoV-2 necessitate a careful study of the effect of preventative strategies.AimWe aimed to estimate the effectiveness of post-vaccination, post-infection and hybrid immunity against severe cases requiring oxygen support caused by infections with SARS-CoV-2 variants BA1/2 and BA4/5+, and against long COVID in the infected population and their changes over time.MethodsWe used a Cox regression analysis with time-varying covariates and calendar time and logistic regression applied to national-level data from Czechia from December 2021 until August 2023.ResultsRecently boosted vaccination, post-infection and hybrid immunity provide significant protection against a severe course of COVID-19, while unboosted vaccination more than 10 months ago has a negligible protective effect. The post-vaccination immunity against the BA1/2 or BA4/5+ variants, especially based on the original vaccine types, appears to wane rapidly compared with post-infection and hybrid immunity. Once infected, however, previous immunity plays only a small protective role against long COVID.ConclusionVaccination remains an effective preventative measure against a severe course of COVID-19 but its effectiveness wanes over time thus highlighting the importance of booster doses. Once infected, vaccines may have a small protective effect against the development of long COVID.

Optimal control with the effects of ivermectin and live stock availability on malaria transmission

Malaria remains a global threat and the conventional methods used for combating the disease leave out mosquitoes that feed outdoors. This study addresses the challenge posed by such mosquitoes based on a tool called ivermectin drug which is lethal to mosquitoes that ingest bloodmeal containing a concentration of it. We formulated a mathematical model with three control tools (insecticide treated nets, treatment of infective individuals and ivermectin drug on livestock and humans) for the transmission and control of malaria under optimal condition. The model’s basic reproduction number, R0 was estimated and the local and global stability analyses of the disease-free and endemic equilibrium points of the model were carried out. Sensitivity analysis carried out showed that R0 is most sensitive to the mosquito biting rate and to the proportion of blood meal on human with cattle availability in such a way that any percent increase in the value of any of these parameters will lead to an equal percent increase in the value of R0. The result of an optimal control analysis based on three time dependent controls suggests that the combination of all three controls gives the best result followed by the strategy that combines the use of ivermectin drug and the treatment of infective human. Depending on available resources, any of these is recommended to be adopted in malaria intervention programmes because of their effectiveness on both the infective human and mosquito populations with the potential of contributing significantly to the disease elimination within a minimal time frame.