Search Results (131)

Background: Annual influenza vaccine updates target viral drift, but immune responses may be biased by original antigenic sin (OAS). Few studies have explored this across closely related strains. This study examines how OAS shapes responses to sequential influenza variants in the context of seasonal vaccination. Methods: We conducted a prospective, longitudinal study to assess the humoral immune response to the 2023–2024 seasonal influenza vaccine containing the A/Victoria/4897/2022 (H1N1) strain. Bioinformatic analyses compared the hemagglutinin (HA) sequences of A/Victoria/4897/2022 and the antigenically related A/Victoria/2570/2019 strain. B-cell epitopes were mapped with BepiPred-3.0 and BepiBlast, and their physicochemical properties analyzed via accessibility, β-turns, flexibility, and hydrophilicity. Antibody responses were measured pre- and 28 days post-Vaxigrip Tetra vaccination in young (18–35) and older (>65) adults, stratified by cytomegalovirus (CMV) serostatus. HA sequences showed >97% identity, with variations mainly in the globular head. Predicted B-cell epitopes overlapped variable sites, suggesting possible immune escape. Despite having been vaccinated against the 2022 strain, serology showed higher antibody titers against the 2019 HA strain in all participants. This pattern suggests a potential antigen imprinting effect, though confirmation awaits further analysis. Age groups differed: older adults showed greater variability, while younger CMV+ individuals tended toward stronger 2019 HA responses. Conclusions: These findings suggest a complex interplay of factors shaping immune responses, though the imprinting effect and the potential role of CMV warrant further exploration in larger, more focused studies. Full article

The COVID-19 pandemic is a catastrophic event highlighting numerous health disparities. The social vulnerability index (SVI) has been widely utilized in COVID-19 research to assess vulnerable communities and to examine how social determinants influence various COVID-19 outcomes. This population-based study aims to determine whether COVID-19 testing and vaccination rates mediate the relationship between the SVI and COVID-19 prevalence. Mediation analysis was conducted using data from 535 census tracts in Clark County, Nevada. Findings indicate that COVID-19 testing rates were lower in areas with high SVI scores, potentially leading to more undetected cases. Moreover, COVID-19 testing, full vaccination, and follow-up vaccination rates significantly mediated the relationship between SVI and COVID-19 prevalence. These results suggest that greater location-based social vulnerability is associated with a sequential pathway of reduced testing and vaccination rates, contributing to underreported COVID-19 cases. Full article

Streptococcus pneumoniae remains the leading cause of community-acquired pneumonia in adults and bacterial meningitis in children worldwide. In addition to pneumonia, invasive pneumococcal diseases (IPDs), such as bacteremia and meningitis, pose a significant burden, particularly among older adults and individuals with underlying comorbidities. These diseases lead to substantial morbidity and mortality. Pneumococcal vaccination has been a cornerstone of disease prevention, reducing incidence and antimicrobial resistance. Recent advances in understanding S. pneumoniae epidemiology, genomic diversity, and the real-world impact of conjugate vaccines have driven the development and licensure of new-generation pneumococcal vaccines with expanded serotype coverage. Introducing 15-valent (PCV15), 20-valent (PCV20), and 21-valent (PCV21) conjugate vaccines has reshaped pneumococcal immunization strategies, particularly in adults, replacing previous sequential vaccine recommendations in many settings. In parallel, emerging epidemiological data and shifts in pneumococcal serotype distribution continue to influence vaccine policy decisions and immunization guidelines worldwide. In light of these advancements, adult pneumococcal vaccination recommendations continuously evolve to enhance protection in high-risk populations and optimize long-term immunity. This review provides an updated overview of the pneumococcal disease burden, the evolution of pneumococcal vaccines, and the latest immunization strategies in an expanding vaccine landscape. Additionally, we discuss future directions in pneumococcal vaccine development and the potential impact of novel vaccination approaches on public health outcomes. Full article

Background/Objectives: Developing durable cellular immunity remains a critical challenge for HIV vaccine development. Methods: We evaluated a sequential and repeated heterologous prime–boost vaccination regimen using four distinct vector-based vaccines (DNA, rAd5, rSeV, and rMVA) expressing HIV-1 gag in rhesus macaques over a decade-long observation period. Results: Compared to the two-vector and control groups, the four-vector regimen elicited potent gag-specific cellular immune responses, as evidenced by IFN-γ ELISPOT assays showing sustained responses exceeding 500 SFCs/10⁶ PBMCs for up to 52 or 69 weeks post-vaccination. Intracellular cytokine staining revealed multifunctional CD4+ and CD8+ T-cell responses, while humoral immunity against Ad5 vectors remained manageable despite repeated administrations. Conclusions: These findings demonstrate that sequential and repeated heterologous vaccination effectively induces and maintains durable cellular immunity, providing a strategic framework for HIV vaccine design. Full article

Background/Objectives: Novel mRNA vaccines have been successfully utilized to curtail the SARS-CoV-2 pandemic. However, the immunology underlying CoV2 vaccinations, particularly with repeated boosting, has not been properly characterized due to limitations in the preclinical modeling of SARS-CoV-2 infection/vaccinations as well as constantly changing vaccine formulations. The immunoregulatory aspects involved in such vaccine approaches remain unclear. Antibodies, due to inherent immunogenicity by VDJ gene rearrangement, have the potential to induce antibodies directed towards them called anti-idiotype antibodies, which can play a downregulatory role in responses. The paratope of some of these anti-idiotype antibodies can also act as a mirror to the original antigen, which, in the case of SARS-CoV-2 vaccines, would be to the spike protein and, therefore, also be capable of binding its target, ACE2, potentially causing adverse effects. Methods: To investigate if sequential SARS-CoV-2 mRNA vaccination can induce anti-idiotype antibody responses, K18 hACE2 transgenic mice were serially vaccinated with a SARS-CoV-2 mRNA construct to determine the kinetics of anti-spike and anti-ACE2 responses via custom-made ELISAs. Results: While sequential vaccination produced robust anti-spike responses, anti-ACE2 levels were also detected and gradually amplified with each boost. These anti-ACE2 antibodies persisted for 3 months after the final vaccination and showed evidence of hACE2 binding, as levels were lower in K18 mice in comparison to the wild type. Conclusions: These data would suggest that sequential SARS-CoV-2 mRNA vaccination has the potential to induce anti-ACE2 antibodies in mice, with each boost amplifying the amount of antibody. Full article

(1) Background: Rotavirus (RV) is the primary pathogen causing diarrhea in infants and young children. The G9-type is an emerging genotype; however, its isolation is challenging, and its immunogenicity to piglets is poorly understood. This study aimed to isolate, characterize, and evaluate the immunogenicity of a PoRVA strain, RHeN2, obtained from the diarrhea samples of piglets from a pig farm in Henan Province, China. (2) Methods: Porcine rotavirus A (PoRVA) was isolated from diarrheal samples of piglets on a farm in Henan Province, China, through sequential passaging on MA-104 cells. Its immunogenicity and cross-neutralization potential were evaluated. Inactivated vaccines were prepared using two agents (formaldehyde and binary ethyleneimine, BEI) and administered intramuscularly to 28-day-old piglets. Dulbecco’s Modified Eagle Medium (DMEM) served as the control. (3) Results: A PoRVA strain, G9P[23] type, was successfully isolated and named RHeN2. Full-genome Sanger sequencing revealed the genetic constellation of this strain as G9-P[23]-I5-R1-C1- M1-A8-N1-T1-E1-H1. In addition, the titers of neutralizing antibodies peaked at 45 days post-vaccination, and the immunogenicity of the BEI-inactivated group of vaccines was better than that of the formaldehyde-inactivated group. The RHeN2 (G9P[23]) strain demonstrated a strong cross-neutralization ability against the same G9P[23] and G4P[23] strains and a stronger cross-neutralizing ability against the P[23] strains than against the P[7] strains. (4) Conclusion: The newly isolated G9P[23] strain demonstrates favorable immunogenicity, holding potential as a G9-type vaccine candidate. Full article

Background/Objectives: Streptococcus pneumoniae with, or following, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been associated with increased mortality, particularly in older adults. However, vaccination can be an effective preventative measure. This Phase 3 study (NCT05158140) assessed the immunogenicity and safety of co-administering the SARS-CoV-2 vaccine mRNA-1273 with the 23-valent pneumococcal polysaccharide vaccine (PPSV23) or the 15-valent pneumococcal conjugate vaccine (PCV15). Methods: Participants were healthy adults ≥50 years of age who had previously received a two-dose primary series of mRNA-1273 ≥5 months before the first study visit and may have received a booster dose of mRNA-1273 ≥4 months prior to the first study visit. Participants were randomized (1:1:1:1) to receive mRNA-1273 concomitantly with PPSV23 or PCV15 on Day 1 followed by placebo on Day 30, or sequentially with mRNA-1273 and placebo on Day 1 and PPSV23 or PCV15 on Day 30. The primary study endpoints were pneumococcal-serotype-specific opsonophagocytic activity (OPA) geometric mean titers (GMTs) and SARS-CoV-2-specific binding antibody GMTs at 30 days after vaccination, as well as safety and tolerability following vaccination. Results: In total, 850 adults participated in the study. Serotype-specific OPA GMTs at 30 days post-vaccination with PPSV23 or PCV15 were generally comparable between the concomitant and sequential groups. SARS-CoV-2-specific GMTs increased in all groups from pre-vaccination to 30 days post-vaccination with mRNA-1273, with a consistent response between concomitant and sequential groups. Safety profiles were comparable across study groups. Conclusions: Co-administration of mRNA-1273 with PPSV23 or PCV15 in healthy adults ≥50 years of age was immunogenic and well tolerated. Full article

The COVID-19 pandemic has generated a vast corpus of online conversations regarding vaccines, predominantly on social media platforms like X (formerly known as Twitter). However, analyzing sentiment in Arabic text is challenging due to the diverse dialects and lack of readily available sentiment analysis resources for the Arabic language. This paper proposes an explainable Deep Learning (DL) approach designed for sentiment analysis of Arabic tweets related to COVID-19 vaccinations. The proposed approach utilizes a Bidirectional Long Short-Term Memory (BiLSTM) network with Multi-Self-Attention (MSA) mechanism for capturing contextual impacts over long spans within the tweets, while having the sequential nature of Arabic text constructively learned by the BiLSTM model. Moreover, the XLNet embeddings are utilized to feed contextual information into the model. Subsequently, two essential Explainable Artificial Intelligence (XAI) methods, namely Local Interpretable Model-Agnostic Explanations (LIME) and SHapley Additive exPlanations (SHAP), have been employed for gaining further insights into the features’ contributions to the overall model performance and accordingly achieving reasonable interpretation of the model’s output. Obtained experimental results indicate that the combined XLNet with BiLSTM model outperforms other implemented state-of-the-art methods, achieving an accuracy of 93.2% and an F-measure of 92% for average sentiment classification. The integration of LIME and SHAP techniques not only enhanced the model’s interpretability, but also provided detailed insights into the factors that influence the classification of emotions. These findings underscore the model’s effectiveness and reliability for sentiment analysis in low-resource languages such as Arabic. Full article

Background: Elite-neutralizer-derived HIV-1 envelopes (Envs), which induce broadly neutralizing antibodies (bnAbs), can inform HIV-1 vaccine design by serving as templates for bnAb-eliciting vaccines. Since single Env-based immunizations are insufficient to induce bnAb responses, sequential regimens using multivalent immunogens or Env cocktails hold greater promise. This underscores the need to develop stable Env trimers from diverse HIV-1 strains, particularly clade-C, which accounts for 50% of global infections and over 90% in India and South Africa. While various platforms exist to stabilize soluble Env trimers for use as antigenic baits and vaccines, stabilizing clade C trimers remains challenging. Methods: We stabilized an HIV-1 clade C trimer based on an Env isolated from a pediatric elite neutralizer (AIIMS_329) using multiple platforms, including SOSIP.v8.2, ferritin nanoparticles (NPs) and I53-50 two-component NPs, followed by characterization of their biophysical, antigenic, and immunogenic properties. Results: The stabilized 329 Envs showed binding to multiple HIV-1 bnAbs, with negligible binding to non-neutralizing antibodies. Negative-stain electron microscopy confirmed the native-like conformation of the Envs. Multimerization of 329 SOSIP.v8.2 on ferritin and two-component I53-50 NPs improved the affinity to HIV-1 bnAbs and showed higher immunogenicity in rabbits. Conclusions: The soluble 329 Env protein could serve as an antigenic bait, and multimeric 329 NP Envs are potential vaccine candidates. Full article

Background/Objectives: Rapid cycle analysis (RCA) is an established and efficient methodology that has been traditionally utilized by United States health authorities to monitor post-approval vaccine safety. Initially developed in the Vaccine Safety Datalink (VSD) in early 2000s, RCA has evolved into a valuable approach for timely post-approval signal detection. Due to the availability of additional near real-time data sources and enhanced analytic approaches, the use of RCA has expanded. This narrative review provides an in-depth assessment of studies that utilized RCA for safety surveillance to detect and evaluate safety signals in post-approval vaccine monitoring. Methods: Embase and Medline were searched on 8 August 2024 to identify post-approval non-interventional vaccine safety studies using RCA or other near real-time surveillance methods published from 1 January 2018 to 31 July 2024. Data on study characteristics (e.g., study population, data source, outcomes) and RCA methodological characteristics (e.g., type of comparator, sequential testing method, confounding control method) were extracted from the eligible RCA studies. Results: Of 1128 articles screened, 18 RCA vaccine safety studies were included, of which 17 (94.4%) were conducted in the United States (US). Twelve (67%) aimed at signal detection and six (33%) conducted further signal evaluation. Over 60% examined COVID-19 vaccine safety, with half using VSD. Over 80% conducted the RCA weekly or monthly and about 78% of the studies used a database-specific historical comparator group. Conclusions: This review indicates that most of the published articles on the application of the RCA methodology in vaccine safety studies are based on research conducted in the US. With increasing availability of near real-time data sources and advanced analytic methods capabilities, RCA is expected to be more widely deployed as an active surveillance tool to complement traditional pharmacovigilance. Future studies should explore the extension of vaccine RCA methodology for non-vaccine medicinal products. Full article

Introduction: Variants of COVID-19 are responsible for 700 million infections and 7 million deaths worldwide. Vaccinations have high efficiency in preventing infection and secondary benefits of reducing COVID-19 hospital admissions, attenuating disease severity and duration of illness. Conflicting reports were published regarding COVID-19 among PLWH. Objective: The aim of this study was to evaluate COVID-19 morbidity, hospitalization, and the magnitude of immunological response to sequential BNT 162b2 mRNA vaccines in PLWH regarding demographic and clinical factors. Results: Our retrospective study included 784 PLWH who had at least one anti- SARS-CoV-2 antibody test between March 2021 and October 2021. Half of our patients (392) had CD4 cell counts above 500 cells/µL, 40.2% (315) had 200 < CD4 < 500 cells/µL and only 9.8% (77) had CD4 < 200 cells/µL at their last laboratory workup. The mean age was 50.2 ± 12.2 years. About 90% of our patients were given at least two doses of the BNT 162b2 Pfizer vaccines; about 60% received three doses of the vaccine. About a quarter of our patients (27.6%) had COVID-19 infection. Only six patients required hospital admission. All six patients recovered from COVID-19 infection. Titers of COVID-19 antibodies were lower for patients with CD4 cell counts of less than 200 cells/µL in the first, second, and third serological tests with statistical significance. In a multinomial logistic regression, the influence of other factors such as age, sex, and previous COVID-19 infection on first COVID-19 antibody titers was not significant. Conclusions: PLWH are responsive to COVID-19 vaccines. As was expected, patients with higher CD4 cell counts had higher titers of COVID-19 antibodies and lower hospitalization rate. Age, sex, and previous COVID-19 infection did not significantly affect antibody titers according to our study. Larger prospective studies with control groups are needed to further characterize immunologic response to COVID-19 vaccination among PLWH. Full article

Background: Vaccination against Streptococcus pneumoniae is advised for transplant recipients to reduce morbidity and mortality associated with invasive pneumococcal disease. However, data on alloantibodies after sequential vaccination (with a pneumococcal conjugate vaccine followed by a polysaccharide vaccine) are still lacking. Methods: In the current study, we determined HLA class I and II and major histocompatibility class I-related chain A (MICA) antibodies in 41 clinically stable kidney transplant recipients. These antibodies were measured prior to and post sequential pneumococcal vaccination over a period of 12 months. Alloantibodies were measured by Luminex bead-based assays, and pneumococcal IgG antibodies were measured by ELISA. Results: Over a 12-month period, the sequential analysis revealed no significant change in alloantibodies. One patient developed de novo donor-specific antibodies (DSA) 1.5 months after the first vaccination, with mean fluorescence intensities of up to 2300. These DSA became undetectable in the follow-up, and the patient showed no signs of allograft rejection. Another patient experienced a biopsy-proven borderline rejection 7 months after the first vaccination but did not develop de novo DSA. Both maintained stable kidney function. As expected, the pneumococcal antibodies increased significantly after vaccination (p < 0.0001). Conclusions: Given the overall risk of alloimmune responses in transplant recipients, we would not attribute the two noticeable patient courses to vaccination. Thus, we consider sequential vaccination immunologically safe. Full article

The COVID-19 pandemic prompted the rapid development of vaccines, including the ChAdOx1 nCov-19 (AstraZeneca) vaccine. While effective, adverse effects have been reported, including cutaneous manifestations. Kaposi sarcoma (KS), a vascular tumor linked to Kaposi sarcoma herpesvirus/human herpesvirus 8 (HHV-8), has seen increased detection during the pandemic. This study reports a case of classic cutaneous KS in a 79-year-old male following the first dose of the ChAdOx1 nCov-19 vaccine, without prior SARS-CoV-2 infection. The patient developed multiple reddish-blue papules on his legs and feet, confirmed as KS through histopathology. Treatment included radiotherapy and sequential chemotherapy with Doxorubicin. The potential reactivation of latent HHV-8 by the vaccine is explored through mechanisms involving the SARS-CoV-2 spike protein and adenovirus vector, which may induce immune responses and inflammatory pathways. Although establishing a direct causal link remains challenging, the case highlights the need for vigilance regarding KS reactivation post-vaccination. Further large-scale studies are warranted to elucidate the relationship between COVID-19 vaccines and latent virus reactivation, ensuring comprehensive safety assessments and informed public health decisions. Full article

Introduction: As the COVID-19 pandemic becomes an endemic state, still many questions remain regarding the risks and impact of SARS-CoV-2 infection and vaccination in patients with immune-mediated inflammatory diseases (IMIDs) who were excluded from the phase 3 COVID-19 vaccination trials. Methods: The BELCOMID study collected patient data and serological samples from a large, multicentric IMID patient cohort that was prospectively followed during sequential stages of the pandemic. Patients were stratified according to vaccination status into five groups across three sampling periods. Interactions between SARS-CoV-2 infection, COVID-19 vaccination status, IMID-treatment modalities and IMID course were explored. Results: In total, 2165 patients with IBD, a dermatological or rheumatological IMID participated. SARS-CoV-2 infection rates increased over the course of the pandemic and were highest in IMID patients that had refused every vaccine. After baseline COVID-19 vaccination, serologic spike (S)-antibody responses were attenuated by particular types of immune-modulating treatment: anti-TNF, rituximab, JAKi, systemic steroids, combined biologic/immunomodulator treatment. Nonetheless, S-antibody concentration increased progressively in patients who received a booster vaccination, reaching 100% seroconversion rate in patients who had received two booster vaccines. Previous SARS-CoV-2 infection was found as a predictor of higher S-antibody response. Patients who had refused every vaccine showed the lowest rates of S-seroconversion (53.8%). Multiple logistic regression did not identify previous SARS-CoV-2 infection as a risk factor for IMID flare-up. Furthermore, no increased risk of IMID flare-up was found with booster vaccination. Conclusions: Altogether, the BELCOMID study provides evidence for the efficacy and safety of COVID-19 vaccination and confirms the importance of repeated booster vaccination in IMID patients. Full article

mRNA vaccines have shown great potential in responding to emerging infectious diseases, with their efficacy and stability largely dependent on the delivery vehicles—lipid nanoparticles (LNPs). This study aims to explore the mechanisms by which LNPs encapsulate mRNA, as well as the effects of different N/P ratios and acid types in nucleic acid solutions on the structure and properties of LNPs, using the ethanol solvent injection method as the encapsulation technique. Six systems were designed, based on the composition and proportions of the existing mRNA vaccine mRNA-1273, and molecular dynamics (MD) simulations were employed to investigate the self-assembly process of LNPs. Ethanol was used as a solvent instead of pure water to better mimic experimental conditions. The results indicate that lipid components self-assemble into nanoparticles under neutral conditions, with the ionizable lipid SM-102 predominantly concentrating in the core of the particles. Upon mixing with nucleic acids in acidic conditions, LNPs undergo disassembly, during which protonated SM-102 encapsulates mRNA through electrostatic interactions, forming stable hydrogen bonds. Cluster structure analysis revealed that the four lipid components of LNPs are distributed sequentially from the outside inwards as DMG-PEG 2000, DSPC, cholesterol, and protonated SM-102. Moreover, LNPs constructed under low pH or low N/P ratios using citric acid exhibited larger volumes and more uniform distribution. These findings provide a scientific basis for further designing and optimizing LNP components to enhance the efficacy of mRNA vaccine encapsulation. Full article