Search Results (339)

COVID affects around 400 million individuals today with a strong economic impact on the global economy. The list of long COVID symptoms is extremely broad because it is derived from neurological, cardiovascular, respiratory, immune, and renal dysfunctions and damages. We review here these pathophysiological manifestations and the predictors of this multi-organ pathology like the persistence of the virus, altered endothelial function, unrepaired tissue damage, immune dysregulation, and gut dysbiosis. We also discuss the similarities between long COVID and vaccine side effects together with possible common immuno-inflammatory pathways. Since the spike protein is present in SARS-CoV-2 (and its variants) but also produced by the COVID vaccines, its toxicity may also apply to all mRNA or adenoviral DNA vaccines as they are based on the production of a very similar spike protein to the virus. After COVID infection or vaccination, the spike protein can last for months in the body and may interact with ACE2 receptors and mannan-binding lectin (MBL)/mannan-binding lectin serine protease 2 (MASP-2), which are present almost everywhere in the organism. As a result, the spike protein may be able to trigger inflammation in a lot of organs and systems similar to COVID infection. We suggest that three immuno-inflammatory pathways are particularly key and responsible for long COVID and COVID vaccine side effects, as it has been shown for COVID, which may explain in large part their strong similarities: the renin–angiotensin–aldosterone system (RAAS), the kininogen–kinin–kallikrein system (KKS), and the lectin complement pathway. We propose that therapeutic studies should focus on these pathways to propose better cures for both long COVID as well as for COVID vaccine side effects. Full article

mRNA-LNP-based COVID-19 vaccines, namely Pfizer-BioNTech’s Comirnaty and Moderna’s Spikevax, were successfully deployed to help control the SARS-CoV-2 pandemic, and their updated formulations continue to be recommended, albeit only for high-risk populations. One widely discussed aspect of these vaccines is their uniquely broad spectrum and increased incidence of adverse events (AEs), collectively referred to as post-vaccination syndrome (PVS). Although the reported PVS rate is low, the high number of administered doses among healthy individuals has resulted in a substantial number of reported vaccine-related injuries. A prominent manifestation of PVS is multisystem inflammation, hypothesized to result from the systemic transfection of organ cells with genetic instructions for a toxin, the spike protein, delivered with lipid nanoparticles (LNPs). In this narrative review, we focus on endothelial cells in the microcirculatory networks of various organs as primary sites of transfection with mRNA-LNP and consequent PVS. We outline the anatomical variations in the microcirculation contributing to the individual variability of symptoms and examine the molecular and cellular responses to vaccine nanoparticle exposure at the endothelial cell level with a focus on the pathways of a sustained cascade of toxic and autoimmune processes. A deeper understanding of the mechanisms underlying mRNA-LNP-induced AEs and PVS at the organ and cellular levels is critical for improving the safety of future vaccines and other therapeutic applications of this groundbreaking technology. Full article

Background/Objectives: mRNA vaccines introduced during the COVID-19 pandemic were a significant step forward in the rapid development and deployment of vaccines in a global pandemic context. These vaccines showed good protective efficacy, but—due to limited breadth of the immune response—they required frequent boosters with manufactured spike sequences that often lagged behind the circulating strains. In order to enhance the breadth, durability, and magnitude of immune responses, we studied the effect of combining priming with an RNA vaccine technology with boosting with protein/adjuvant using a TLR4-agonist based adjuvant. Methods: Specifically, four proprietary adjuvants (EmT4^TM, LiT4Q^TM, MiT4^TM, and AlT4^TM) were investigated in combination with multiple modes of SARS-CoV-2 vaccination (protein, peptide, RNA) for their effectiveness in boosting antibody responses to SARS-CoV-2 spike protein in murine models. Results: Results showed significant improvement in immune response strength and breadth—especially against more distant SARS-CoV-2 variants such as Omicron—when adjuvants were used in combination with boosters following an RNA vaccine prime. Conclusions: The use of novel TLR4 adjuvants in combination with protein or RNA vaccinations presents a promising strategy for improving the efficacy of vaccines in the event of future pandemics, by leveraging rapid response using an RNA vaccine prime and following up with protein/adjuvant-based vaccines to enhance the breadth of immunity. Full article

The emergence of a novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus closely related to SARS-CoV and officially known as Betacoronavirus pandemicum precipitated a substantial surge in vaccine development that culminated during the global COVID-19 pandemic. At present, there are dozens of vaccines for the prevention of SARS-CoV-2 being utilized across the globe. However, only 10 of these vaccines have been authorized by the World Health Organization (WHO). These include mRNA-based, viral vector, subunit and whole-virion inactivated vaccines. At the current end of the pandemic, there has been a decline in the global vaccination rate, both for the general population and for those most at risk of severe illness from the virus. This suggests that the effectiveness of the vaccines may be waning. The decline occurs alongside a decrease in testing and sequencing for SARS-CoV-2. Furthermore, the process of tracking viruses becomes increasingly complex, thereby providing a selective advantage for SARS-CoV-2 and allowing it to evolve stealthily. In this review, we provide a comprehensive overview of viral evolution and vaccine development. We also discuss ways to overcome viral variability and test universal vaccines for all SARS-CoV-2 variants. Full article

Patients undergoing peritoneal dialysis (PD) represent a uniquely vulnerable population due to intrinsic immunological dysfunction and a high prevalence of comorbid conditions. This review examines the complex interplay between natural and vaccine-induced immune responses to SARS-CoV-2 in this group, focusing on viral entry, immune activation, and immune evasion mechanisms. Particular attention is given to the impaired cellular and humoral responses seen in PD patients, including reduced T-cell function, diminished antibody production, and abnormal cytokine signaling, all of which contribute to an elevated risk of severe COVID-19 outcomes. The immunogenicity and clinical efficacy of various vaccine platforms, including inactivated, vector-based, and mRNA formulations, are critically assessed, with an emphasis on the role of booster doses in enhancing protection amid waning immunity and evolving viral variants. Furthermore, the review highlights the advantages of PD as a home-based modality that is compatible with telemedicine and may reduce the risk of viral exposure. These insights underscore the importance of developing individualized vaccination strategies, maintaining close immunological surveillance, and implementing innovative dialysis care approaches to improve clinical outcomes during the ongoing pandemic and future public health crises. Tailored booster strategies and telemedicine-integrated care models are essential for improving outcomes in this high-risk population. Full article

Background and objective: The approval of mRNA-based vaccines for children and adolescents has contributed to global efforts to control the SARS-CoV-2 pandemic. While hybrid immunity—combining prior SARS-CoV-2 infection and vaccination—may offer enhanced protection, data on its effectiveness versus vaccine-induced immunity in the pediatric population are limited. Methods: This retrospective matched cohort study used linked health data from Norwegian nationwide health registries and the Italian Pedianet network. The study included children and adolescents aged 5–14 years eligible for COVID-19 vaccination at the time of approval (May/September 2021 and November 2021/January 2022, respectively). Mono- and two-dose vaccination schedules were assessed, and hybrid immunity was defined as prior SARS-CoV-2 infection followed by vaccination within 12 months. Conditional Cox regression models were used to estimate hazard ratios (HRs) for SARS-CoV-2 infection risk, adjusting for sociodemographics, comorbidities, and healthcare utilization. Results: The study included 626,537 children and adolescents in Norway and 38,938 in Italy. A single dose of the vaccine did not reduce the risk of infection among SARS-CoV-2–naive individuals in Norway (HR: 1.05; 95% CI: 1.04–1.07), whereas it was associated with an 8% risk reduction in Italy (HR: 0.92; 95% CI: 0.88–0.96). Among individuals with a recent prior infection (within 12 months), vaccination was associated with a reduced risk of reinfection in Norway (HR: 0.10; 95% CI: 0.05–0.13), but not in Italy (HR: 1.22; 95% CI: 0.83–1.80), compared to no vaccination. Among those with prior infection, vaccination was associated with a significantly reduced risk of reinfection in Norway (HR = 0.10; 95% CI: 0.05–0.20), but not in Italy (HR = 0.55; 95% CI: 0.27–1.11). Hybrid immunity provided greater protection against (re-)infection compared to vaccine-induced immunity alone, with a 26% risk reduction observed in Norway (HR = 0.74; 95% CI = 0.47–0.1.16) and an 86% reduction in Italy (HR = 0.14; 95% CI = 0.09–0.21). Conclusions: This analysis supports the effectiveness of SARS-CoV-2 vaccines in children, with hybrid immunity offering enhanced protection against reinfection. Given the waning effectiveness of vaccines over time, continued research and booster strategies are essential to sustain protection and mitigate transmission. Full article

Background/Objectives: The SARS-CoV-2 pandemic challenged patients with inflammatory bowel disease (IBD) under immunosuppressive therapies. We used data from the RisCoin cohort to investigate factors associated with a poor immune response to mRNA vaccination in these patients. Methods: From 4115 RisCoin participants, we matched 110 IBD patients by age and time interval since the second mRNA vaccination with 306 healthcare workers (HCW) without comorbidities (HCW-healthy) and 292 with medical conditions (HCW-plus); all were SARS-CoV-2 infection naïve. Basic questionnaires collected data on medication, COVID-19 vaccinations and side-effects, dietary patterns, lifestyle factors, and self-perceived stress. Main outcomes included anti-spike immunoglobulin levels and antibody-mediated live-virus neutralization immunity (NT) to the Omicron BA.1 variant (threshold NT ≥ 10 defined as IC50 values ≥1:10 serum dilution) after the second (baseline) and third vaccinations. Results: At baseline, IBD patients treated with anti-TNF but not those under vedolizumab or ustekinumab therapy had lower anti-spike levels compared to HCW-healthy and HCW-plus (166 versus 1384 and 1258 BAU/mL, respectively; p < 0.0001). Anti-TNF compared to vedolizumab/ustekinumab-treated patients reached NT titers above threshold in 17% versus 64%, respectively, and HCW-subgroups in 73% and 79% (all p < 0.0001). Current smokers showed a four to five times increased risk for non-neutralizing immunity compared to non-smokers. After the third vaccination, NT titers did not reach threshold in 15% anti-TNF compared to 5% vedolizumab/ustekinumab-treated patients and none of HCW (p < 0.01). Patients with IBD reported fewer clinical symptoms after vaccination. Perceived stress was not increased. Conclusions: Our findings support individualized schedules for mRNA-based vaccines in IBD patients with different immunosuppressive therapies and enforcement of non-smoking. Full article

Vaccine-induced thrombotic thrombocytopenia (VITT) is a rare thrombotic disorder first identified in 2021 as a catastrophic syndrome associated with anti-SARS-CoV-2 adenoviral vector (AdV)-vaccine administration. It is characterized by the presence of oligo- or monoclonal anti-PF4 antibodies able to induce in vitro platelet activation in the presence of PF4. In addition to this immune-based pathomechanism, random splicing events of the Adv-vector DNA encoding for SARS-CoV-2 spike protein resulting in the secretion of soluble spike variants have been postulated as a possible pathophysiological mechanism. More recently, some novel clinical-pathological anti-PF4-associated entities also characterized by thrombosis, thrombocytopenia, and VITT-like antibodies but independent from heparin or AdV-vaccine administration have been identified. To date, these VITT-like disorders have been reported following the administration of vaccines different from anti-SARS-CoV-2 AdV-vaccines, like human papillomavirus (HPV) and mRNA-based COVID-19 vaccines, following a bacterial or viral respiratory infection, and in patients with a monoclonal gammopathy of undetermined significance. The purpose of this review is to provide an update on the knowledge on VITT pathogenesis, focusing on recent findings on anti-PF4 antibodies, on a possible genetic predisposition to VITT, on VITT-antibody intracellular activated pathways, on lipid metabolism alterations, and on new VITT-like disorders. Full article

Background: SARS-CoV-2 immunity is understudied in cancer patients. Here, we monitored natural/vaccine-induced SARS-CoV-2 immunity in patients with head and neck cancer (HNC) stratified as vaccinated (mRNA/adenovirus-based vaccines), convalescent, and hybrid immunity. Methods: Plasma/PBMC samples were collected from 49 patients with HNC and 14 non-oncologic controls recruited between August 2021 and March 2022. Longitudinal follow-up was performed on 25 HNC patients. Plasma antibodies (Abs) against Spike (S1/S2), receptor-binding domain (RBD), and nucleocapsid (NC) of IgG/IgA isotypes and 25 cytokines/chemokines were quantified using MILLIPLEX^® technology. The frequency, phenotype, and isotype of circulating SARS-CoV-2-specific B-cells were studied by flow cytometry using RBD tetramers (Tet⁺⁺). The proliferation of B-cells and CD4+ and CD8+ T-cells in response to Spike/NC peptides was monitored by a carboxyfluorescein succinimidyl ester (CFSE) assay. Results: Plasma SARS-CoV-2 S1/S2/RBD IgG/IgA Abs were detected in all HNC participants at enrollment median time since immunization (TSI) 117 days at levels similar to controls and were significantly higher in convalescent/hybrid versus vaccinated. NC IgG/IgA Abs were only detected after infection. The frequency of Tet++ B-cells, enriched in the CD27+ memory phenotype and IgG/IgA isotype, positively correlated with plasma levels of RBD IgG/IgA Abs and Spike-specific CD4+ T-cell proliferation, regardless of the immunization status and TSI. Spike/NC-specific B-cell proliferation reached the highest levels in convalescent HNC and was positively correlated with NC IgG Abs, but not with the frequency of Tet++ B-cells. Finally, Tet++ B-cell frequencies remained stable between the two subsequent visits (median TSI: 117 versus 341 days), indicating their ability to persist for a relatively long time. Conclusions: This study monitored SARS-CoV-2 humoral/cellular immunity in an HNC cohort relative to non-oncologic participants and demonstrates that SARS-CoV-2-specific B-cells persist beyond 11 months post-immunization. These findings have implications for the management of HNC in the context of SARS-CoV-2 infection and other viral infections. Full article

Background: Increasing evidence suggests that the immunogenicity of COVID-19 mRNA vaccines might influence the efficacy of immune checkpoint inhibitors (ICIs). Current studies have not considered the impact of additional vaccinations, which are now recommended as a preventive strategy against SARS-CoV-2 infection for cancer patients receiving active treatments. Consequently, we leveraged the prospective monitoring from the Vax-On-Third study to explore whether periodic mRNA vaccine boosters administered around the start of ICIs could influence the rates of immune-related adverse events (irAEs) and survival outcomes in patients with advanced non-small cell lung cancer (NSCLC). Methods: Our study included patients with a histological diagnosis of metastatic NSCLC and available PD-L1 tumor proportion score (TPS), who had undergone at least two cycles of upfront treatment with pembrolizumab, cemiplimab, or their combination with platinum-based chemotherapy. Patients who received any additional mRNA-based vaccine doses within 60 days before to 30 days after starting ICIs accounted for the exposed cohort. Those who declined further boosters formed the reference cohort. We analyzed differences in irAE frequencies, progression-free survival (PFS), and overall survival (OS) using univariate and multivariate analyses. Results: Between 27 November 2021 and 31 March 2024, we enrolled 226 eligible patients. The exposed cohort consisted of 112 patients who had received either a third or fourth dose of tozinameran or a bivalent booster. Based on PD-L1 expression levels, 93 (41%) and 133 (59%) patients received single-agent ICIs (PD-L1 TPS ≥ 50%) or combination regimens (PD-L1 TPS < 50%), respectively. Propensity-score matching using comprehensive criteria resulted in two cohorts of 102 patients each, with an optimal balance of prognostic factors. A thorough analysis of any grade irAEs showed no significant differences between the cohorts. A longitudinal survival assessment with a median follow-up of 22.8 (95% CI 19.2–26.0) months showed no difference between the cohorts. The median PFS for the reference and exposed cohorts was 7.5 (95% CI 5.9–9.1) and 8.2 (95% CI 6.2–10.2) months, respectively (p = 0.408; HR 0.88 [95% CI 0.66–1.18]). The median OS for the reference and exposed cohorts was 10.5 (95% CI 7.9–13.0) and 13.8 (95% CI 12.0–15.5) months, respectively (p = 0.170; HR 0.81 [95% CI 0.59–1.09]). Multivariate analysis confirmed that receiving additional mRNA vaccine boosters did not significantly affect the risk of disease progression or mortality. Univariate analysis within the subgroup of patients with high PD-L1 TPS who received single-agent ICIs showed a significant OS advantage for patients in the exposed cohort (9.7 [95% CI 8.1–11.2] vs. 18.6 [95% CI 13.5–23.6] months; p = 0.034; HR 0.59 [95% CI 0.36–0.96]). Conclusion: After optimally balancing prognostic factors, regular mRNA vaccine boosters at the onset of ICIs did not impact the safety and survival of patients with advanced NSCLC. The improved outcome observed in patients with high PD-L1 expression levels aligns with previous findings and warrants further investigation. Full article

Background/Objectives: This study examines the longitudinal dynamics of anti-nucleocapsid (anti-N) and anti-spike (anti-S) antibody responses to SARS-CoV-2 infection and mRNA vaccination based on 81,878 serum samples from 23,616 healthcare workers (HCWs) across five European countries. It includes data across four scheduled vaccine doses—predominantly BNT162b2—with 25% of samples originating from individuals with confirmed prior infection, as evidenced by elevated anti-S levels, positive Anti-N antibodies, or PCR results. Methods: The study employed a shifted transformation method for data normalization and utilized the Bass diffusion model to predict antibody titer dynamics influenced by both internal factors—such as immune activation contextualized through sociodemographic issues—and external factors, including infection and vaccination. Despite the absence of direct measurements for some internal variables, the model effectively inferred their impact, enabling a rigorous and nuanced delineation of immune response profiles. Results: The Bass diffusion model rigorously captured variations in antibody titers, analyzed through demographic factors such as gender, age, and job role, while thoroughly accounting for pre-infection status. The results indicate that Anti-N antibodies, exclusively produced post-infection, exhibited a rapid decline, while anti-S antibodies, generated from both infection and vaccination, demonstrated prolonged persistence. A significant decline in anti-S levels was observed 3–5 months post-vaccination, with adaptive immunity—characterized by the dominance of internal factors effects relative to external ones—achieved in most groups after the fourth dose. However, adaptive immunity post second dose was limited to specific demographics. Conclusions: These findings emphasize the significance of the Bass Method in predicting vaccine-induced, hybrid immune responses and detecting adaptive immunity by overcoming limitations in internal factor data, thereby advancing effective vaccination and infection control strategies during public health crises. These findings highlight the Bass Method’s value in predicting vaccine-induced and hybrid immunity, effectively addressing internal factor data gaps to enhance vaccination and infection control strategies. Full article

Background/Objectives: To evaluate how immune responses compare among ethnic groups approximately 2 years after receiving a third dose of COVID-19 vaccine (BNT162b2, mRNA-1273, ChAdOx1or BBIBP-CorV), we tested T cell responses and Spike-specific RBD-antibody titer, and neutralized antibody titer levels utilizing Spectral Flow cytometry, ELISA, and SARS-CoV-2 pseudotyped-based neutralization assays, respectively. Methods: Forty-four individuals from January–December 2023 were identified within the cohort and were classified into different ethnic backgrounds; Black (N = 13), Asian (N = 14), Caucasian (N = 17). We recognize that the “Asian” group includes diverse subpopulations with distinct genetic and environmental backgrounds, which could not be further stratified due to sample-size limitations. Spike-specific AIM+, CD4+, and CD8+ T cell responses were assessed and evaluated against SARS-CoV-2 variants, including the ancestral Wuhan, Delta, and multiple Omicron subvariants (B1.1529, BA2.86, BA.4/5, and XBB.1). Alongside we tested the RBD-IgG and neutralizing antibody titers against the ancestral Wuhan. Spearman’s correlation analysis was utilized to determine corelative relationships among the AIM+ and CD4+ T cell responses, as well as the RBD-IgG and neutralizing antibody titers. Results: Our results show robust and comparable RBD-IgG and neutralizing antibody titers across all groups, with a significant positive correlation between these two measurements. Significant differences were observed in T-cell activation, with Asian participants exhibiting lower frequencies of Spike-specific CD4+ T cells against SARS-CoV-2 Omicron subvariants and higher frequencies of cytokine-producing CD4+ T cells (TNF-α, IFN-γ, and IL-2) as compared to the Caucasian group. Breakthrough infection status was not fully controlled and may influence these findings. Conclusion: Despite a small sample size and potential confounding by natural infections within our long-time-span sampling, our data suggest persistent cellular and humoral immunity 2 years after vaccination across ethnicities, with notable differences in T cell activation and cytokine profile. These preliminary observations highlight the need for larger, more detailed studies that consider intra-ethnic diversity and hybrid immunity to better understand ethnic differences in COVID-19 vaccine responses. Full article

The emergence of complex and rapidly evolving pathogens necessitates innovative vaccine platforms that move beyond traditional methods. This review explores the transformative potential of next-generation vaccine technologies, focusing on the combined use of synthetic biology, nanotechnology, and systems immunology. Synthetic biology provides modular tools for designing antigenic components with improved immunogenicity, as seen in mRNA, DNA, and peptide-based platforms featuring codon optimization and self-amplifying constructs. At the same time, nanotechnology enables precise antigen delivery and controlled immune activation through engineered nanoparticles such as lipid-based carriers, virus-like particles, and polymeric systems to improve stability, targeting, and dose efficiency. Systems immunology aids these advancements by analyzing immune responses through multi-omics data and computational modeling, which assists in antigen selection, immune profiling, and adjuvant optimization. This approach enhances both humoral and cellular immunity, solving challenges like antigen presentation, response durability, and vaccine personalization. Case studies on SARS-CoV-2, Epstein–Barr virus, and Mycobacterium tuberculosis highlight the practical application of these platforms. Despite promising progress, challenges include scalability, safety evaluation, and ethical concerns with data-driven vaccine designs. Ongoing interdisciplinary collaboration is crucial to fully develop these technologies for strong, adaptable, globally accessible vaccines. This review emphasizes next-generation vaccines as foundational for future immunoprophylaxis, especially against emerging infectious diseases and cancer immunotherapy. Full article

Background: Kidney transplant (KTx) recipients exhibit impaired responses to SARS-CoV-2 vaccination. Correlates of vaccine-induced immunity and risk factors for breakthrough infection are not fully defined. This study evaluated the humoral response trajectories and determinants of breakthrough infection in KTx recipients. Methods: KTx recipients received two doses of the BNT162b2 mRNA vaccine three weeks apart and a booster after six months. Patients were categorized based on pre-vaccination status: previous COVID-19 disease (DIS), asymptomatic SARS-CoV-2 infection (INF), or infection-naïve (NEG). Serum anti-spike antibody titers were assessed at baseline, before the second dose, and at 1, 3, 6, 9, and 12 months. Linear mixed models and survival analyses were performed. Results: Of 326 enrolled patients, 189 with complete time-point data were included in the longitudinal analysis. Antibodies were detectable in 89% of DIS/INF at baseline and 91% before the second dose, but were negligible in NEG. In NEG, the seropositivity increased after vaccination and booster, reaching 78% at 12 months. Age (−5% per year, p < 0.001) and BMI (+10% per unit, p = 0.004) influenced titers; antimetabolites and steroids had strong negative effects (−70%, p = 0.005; −84%, p = 0.001). Breakthrough infections occurred in 104 (31.9%); 40% were asymptomatic, and 2 patients died. An mTOR inhibitor was associated with a reduced infection risk (OR 0.27 [CI: 0.09–0.70], p = 0.009). Higher antibody titers correlated with delayed infection (p = 0.063). Conclusions: In KTx patients, humoral response to SARS-CoV-2 vaccination is limited in infection-naïve patients but improved by booster dosing; the hybrid immunity is more effective. Immunosuppressive regimens influence the immune response, and mTOR inhibitors may protect against breakthrough infection. Full article

Background/Objectives: The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus type-2 (SARS-CoV-2), has resulted in 777 million cases worldwide. Various vaccines have been approved to control the spread of COVID-19, with mRNA vaccines (Pfizer and Moderna) being widely used in the USA. We conducted a prospective longitudinal study to analyze the immune response elicited by two/three and four doses of monovalent mRNA vaccines in both vaccinated individuals and those who experienced breakthrough infections. Participants were stratified into different age groups: 18–40, 41–60, and over 60 years. Methods: We assessed cross-variant neutralization responses in two cohorts—Cohort I: n = 167 (serum), Cohort II: n = 92 (serum and nasal swab) samples—using infectious virus microneutralization assay (MN) and antibody (IgG or IgA) binding ELISA titers to the spike protein receptor binding domain (RBD). Samples were collected from the Louisville Metro–Jefferson County Co-Immunity Project, a federally funded, population-based study for the surveillance of SARS-CoV-2 in Jefferson County, Kentucky during 2020–2022, involving both health care workers and a local community. Results: Individuals who received two doses of the mRNA vaccine exhibited reduced neutralization against Beta, Delta, and Omicron BA.1 variants compared to wildtype Wuhan, with further decline observed six months post-booster vaccination. However, individuals who experienced natural COVID-19 infection (breakthrough) after receiving two vaccine doses showed enhanced neutralization and antibody responses, particularly against Omicron BA.1. Following the 3rd dose, antibodies and neutralization responses were restored. Among triple-vaccinated individuals, reduced neutralization was observed against Omicron variants BA.1, BA.5, and BA.2 compared to Wuhan. Neutralization responses were better against BA.2 variant compared to BA.1 and BA.5. However, individuals who received three doses of vaccine and experienced a breakthrough infection (n = 45) elicited significantly higher neutralizing antibodies responses against all Omicron subvariants compared to vaccinated individuals. Interestingly, nasal swab samples collected from volunteers with breakthrough infection showed significantly elevated spike-reactive mucosal IgA antibodies and enhanced cross neutralization against BA.1, BA.2, and BA.5 compared to individuals who received only three vaccine doses. Conclusions: mRNA vaccination elicits a strong systemic immune response by boosting serum neutralizing antibodies (NAb), although this protection wanes over time, allowing new variants to escape neutralization. Breakthrough individuals have extra enrichment in nasal NAb offering protection against emerging variants. This longitudinal immune profiling underscores the strengthening of pandemic preparedness and supports the development of durable mucosal vaccines against respiratory infectious disease. Full article