Search Results (699)

Background: The long-term immune implications of administering more than four doses of COVID-19 vaccine and the impact of breakthrough infections are not fully understood. Research Design and Methods: We conducted a follow-up cohort study on Japanese healthcare workers who received more than three doses of the BNT162b2 vaccine. We assessed both the anti-SARS-CoV-2 antibody titer and cellular immunity in 429 participants and investigated the numbers, types, and brands of COVID-19 vaccines administered, as well as the episodes of COVID-19 infections after the third dose. Results: Individuals who received three total doses of vaccines with BTI episodes demonstrated higher antibody titers than those who received four total doses of vaccines with no BTIs. The cellular immune responses between these two groups were comparable. Conclusions: These findings suggest that BTIs occurring after the primary series of COVID-19 vaccinations (first to third dose) induced humoral immunity to the spike protein that is greater than that induced by booster doses (fourth or fifth dose) and elicit cellular immunity to the spike protein comparable to that of booster doses. Full article

(1) Background: The ongoing global health threat posed by SARS-CoV-2 requires reliable and accessible diagnostic tools, especially in resource-limited settings where RT-qPCR may be impractical. This study describes the development and validation of two enzyme-linked immunosorbent assays (ELISA) designed to detect anti-SARS-CoV-2 IgG antibodies employing recombinant S1 and S2 spike protein subunits. (2) Methods: The assays were optimized and validated using serum samples from 354 RT-qPCR-confirmed hospitalized patients and 337 pre-pandemic blood donors. (3) Results: The S1-based ELISA achieved a 52.8% sensitivity and a specificity of 93.5%, with an area under the ROC curve (AUC) of 71.6%. In contrast, the S2-based ELISA demonstrated superior diagnostic performance, with a sensitivity of 63.7%, a specificity of 99.7%, and an AUC of 83.1%. Cross-reactivity analysis using sera from individuals with unrelated infectious diseases confirmed the high specificity of the S2-ELISA. Time-stratified analysis revealed that sensitivity increased with time, peaking between 15 and 21 days post-symptom onset. Compared to commercial serological assays, the S2-ELISA demonstrated comparable or improved performance, particularly in specificity and diagnostic odds ratio. (4) Conclusions: The S2-ELISA offers a robust, highly specific, and operationally simple tool for serological detection of SARS-CoV-2 infection. Its strong diagnostic performance and accessibility make it well-suited for implementation in diverse epidemiological settings, particularly where molecular testing is limited. The development of affordable, validated serological assays such as this is critical for strengthening surveillance, understanding transmission dynamics, and informing public health responses. Full article

Background: Retinal vascular occlusion (RVO) and retinal artery occlusion (RAO) have been reported as rare adverse events following COVID-19 vaccination, raising concerns about vaccine safety. This review synthesizes cohort and case–control studies assessing the association between COVID-19 vaccines and RVO/RAO, while exploring potential pathophysiological mechanisms. Methods: We analyzed large-scale population-based studies from South Korea, Europe, and the TriNetX database, focusing on odds ratios (OR), hazard ratios (HR), and relative risks (RR) across mRNA and adenoviral vector vaccines. Pathological processes were hypothesized based on molecular and clinical evidence. Results: Studies investigating the association between COVID-19 vaccination and retinal vascular occlusion show conflicting results; some studies report no association (e.g., OR 0.93, 95% CI 0.60–1.45), others suggest reduced risk (e.g., OR 0.80, 95% CI 0.64–0.99), and one indicates increased risk over two years (HR 2.19, 95% CI 2.00–2.39). Adenoviral vector vaccines, particularly ChAdOx1, show higher RAO incidence in specific cohorts. Proposed mechanisms include vaccine-induced immune thrombotic thrombocytopenia (VITT) via anti-PF4 antibodies, spike protein-mediated endothelial dysfunction, and adjuvant-driven inflammation. Conclusions: While causality remains unproven, temporal heterogeneity and vaccine type-specific risks warrant further investigation. Longitudinal studies with robust controls are needed to clarify these associations in the post-pandemic context. Full article

Virus-like nanoparticles (VNPs) based on Moloney murine leukemia virus represent a well-established platform for the expression of heterologous molecules such as cytokines, cytokine receptors, peptide MHC (pMHC) and major allergens, but their application for inducing protective anti-viral immunity has remained understudied as of yet. Here, we variably fused the wildtype SARS-CoV-2 spike, its receptor-binding domain (RBD) and nucleocapsid (NC) to the minimal CD16b-GPI anchor acceptor sequence for expression on the surface of VNP. Moreover, a CD16b-GPI-anchored single-chain version of IL-12 was tested for its adjuvanticity. VNPs expressing RBD::CD16b-GPI alone or in combination with IL-12::CD16b-GPI were used to immunize BALB/c mice intramuscularly and subsequently to investigate virus-specific humoral and cellular immune responses. CD16b-GPI-anchored viral molecules and IL-12-GPI were well-expressed on HEK-293T-producer cells and purified VNPs. After the immunization of mice with VNPs, RBD-specific antibodies were only induced with RBD-expressing VNPs, but not with empty control VNPs or VNPs solely expressing IL-12. Mice immunized with RBD VNPs produced RBD-specific IgM, IgG_2a and IgG₁ after the first immunization, whereas RBD-specific IgA only appeared after a booster immunization. Protein/peptide microarray and ELISA analyses confirmed exclusive IgG reactivity with folded but not unfolded RBD and showed no specific IgG reactivity with linear RBD peptides. Notably, booster injections gradually increased long-term IgG antibody avidity as measured by ELISA. Interestingly, the final immunization with RBD–Omicron VNPs mainly enhanced preexisting RBD Wuhan Hu-1-specific antibodies. Furthermore, the induced antibodies significantly neutralized SARS-CoV-2 and specifically enhanced cellular cytotoxicity (ADCC) against RBD protein-expressing target cells. In summary, VNPs expressing viral proteins, even in the absence of adjuvants, efficiently induce functional SARS-CoV-2-specific antibodies of all three major classes, making this technology very interesting for future vaccine development and boosting strategies with low reactogenicity. 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/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: Patients suffering from inflammatory bowel diseases (IBDs) undergoing treatment with anti-TNF antibodies mount a diminished humoral immune response to vaccination against SARS-CoV-2 compared to healthy controls. The characterization of variant-specific immune responses is particularly warranted among immunosuppressed patients, where reduced responses may necessitate further medical interventions. Methods: This pilot study investigated the humoral immune response of vaccinated IBD patients on anti-TNF medication and a comparable group of healthy individuals against the viral variants Alpha, Beta, Gamma, Delta, and Omicron BA.1 and BA.5. While total IgG antibodies targeting the receptor binding site of the spike protein of SARS-CoV-2 were quantified using a chemiluminescence microparticle immunoassay (CMIA), their potential neutralizing capacity was determined using commercial and variant-specific in-house surrogate virus neutralization tests (sVNTs) against a variant-specific in-house VSV-pseudotyped virus neutralization test (pVNT) as the gold standard. Results: Employing variant-specific assays recapitulated the immune escape functions of virus variants. Conspicuously, antibody reactivity against Alpha and Omicron BA.1 and BA.5 was strikingly poor in IBD patient sera post-initial vaccination compared to healthy individuals. A comparison of the diagnostic performance of assays with the pVNT revealed that identification of patients with inadequate humoral responses by CMIA and sVNT may require adjustments to cut-off values and end-point titration of sera. Following adaptation of cut-off values, patient sera exhibited reduced reactivity against all tested variants. The assay panel used substantiated the impact of anti-TNF therapy in IBD patients as to reduced strength, function, and breadth of the immune response to several SARS-CoV-2 variants. The immune response measured following the second vaccination was comparable to the antibody response observed in healthy individuals following the first vaccination. Conclusion: Variant-specific sVNTs and pVNTs have the potential to serve as valuable tools for evaluating the efficacy of adapted vaccines and to inform clinical interventions in the care of immunosuppressed patients. Anti-TNF-treated individuals with antibody levels below the optimized CMIA threshold should be considered for early booster vaccination and/or close immunological monitoring. 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: Severe acute respiratory syndrome (SARS-CoV-2) has had a profound global impact and continues to represent a health challenge worldwide. The durability of SARS-CoV-2 vaccine responses in pediatric inflammatory bowel disease (PIBD) patients receiving biologic therapies is unknown. This study aimed to quantify SARS-CoV-2 antibody responses post vaccination in these immunosuppressed patients over 12 months. Methods: Prospective study comparing antibody responses against SARS-CoV-2 spike protein at 1, 3, 6, and 12 months in PIBD patients aged 5–18 years treated with anti-tumor necrosis factor alpha (anti-TNF) therapies with or without an immunomodulator (IM) versus vedolizumab. Results: Between 1 May 2021 and 1 May 2022, 194 participants on anti-TNF monotherapy (n = 78), anti-TNF with IM (n = 83), vedolizumab (n = 15), and steroids (n = 18) were recruited. Anti-SARS-CoV-2 spike levels increased after the first vaccine and were further boosted 1 month after the second dose. Linear mixed-effects modelling showed antibody waning over time (effect difference −2509 IgG AU/mL per week [95%CI: −4998–−20, p = 0.048]), counterbalanced by booster doses (effect difference 184,138 IgG AU/mL per additional vaccine dose [95%CI: 138,342–229,934, p < 0.001]). Receiving anti-TNF therapy contributed to reduced antibody responses compared to vedolizumab (anti-TNF monotherapy effect difference: −212,640 [95%CI: −336,928–−88,351] p = 0.001; anti-TNF with IM: −151,880 [95%CI: −277,309–−26,451] p = 0.018). Seroconversion and breakthrough infection rates were similar between groups, and all infections were mild, without hospitalizations. Conclusions: Although SARS-CoV-2 antibody responses were attenuated in PIBD patients receiving anti-TNF therapy compared with vedolizumab, this did not impact protection, as seroconversion and breakthrough infection rates were similar, with no hospitalizations. These data reinforce the importance of updating vaccines and, in particular, SARS-CoV-2 vaccines in immunosuppressed PIBD patients on advanced therapies. Full article

Circulating tumor cell enrichment and enumeration are advancing early detection of cancer, monitoring of therapy response, and even next-generation therapies. Efficiently capturing rare cells from complex biological fluids is essential in both diagnostic and therapeutic applications. EpCAM-positive tumor cells are specifically captured by utilizing covalently immobilized anti-EpCAM monoclonal antibodies onto the surface of chemically modified glass microbeads. To maximize the capture efficiency, bead geometry, immobilization conditions, flow rate, and anticoagulant dosage were systematically optimized. An in vitro flow-capture system was designed and used to evaluate the capture efficiency of the proposed technology by utilizing HTC116 colon cancer cell-spiked model media. The effect of substrate surface pretreatment was characterized by goniometry, while the capture performance was monitored by flow cytometry and fluorescent microscopy. The specific capture ability of the bioactive microbead substrate reached over 130,000 cells in the laboratory-scale cartridge (V(cartridge) = 2.6 cm³; m(bead) = 4 g). This capture efficiency suggests a promising rare-cell capture utilization of the proposed technology and may be used for research, diagnostic, and therapeutic purposes. In this paper, we reported on the development and feasibility test of a high-performance bioactive glass-microbead cell capture substrate. Due to the relevance and novelty of the reported results, with further development, the versatile platform technology presented could be readily implemented to capture tumor cells from complex biological samples and represent an additional complementary tool to existing cancer diagnostics and therapies. Full article

Background: The 2019 coronavirus disease (COVID-19) pandemic had a severe impact on frail, end-stage kidney disease (ESKD) patients, either on dialysis or transplanted, with a high mortality rate in the early waves. Vaccination against SARS-CoV-2 with mRNA vaccines has led to reduced hospitalization and mortality rates in the general population and ESKD patients. Neutralizing antibodies (NAbs) are a valuable correlate of protection after vaccination, and IgG anti-spike antibodies are considered a surrogate marker of protection. Methods: This study investigated the correlates of protection brought by NAb and anti-spike IgG antibodies against SARS-CoV-2 wild-type Wuhan strain and variants of concern in a cohort of 128 French patients on dialysis after vaccination with the BNT162b2 mRNA vaccine. The correlate was assessed using Receiver Operating Characteristic curves. Results: The level of protection for IgG anti-spike antibodies was set at 917 BAU/mL for the original Wuhan strain and 980 BAU/mL and 1450 BAU/mL, respectively, for the Delta and Omicron BA.1 variants. Conclusions: The level of protection can be regularly monitored by measuring IgG anti-spike antibody concentrations to allow tailored boosters of SARS-CoV-2 vaccination in this frail and immunocompromised ESKD population. Full article

The SARS-CoV-2 virus poses a significant risk to immunocompromised patients, who display weakened immunity and reduced seroconversion following infection and vaccination. In this study, we recruited 19 hospitalized patients with immune disorders (ImCo) and 4 immunocompetent controls (ICC) with COVID-19. We evaluated their serological, humoral, and cellular immune responses at <30 days and >90 days post-symptom onset. ICC patients showed robust B and T cell responses against SARS-CoV-2, indicated by detectable antibody levels, memory antibody-secreting cells (mASCs) towards the spike protein and spike-specific CD4⁺ and CD8⁺ T cells. ImCo patients showed impaired immune responses, with lower levels of B cell responses. Further subdivision of the ImCo patients demonstrates that solid organ transplant (SOT) patients generated B cell responses similar to ICC patients, whereas the other ImCo patients, including patients with hematological malignancies and anti-CD20 therapy, did not. Absolute T cell numbers and spike-specific CD4⁺ and CD8⁺ T cell responses were low in the ImCo patients at <30 days but increased at later time points. Our findings suggest that even when B cell responses were reduced, patients could present a T cell response, suggesting a more successful line of passive immunization for immunocompromised individuals focusing on boosting T cell responses. Full article

mRNA vaccines have demonstrated considerable efficacy and safety against SARS-CoV-2, limiting the pandemic burden worldwide. The emergence of new variants of concern and the decline in neutralizing activity observed several weeks post-vaccination reinforced the call for repeated mRNA vaccination. We and others have shown that vaccine efficacy does not exclusively rely on antibody neutralizing activites; Fc-effector functions play an important role as well. However, it is well known that long-term exposure and repeated antigen stimulation elicit the IgG4 subclass of antibodies, which are inefficient at mediating Fc-effector functions. In this regard, recent studies highlighted concerns about IgG4 induction by mRNA vaccines. Here, we explored the impact of repeated mRNA vaccination on IgG4 induction and its impact on Fc-effector functions. We observed anti-Spike IgG4 elicitation after three doses of mRNA vaccine; the antibody levels further increased with additional doses. Vaccine-elicited IgG4 preferentially bound the ancestral D614G Spike. We also observed that Breakthrough Infection (BTI) after several doses of vaccine strongly increased IgG1 levels but had no impact on IgG4 levels, thereby improving Fc-effector functions. Finally, we observed that elderly donors vaccinated with Moderna mRNA vaccines elicited higher IgG4 levels and presented lower Fc-effector functions than donors vaccinated with the Pfizer mRNA vaccine. Altogether, our results highlight the importance of monitoring the IgG subclasses elicited by vaccination. Full article

SARS-CoV-2 has caused global disruptions, prompting studies on immune responses to COVID-19 vaccines, particularly antibodies against the Spike (S) protein. However, responses to the Nucleocapsid (N) protein remain less explored. This study evaluated whether CoronaVac induces anti-N antibodies, and analyzed antibody dynamics after a BNT162b2 booster, given that CoronaVac targets both S and N proteins, while BNT162b2 targets only the S protein. Serum samples were collected at multiple intervals post-vaccination. The percentage of participants with positive anti-N antibodies increased from 40.26% to 62.09% after two doses of CoronaVac, but declined over time, reaching 29.07% and 18.87% after the second and third doses, respectively. However, seropositivity rose to 43.48% three months after the booster. Anti-S antibody levels peaked at 31,394 AU/mL after the booster, compared to 723.4 AU/mL after the first dose. These findings indicate that CoronaVac stimulates antibody responses against both S and N proteins. Monitoring antibody dynamics is crucial for optimizing vaccination strategies, particularly for high-risk populations, to help control COVID-19. Full article