Vaccines

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18 pages, 275 KB

Open AccessArticle

Humoral and Cellular Immune Response in Patients with Hematological Disorders After Three Doses of mRNA COVID-19 Vaccine: A Single-Center Observational Study

by Rosa Daffini, Francesco Zecchini, Giulia Venneri, Michele Malagola, Chiara Cattaneo, Stefano Calza, Arnaldo Caruso, Alessandra Tucci and Cinzia Giagulli

Vaccines 2026, 14(5), 369; https://doi.org/10.3390/vaccines14050369 - 22 Apr 2026

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Abstract

Background: Hematological patients have a high risk of developing severe COVID-19 (37%). Most mRNA vaccine trials in hematological patients showed a low immunogenicity after two doses, while long-term data are scarce. Methods: In this monocentric retrospective observational study, we evaluated humoral and T [...] Read more.

Background: Hematological patients have a high risk of developing severe COVID-19 (37%). Most mRNA vaccine trials in hematological patients showed a low immunogenicity after two doses, while long-term data are scarce. Methods: In this monocentric retrospective observational study, we evaluated humoral and T cell-mediated immune responses in 230 hematological patients after three doses of the Pfizer-BioNTech mRNA COVID-19 vaccine. Patients were stratified by age, disease type/state, prior COVID-19 infection, and treatment status and regimens (anti-CD20 monoclonal antibodies, BTK and BCL-2 inhibitors, and treatment line). Antibody titer to SARS-CoV-2 was assessed by electrochemiluminescence immunoassay and T cell response by QuantiFERON interferon-γ release assay (IGRA). Data were analyzed using univariate (Fisher’s exact test) and Firth’s bias-reduced penalized-likelihood logistic regression. Results: A robust humoral response was observed with 91.55% of patients developing anti-spike antibodies (GMT 988.83 U/mL). Anti-CD20-bendamustine treatment was associated with a significantly lower antibody positivity compared to untreated subjects. Prior COVID-19 infection significantly boosted both antibody positivity (95.9% vs. 85.2%) and GMT (847.02 U/mL vs. 258.79 U/mL). Conversely, T cell response was suboptimal (36.1% positive), particularly in anti-CD20-bendamustine-treated and multi-treated patients (27.1%), but highest in those treated with BTK inhibitors (50%). Multivariable logistic regression analysis linked multiple treatments to lower T cell response. Following vaccination, 29.1% of patients contracted SARS-CoV-2, but only 0.89% developed severe COVID-19. Conclusions: Three doses of mRNA vaccine elicit a strong humoral but a low T cell response, as detected by IGRA, in hematological patients. These findings underscore the importance of completing vaccination before initiating immunosuppressive therapies. Full article

(This article belongs to the Special Issue Immunization of Immunosuppressed Patients)

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20 pages, 2173 KB

Open AccessArticle

Prospective Biomarkers of SARS-CoV-2 Vaccine Seroconversion in Patients with Haematological Malignancies

by Sophie C. Hamann, Katie E. Lineburg, Louise Ng, Annabel Waugh, Stuart Olver, Justine Leach, Christine Bristow, Jyothy Raju, Laetitia Le Texier, Pauline Crooks, Corey Smith, Kristyan Guppy-Coles, Kirk Morris, Michelle Spanevello, Siok-Keen Tey and Andrea S. Henden

Vaccines 2026, 14(3), 201; https://doi.org/10.3390/vaccines14030201 - 25 Feb 2026

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Abstract

Background: SARS-CoV-2 vaccination is crucial for protecting against severe COVID-19 disease; however, patients with haematological malignancies (HM) respond poorly to vaccination due to immunosuppression driven by chemotherapy, targeted cell depletion, and immune dysregulation. We sought to define novel biomarkers that predict effective vaccination [...] Read more.

Background: SARS-CoV-2 vaccination is crucial for protecting against severe COVID-19 disease; however, patients with haematological malignancies (HM) respond poorly to vaccination due to immunosuppression driven by chemotherapy, targeted cell depletion, and immune dysregulation. We sought to define novel biomarkers that predict effective vaccination in patients with HM. Methods: HM patients and healthy controls received SARS-CoV-2 vaccines and were followed for six months post-vaccination. Virus-specific humoral and cellular immune responses were analysed in serum and whole blood pre- and post-vaccination, and serum proteomics was analysed pre-vaccination to identify potential biomarkers for vaccine response. Results: HM patients displayed delayed antibody seroconversion, and 37.5% failed to seroconvert. Baseline proteomic and cellular immune profiles revealed that T-cell-associated chemokines CXCL13 and CRTAM were differentially expressed, with decreased levels seen in vaccine non-responders. Vaccine response was also associated with a reduced frequency of circulating monocytes, greater numbers of B-cells, and a trend toward greater numbers of CD4+ helper cell phenotypes, including T peripheral helper cells pre-vaccination. In vitro generation of COVID-19-specific T-cells from a subset of participants trended towards increased cytotoxic CD4+ and CD8+ T-cell activity in seroconverters and dysfunctional COVID-19-specific T-cell responses in non-seroconverters. Conclusions: These results suggest that HM patients have impaired T-cell immunity, and non-responders may be identified by low levels of serum CXCL13 and CRTAM. This allows for the identification of at-risk patients who would benefit from alternative COVID-19 prophylaxis strategies. Full article

(This article belongs to the Special Issue Immunization of Immunosuppressed Patients)

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17 pages, 382 KB

Open AccessArticle

COVID-19 Vaccination, Hospitalization Rates, and Mortality Differ Between People with Diagnosed Immune Mediated Inflammatory Disease and the General Population: A Population-Based Study

by Carol A. Hitchon, Carole Taylor, Charles N. Bernstein, Christine A. Peschken, Diane Lacaille, Gilaad G. Kaplan, Jessica Widdifield and Ruth Ann Marrie

Vaccines 2025, 13(11), 1130; https://doi.org/10.3390/vaccines13111130 - 2 Nov 2025

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Abstract

Background: Vaccination reduces Coronavirus disease-19 (COVID-19) infection severity. We evaluated COVID-19 vaccine uptake and effectiveness in people with immune mediated inflammatory diseases (pIMIDs) versus the general population. Methods: Using population-based administrative health records, we identified cohorts between 2004 and 2022 with an IMID [...] Read more.

Background: Vaccination reduces Coronavirus disease-19 (COVID-19) infection severity. We evaluated COVID-19 vaccine uptake and effectiveness in people with immune mediated inflammatory diseases (pIMIDs) versus the general population. Methods: Using population-based administrative health records, we identified cohorts between 2004 and 2022 with an IMID (rheumatoid arthritis n = 10,405, systemic autoimmune rheumatic disease n = 5888, inflammatory bowel disease n = 7911, multiple sclerosis n = 3665, psoriasis n = 23,948) who were matched (1:5) by age, sex, and region to general population comparators (n = 243,490) without these IMIDs. Between 1 January 2021 and 31 March 2022, rates of COVID-19 vaccine administration, hospitalizations with COVID-19 (Hosp-C), and all-cause mortality were assessed amongst pIMIDs and comparators using multivariable models. Results: More pIMIDs were vaccinated than comparators (87.3% vs. 84.7%, p < 0.0001). IMID diagnosis, increasing age, female sex, higher socioeconomic status, urban residence, immunotherapy use, and comorbidities were associated with increased odds of receiving at least two vaccine doses. pIMIDs had higher rates of Hosp-C (79 per 100,000, 95% confidence interval (CI) 77.8–80.2) than comparators (51 per 100,000, 95% CI 50.5–51.3; rate ratio 1.55; 95% CI 1.53, 1.58) and greater mortality [pIMID 1758 deaths, 3.61%; comparators (6346 deaths, 2.61%), RR 1.39 95% CI 1.32, 1.46)]. In multivariable analyses, vaccinated status was associated with less Hosp-C (OR 0.27, CI 0.23, 0.32) and death (HR 0.27 CI 0.24, 0.29); the association did not differ between IMID and comparator groups. Conclusions: Although COVID-19 vaccination reduced the risk of Hosp-C and death in both pIMIDs and comparators, pIMIDs remained at higher risk for both. Since SARS-CoV-2 is now endemic, these findings may inform ongoing vaccination recommendations. Full article

(This article belongs to the Special Issue Immunization of Immunosuppressed Patients)

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14 pages, 1165 KB

Open AccessArticle

Durability of Antibody Responses to SARS-CoV-2 Vaccination over 12 Months in Pediatric Inflammatory Bowel Disease

by Sally J. Lawrence, Marina Viñeta Paramo, Frederic Reicherz, Jeffrey N. Bone, Zahra Jama Hussein Shire, Loujain Bilal, Gabriella Guerra, Liam Golding, Pascal M. Lavoie and Kevan Jacobson

Vaccines 2025, 13(6), 549; https://doi.org/10.3390/vaccines13060549 - 22 May 2025

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Abstract

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 [...] Read more.

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

(This article belongs to the Special Issue Immunization of Immunosuppressed Patients)

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16 pages, 1123 KB

Open AccessArticle

Assessment of COVID-19 Vaccine Effectiveness Against SARS-CoV-2 Infection, Hospitalization and Death in Mexican Patients with Metabolic Syndrome from Northeast Mexico: A Multicenter Study

by Beatriz Silva Ramírez, Katia Peñuelas Urquides, Brenda Leticia Escobedo Guajardo, Viviana Leticia Mata Tijerina, Jorge Eleazar Cruz Luna, Roberto Corrales Pérez, Salvador Gómez García, Laura Adiene González Escalante and María Elena Camacho Moll

Vaccines 2025, 13(3), 244; https://doi.org/10.3390/vaccines13030244 - 27 Feb 2025

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Abstract

Background/Objectives: Metabolic syndrome (MetS) is a predisposing factor for severe COVID-19. The effectiveness of COVID-19 vaccines in patients with MetS has been poorly investigated. The aim of this study was to evaluate the effectiveness of COVID-19 vaccination before (BO) and after the Omicron [...] Read more.

Background/Objectives: Metabolic syndrome (MetS) is a predisposing factor for severe COVID-19. The effectiveness of COVID-19 vaccines in patients with MetS has been poorly investigated. The aim of this study was to evaluate the effectiveness of COVID-19 vaccination before (BO) and after the Omicron (AO) SARS-CoV-2 variant in patients with MetS. Methods: This retrospective observational study was carried out in a total of 3194 patients with MetS and a COVID-19 PCR or rapid antigen test. The main outcomes were vaccine effectiveness against infection, hospitalization and death resulting from COVID-19. Results: BO, only two doses of BNT162b2 were effective against infection, this effectiveness was lost AO. Also, with two doses, BNT162b2, ChAdOx1 and CoronaVac were effective against hospitalization BO; however, AO, only BNT162b2 and CoronaVac were effective. Regarding death as an outcome of COVID-19, two doses of BNT162b2 were effective BO, whereas AO, BNT162b2 and CoronaVac were 100% effective. BO the presentation of a sore throat increased after two doses of COVID-19 vaccine regardless of the type, and the presentation of dyspnea diminished after two doses of BNT162b2 and CoronaVac. Conclusions: The SARS-CoV-2 Omicron variant has impacted vaccines’ effectiveness against hospitalization and death in patients with MetS. A tailored vaccination scheme for patients with MetS should be implemented due to the varying effectiveness rates observed in our study. Full article

(This article belongs to the Special Issue Immunization of Immunosuppressed Patients)

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15 pages, 1514 KB

Open AccessArticle

Immunosuppressive Therapy Modifies Anti-Spike IgG Subclasses Distribution After Four Doses of mRNA Vaccination in a Cohort of Kidney Transplant Recipients

by Ignacio Juarez, Isabel Pérez-Flores, Arianne S. Aiffil Meneses, Ana Lopez-Gomez, Natividad Calvo Romero, Beatriz Rodríguez-Cubillo, María Angeles Moreno de la Higuera, Belén Peix-Jiménez, Raquel Gonzalez-Garcia, Beatriz Amorós-Pérez, Benigno Rivas-Pardo, Elvira Baos-Muñoz, Ana Arribi Vilela, Manuel Gómez Del Moral, Ana Isabel Sánchez-Fructuoso and Eduardo Martínez-Naves

Vaccines 2025, 13(2), 123; https://doi.org/10.3390/vaccines13020123 - 25 Jan 2025

Cited by 4 | Viewed by 2129

Abstract

Background: IgG4 is the least immunogenic subclass of IgG. Immunization with mRNA vaccines against SARS-CoV-2, unlike other vaccines, induces an increase in IgG4 against the spike protein in healthy populations. This study investigated whether immunosuppressive therapy affects the immune response, focusing on [...] Read more.

Background: IgG4 is the least immunogenic subclass of IgG. Immunization with mRNA vaccines against SARS-CoV-2, unlike other vaccines, induces an increase in IgG4 against the spike protein in healthy populations. This study investigated whether immunosuppressive therapy affects the immune response, focusing on IgG subclass changes, to four doses of mRNA vaccine in kidney transplant recipients (KTRs). Methods: This study includes 146 KTRs and 23 dialysis patients (DPs) who received three mRNA-1273 vaccine doses and a BNT162b2 booster. We evaluated anti-spike IgG titers and subclasses, T-CD4+ and T-CD8+ cellular responses, and serum neutralizing activity (SNA). Results: At the fourth dose, 75.8% of COVID-19 naïve KTRs developed humoral and cellular responses (vs. 95.7% in DPs). There was a correlation between anti-spike IgG titers/subclasses and SNA (p < 0.001). IgG subclass kinetics after the third/fourth dose differed between COVID-19 naïve KTRs and DPs. Immunosuppressive therapy influenced IgG subclasses: mTOR inhibitors (mTORi) positively influenced IgG1 and IgG3 (p < 0.05), while mycophenolic acid negatively affected IgG1, IgG3, and IgG4 (p < 0.05). SNA is correlated with breakthrough infections after four doses of vaccine in KTRs. mTORi was the only factor associated with SNA > 65% in naïve KTRs [4.29 (1.21–15.17), p = 0.024]. Conclusions: KTRs show weaker cellular and humoral immune responses to mRNA vaccines and a class shift towards non-inflammatory anti-S IgG4 upon booster doses. IgG subclasses show a positive correlation with SNA and are influenced by immunosuppression. Increased SNA after four doses of vaccine is protective against infection. mTORi may benefit non-responding KTRs. Full article

(This article belongs to the Special Issue Immunization of Immunosuppressed Patients)

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Review

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20 pages, 675 KB

Open AccessReview

Vaccination in Oncology Patients: Evidence, Clinical Challenges, and Future Directions

by Alberto Giuseppe Agostara, Silvia Della Torre, Sara Di Bella, Michela Pelliccione, Paola Candido, Valeria Smiroldo, Laura Roazzi, Gabriele Ciarlo, Davide Toniolo, Francesca Zannier and Roberto Bollina

Vaccines 2026, 14(3), 250; https://doi.org/10.3390/vaccines14030250 - 9 Mar 2026

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Abstract

This narrative review provides a comprehensive synthesis of patients with cancer disproportionately affected by vaccine-preventable infectious diseases due to malignancy-related immune dysfunction and treatment-induced immunosuppression. Vaccination represents a cornerstone of supportive care in oncology; however, vaccine uptake remains suboptimal and immune responses are [...] Read more.

This narrative review provides a comprehensive synthesis of patients with cancer disproportionately affected by vaccine-preventable infectious diseases due to malignancy-related immune dysfunction and treatment-induced immunosuppression. Vaccination represents a cornerstone of supportive care in oncology; however, vaccine uptake remains suboptimal and immune responses are frequently attenuated, particularly in patients with hematological malignancies and those receiving highly immunosuppressive therapies. This review provides a comprehensive synthesis of current evidence on vaccine immunogenicity, clinical effectiveness, and safety in oncology patients. We discuss immunological mechanisms underlying impaired vaccine responses, summarize evidence for major vaccines recommended in oncology practice, and address key clinical challenges such as timing relative to anticancer therapies, heterogeneity of immune responses, and vaccine hesitancy. An extended discussion highlights emerging strategies, including booster dosing, adjuvanted vaccines, and personalized vaccination approaches. Finally, future perspectives are outlined to improve integration of vaccination into routine oncology care. Full article

(This article belongs to the Special Issue Immunization of Immunosuppressed Patients)

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16 pages, 256 KB

Open AccessReview

COVID-19 Vaccination in Patients with Hematological Malignances

by Massimo Franchini, Fabrizio Maggi and Daniele Focosi

Vaccines 2025, 13(5), 465; https://doi.org/10.3390/vaccines13050465 - 25 Apr 2025

Cited by 2 | Viewed by 4563

Abstract

Patients with hematologic malignancies (HM) represent a population particularly vulnerable to infections due to their cancer-related immune deficiency and the immunosuppressive treatment they are administered. Accordingly, a high hospitalization and mortality rate has been consistently reported in such a frail population during the [...] Read more.

Patients with hematologic malignancies (HM) represent a population particularly vulnerable to infections due to their cancer-related immune deficiency and the immunosuppressive treatment they are administered. Accordingly, a high hospitalization and mortality rate has been consistently reported in such a frail population during the first COVID-19 pandemic waves. After a brief description of the clinical impact of SARS-CoV-2 infection in patients with blood cancers, this narrative review is focused on the protective effect of COVID-19 vaccines in patients with HM. All in all, the results from the literature analysis indicate that booster shots in fully vaccinated HM patients are significantly able to increase seroconversion rates, which represent the best surrogate of vaccine efficacy. Despite these encouraging data, concerns still remain regarding the lower immune responses to COVID-19 vaccines, even to booster doses, in severely immunosuppressed HM patients, such as those receiving anti-CD20 monoclonal antibody therapies and hematopoietic stem cell transplants. Full article

(This article belongs to the Special Issue Immunization of Immunosuppressed Patients)

Other

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23 pages, 1767 KB

Open AccessSystematic Review

Efficacy and Safety of mRNA-Based COVID-19 Vaccines in Solid Organ Transplant Recipients: A Systematic Review and Meta-Analysis

by Maya Alkhidir and Kannan Sridharan

Vaccines 2026, 14(1), 72; https://doi.org/10.3390/vaccines14010072 - 8 Jan 2026

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Abstract

Background: Solid organ transplant recipients (SOTRs) are highly vulnerable to severe COVID-19 infection, yet initial vaccine trials provided limited data on efficacy and safety in this immunocompromised population. Heterogeneous seroconversion rates and conflicting safety reports complicate the formulation of clear clinical guidelines. This [...] Read more.

Background: Solid organ transplant recipients (SOTRs) are highly vulnerable to severe COVID-19 infection, yet initial vaccine trials provided limited data on efficacy and safety in this immunocompromised population. Heterogeneous seroconversion rates and conflicting safety reports complicate the formulation of clear clinical guidelines. This systematic review and meta-analysis aim to aggregate existing evidence to determine the precise seroconversion and safety profiles of COVID-19 vaccines and identify key factors influencing immune response in SOTRs. Methods: A comprehensive literature search was conducted identifying 125 studies evaluating WHO/FDA-authorized vaccines in SOTRs. Outcomes were the pooled seroconversion proportion and safety profile. Subgroup analyses were performed based on vaccine type, transplanted organ, number of doses, and prior SARS-CoV-2 infection status, confirmed by leave-one-out sensitivity analysis and bootstrap methods. Results: Most studies assessed mRNA-based vaccines (123/125, 98.4%). The overall pooled seroconversion proportion across all SOTRs was significantly blunted at 0.49 (95% CI, 0.43 to 0.55), demonstrating high heterogeneity (I² = 94.2%). Seroconversion showed a clear positive dose–response relationship, increasing from 27% after one dose to 84% after four doses. Prior COVID-19 infection was the strongest predictor of a response, resulting in a pooled seroconversion of 0.90 (95% CI, 0.82 to 0.94; I² = 0%). Organ-specific analyses revealed the highest response in Liver recipients (0.80) and the lowest in Lung recipients (0.29). Vaccine platform analysis showed that the highest response was with mRNA-1273 (0.55) and the lowest with CoronaVac (0.29). The safety profile was limited. Conclusions: SOTRs exhibit profound hypo responsiveness to COVID-19 vaccines; however, the extreme heterogeneity observed across studies necessitates a cautious interpretation of pooled seroconversion estimates. While the data indicates a significant dose–response relationship favoring an aggressive, multi-dose strategy, the apparent safety profile may reflect under-reporting and limited follow-up rather than confirmed safety equivalence. Rare but clinically critical outcomes, such as acute allograft rejection, remain inadequately characterized in the current literature. Consequently, while the prioritization of multi-dose regimens and hybrid immunity is supported to maximize protection, clinicians must recognize that individual responses remain highly variable, and the long-term immunological impact of repeated stimulation requires further standardized investigation. Full article

(This article belongs to the Special Issue Immunization of Immunosuppressed Patients)

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9 pages, 502 KB

Open AccessBrief Report

Serological Response After the Fourth Dose of COVID-19 Vaccine in Highly Immunosuppressed Patients

by Abelardo Claudio Fernández Chávez, Paula Navarro López, Ana De Andrés Martín, Daniel Leonardo Sánchez Carmona, Guillermo Yovany Ordoñez León and Jesús María Aranaz Andrés

Vaccines 2025, 13(10), 994; https://doi.org/10.3390/vaccines13100994 - 23 Sep 2025

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Introduction (Objectives): This study aimed to evaluate the serological response to a fourth dose of mRNA COVID-19 vaccine in patients with conditions that confer a high risk of severe disease, particularly those with high-level immunosuppression. Methods: An observational study was conducted at the [...] Read more.

Introduction (Objectives): This study aimed to evaluate the serological response to a fourth dose of mRNA COVID-19 vaccine in patients with conditions that confer a high risk of severe disease, particularly those with high-level immunosuppression. Methods: An observational study was conducted at the Ramón y Cajal University Hospital between February and August 2022. Adults (≥18 years) with high-risk conditions who had received four doses of either BNT162b2 or mRNA-1273 were included. Anti-spike IgG levels were measured ≥14 days post-vaccination. An adequate response was defined as an antibody concentration ≥260 BAU/mL. Results: A total of 943 patients were analyzed; 846 (89.7%) achieved an adequate response. In the bivariate analysis, patients aged 60–74 years had a higher risk of inadequate response compared to those aged 18–39 years (OR 1.824 vs. OR 0.257). Female sex was associated with a higher risk of inadequate response (OR 1.522; 95% CI: 0.974–2.371). In multivariable logistic regression, patients with high immunosuppression had a higher, though not statistically significant, risk of inadequate response compared with those without. Discussion: Our findings are consistent with international evidence suggesting that age and certain clinical factors reduce vaccine immunogenicity. The observed paradoxical effect of sex could reflect the higher prevalence of aggressive immunosuppressive therapies among women in the study cohort. Conclusions: Most immunosuppressed patients achieved seroconversion after the fourth dose. These results underscore the need for tailored vaccination strategies and additional measures in highly immunosuppressed subgroups. Full article

(This article belongs to the Special Issue Immunization of Immunosuppressed Patients)

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