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Microbiome–Immune Interaction and Harnessing for Next-Generation Vaccines Against Highly Pathogenic Avian Influenza in Poultry
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Toxoplasma gondii at the Host Interface: Immune Modulation and Translational Strategies for Infection Control
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Efficacy and Safety of Anti-Respiratory Syncytial Virus Monoclonal Antibody Nirsevimab in Neonates: A Real-World Monocentric Study
Journal Description
Vaccines
Vaccines
is an international, peer-reviewed, open access journal published monthly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), PubMed, PMC, Embase, CAPlus / SciFinder, and other databases.
- Journal Rank: JCR - Q2 (Medicine, Research and Experimental) / CiteScore - Q1 (Pharmacology (medical))
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 19.6 days after submission; acceptance to publication is undertaken in 2.8 days (median values for papers published in this journal in the first half of 2025).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
3.4 (2024);
5-Year Impact Factor:
3.7 (2024)
Latest Articles
Effect of Influenza Vaccination on Mortality and Heart Failure Hospitalization in Heart Failure Patients
Vaccines 2025, 13(10), 1055; https://doi.org/10.3390/vaccines13101055 - 15 Oct 2025
Abstract
Background: The association of influenza vaccination and heart failure (HF) hospitalization and mortality in Thai HF patients is unknown. Objective: We wished to investigate associations between receiving an influenza vaccine and all-cause death or HF hospitalization in HF patients. Methods: We retrospectively reviewed
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Background: The association of influenza vaccination and heart failure (HF) hospitalization and mortality in Thai HF patients is unknown. Objective: We wished to investigate associations between receiving an influenza vaccine and all-cause death or HF hospitalization in HF patients. Methods: We retrospectively reviewed medical records from two large tertiary-care centers in Thailand (Ramathibodi Hospital and Maharaj Nakorn Chiang Mai Hospital) with newly diagnosed heart failure between 2013 and 2020 in an outpatient clinic. We examined the relationship between influenza vaccination and outcomes in a propensity-adjusted model. Results: Of 588 patients, 181 (31%) received an influenza vaccination. During a median follow-up of 57 months, influenza vaccination was associated with a 56% reduction in the risk of HF hospitalization or death (HF hospitalization or all-cause death: HR: 0.44; 95% CI: 0.31–0.63; p < 0.001) in an unadjusted analysis. After propensity score adjustment, influenza vaccination, however, was not associated with a reduced risk of all-cause death but was associated with a reduced risk of HF hospitalization (ATE: 3.06 years; 95% CI: 0.14 to 5.98; p = 0.04). Conclusions: In patients with HF, influenza vaccination was not associated with a reduced risk of the composite of all-cause death or HF hospitalization after adjustment for confounders.
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(This article belongs to the Section Influenza Virus Vaccines)
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Self-Reporting of Post-Vaccination Symptoms in the COVID-19 Vaccination Process for Teachers in a North Region of Poland
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Tadeusz Jędrzejczyk, Anna Tyrańska-Fobke, Agata Konieczna, Daniel Ślęzak, Monika Waśkow, Katarzyna Brzychcy, Piotr Robakowski and Marlena Robakowska
Vaccines 2025, 13(10), 1054; https://doi.org/10.3390/vaccines13101054 - 14 Oct 2025
Abstract
Background: Poland was one of only 10 European countries listed teachers as a priority group for vaccination against COVID-19 among National Vaccination Program (NVP). The aim of this study was to analyse post-vaccination symptoms self-reported by teachers vaccinated under the national COVID-19 vaccination
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Background: Poland was one of only 10 European countries listed teachers as a priority group for vaccination against COVID-19 among National Vaccination Program (NVP). The aim of this study was to analyse post-vaccination symptoms self-reported by teachers vaccinated under the national COVID-19 vaccination programme. Methods: The presented cross-sectional survey was conducted among teachers from all levels of education in public and non-public institutions, who received the SARS-CoV-2 virus vaccination campaign with the vaccine from AstraZeneca as part of the NVP. The survey was conducted using an original, self-designed questionnaire prepared for this study and distributed to teachers in the form of an online survey via email. Bayesian logistic and linear regression were used to estimate the relationship between predictors and dependent variables. Results: A total of 4622 teachers took part in the survey. Of this number, 3908 teachers declared that they had taken the vaccine. (84.5%). In the study group, self-reported late post-vaccination reactions were very strongly [logBF > 3.4] associated with both gender and age. In contrast, self-reporting of serious late post-vaccination symptoms other than fever was very strongly associated only with gender. Only a small proportion of teachers (from 1.45% to 5.34% depending on age and gender) self-reported immediate post-vaccination reaction (up to 15 min after injection). Conclusions: Self-reporting of symptoms is a valuable tool for monitoring the effectiveness and safety of vaccinations and can also contribute to increased satisfaction with the vaccination process, especially when patients are made aware that post-vaccination symptoms are a natural sign of the body’s immune response.
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(This article belongs to the Special Issue Safety and Side Effects in SARS-CoV-2 Vaccine)
Open AccessArticle
B7 Family Molecule VSIG4 Regulates Pulmonary Anti-Influenza Immune Responses via C-Type Lectin Signal Pathway
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Jianxin Zhu, Dan Lu, Liangyan Zhang, Zhili He, Tianxinyu Ma, Yakun Sun, Wenjing Yu, Xiaolan Yang, Yeqing Tu, Yitai Fang, Deyu Li, Rui Zheng, Tao Li, Jin Zhao and Hui Wang
Vaccines 2025, 13(10), 1053; https://doi.org/10.3390/vaccines13101053 - 14 Oct 2025
Abstract
Background: As the member of the B7 family, V-set and immunoglobulin domain-containing 4 (VSIG4) plays an essential role in regulating immune responses against bacterial infection, autoimmune disease, and chronic viral infection. However, the role of VSIG4 in acute viral infections remains largely
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Background: As the member of the B7 family, V-set and immunoglobulin domain-containing 4 (VSIG4) plays an essential role in regulating immune responses against bacterial infection, autoimmune disease, and chronic viral infection. However, the role of VSIG4 in acute viral infections remains largely unclear. Methods: Here, we constructed a gene-targeted VSIG4-deficient mouse model and then infected it with influenza to explore the detailed VSIG4-involved mechanism. Results: Our results demonstrated that the gene-deficient mice exhibited reduced survival rates, ranging from 25% to 50%, after being infected with different influenza virus strains. At the sites of infection, an increased number of CD8+ T cells, along with heightened expression of pro-inflammatory cytokines, e.g., Il-6 and TNFα, may have contributed to tissue damage. The recombinant VSIG4 protein slightly improved protection from the influenza challenge, suggesting regulatory functions of VSIG4 during infection. Using in vitro cell models, we show that the type C lectin receptor pathway member DC-SIGNR1 (CD209) is an essential factor during acute virus infection. The affinity and CO-IP tests indicated an interaction between CD209 and VSIG4, but not through protein modification. Conclusions: Therefore, VSIG4 functionally protected mice by regulating the type C lectin receptor pathway to inhibit excessive Th1 immune responses and inflammation. Our findings highlight the importance of considering immune homeostasis in the development of therapies for severe infections.
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(This article belongs to the Section Pathogens-Host Immune Boundaries)
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Establishment of Immune Biobank for Vaccine Immunogenicity Prediction Using In Vitro and In Silico Methods Against Porcine Reproductive and Respiratory Syndrome Virus
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Chaitawat Sirisereewan, John J. Byrne, Lanre Sulaiman, Abigail Williams, Ben M. Hause, Juliana Bonin Ferreira, Glen W. Almond, Benjamin Gabriel, Anne S. De Groot, Tobias Käser, Gustavo Machado and Elisa Crisci
Vaccines 2025, 13(10), 1052; https://doi.org/10.3390/vaccines13101052 - 14 Oct 2025
Abstract
Background/Objectives: Porcine reproductive and respiratory syndrome virus (PRRSV) remains one of the most economically significant pathogens in the global swine industry. Despite the availability of commercial vaccines for over three decades, they fail to induce sterile immunity and often provide inconsistent protection against
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Background/Objectives: Porcine reproductive and respiratory syndrome virus (PRRSV) remains one of the most economically significant pathogens in the global swine industry. Despite the availability of commercial vaccines for over three decades, they fail to induce sterile immunity and often provide inconsistent protection against heterologous PRRSV strains. This study aimed to predict vaccine immunogenicity by detecting strain-specific immune responses that related to an immune correlate of protection (CoP) against different PRRSV-2 strains. Methods: Post-weaning pigs were vaccinated with five commercially available PRRSV-2 vaccines or received sterile PBS injection as a control. At 28 days post-vaccination (dpv), all pigs were humanely euthanized for large-volume blood collection to isolate peripheral blood mononuclear cells (PBMCs) and plasma, establishing the immune bank. PBMCs and plasma from each group were then tested against six PRRSV-2 strains to evaluate immune responses. In addition, T cell epitope coverage between vaccine and field PRRSV-2 strains was assessed using the EpiCC (in silico) tool to enhance predictive capacity. Results: While neutralizing antibodies were undetectable in all vaccinated pigs at 28 dpv, PRRSV-specific IFNγ–producing cells were detected at various levels in each vaccinated group following restimulation with different PRRSV-2 strains. Additionally, a positive correlation was observed for the EpiCC coverage of the N gene and mean IFNγ responses to VR2332 (SLA class I and II) and NC24-6 (SLA class II). Conclusions: The PRRSV immune bank demonstrated potential as a tool for predicting vaccine immunogenicity against different PRRSV-2 strains and EpiCC provides additional information on T cell epitope cross conservation. The combined approach may provide a valuable framework for selecting PRRSV vaccines for more effective prevention and control in endemic areas.
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(This article belongs to the Special Issue Animal Vaccines: 2nd Edition)
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Boosting RSV Immunization Uptake in The Netherlands: (Expectant) Mothers and Healthcare Professionals’ Insights on Different Strategies
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Lisanne van Leeuwen, Lisette Harteveld, Lucy Smit, Karlijn Vollebregt, Debby Bogaert and Marlies van Houten
Vaccines 2025, 13(10), 1051; https://doi.org/10.3390/vaccines13101051 - 14 Oct 2025
Abstract
Background: Respiratory syncytial virus (RSV) is a major cause of infant respiratory illness, leading to significant hospitalizations. Two preventive strategies exist: maternal vaccination and a long-acting monoclonal antibody for neonates. In The Netherlands, neonatal immunization is planned to start from autumn 2025 onward,
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Background: Respiratory syncytial virus (RSV) is a major cause of infant respiratory illness, leading to significant hospitalizations. Two preventive strategies exist: maternal vaccination and a long-acting monoclonal antibody for neonates. In The Netherlands, neonatal immunization is planned to start from autumn 2025 onward, contingent on acceptance by parents and healthcare professionals. Maternal vaccination is already available at own costs. Understanding acceptance, perceptions, and barriers is critical for effective implementation. This study explores these factors to inform strategies for optimal uptake. Methods: This mixed-method study involved semi-structured online interviews with 21 (expectant) mothers (EMs) and 32 healthcare professionals (HCPs) involved in maternal and neonatal care (e.g., pediatricians, youth doctors/nurses, obstetricians, midwives, and general practitioners) and a quantitative descriptive analysis of factors influencing EM choices. Interviews were transcribed and thematically analyzed. Results: Both EMs and HCPs showed strong support for RSV immunization, with a preference for maternal vaccination or a combined approach. Concerns about neonatal injections during the sensitive postpartum period and unfamiliarity with newborn injections (e.g., vitamin K) influenced preferences. EMs noted hesitation about additional pregnancy/postpartum vaccinations, emphasizing the importance of well-timed interventions. HCPs highlighted logistical challenges, such as defining responsibilities, navigating National Immunization Program (NIP) changes, and ensuring readiness. All interviewed individuals value the option to choose between strategies, necessitating informed decision-making and respect for preferences. EMs make their final decision together with their partner, supported by expert information and their personal environment. Conclusions: Support for RSV immunization is high, with maternal vaccination preferred, though neonatal immunization is accepted if appropriately timed. Providing clear personalized and consistent information, heightened public awareness of RSV’s impact, respecting individual choices, and offering options are key to maximizing uptake.
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(This article belongs to the Special Issue Vaccination Strategies for Global Public Health)
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Prevalence of High-Risk Human Papillomaviruses (HPV) in Slovenian Women Attending Organized National Cervical Cancer Screening 14 Years After Implementation of the National HPV Vaccination Program
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Mateja Lasič, Anja Oštrbenk, Špela Smrkolj, Klara B. Bohinc, Ana Pflaum and Mario Poljak
Vaccines 2025, 13(10), 1050; https://doi.org/10.3390/vaccines13101050 - 13 Oct 2025
Abstract
Background/Objectives: To assess overall and type-specific HPV vaccine effectiveness in central and eastern Europe (CEE), the age-stratified prevalence of cervical HPV infection was determined among Slovenian women aged 20 to 64 attending a cervical cancer screening program 14 years after implementation of
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Background/Objectives: To assess overall and type-specific HPV vaccine effectiveness in central and eastern Europe (CEE), the age-stratified prevalence of cervical HPV infection was determined among Slovenian women aged 20 to 64 attending a cervical cancer screening program 14 years after implementation of a national HPV vaccination program, which was then compared with 2009–2010 pre-vaccination data using the same methodological approach. Methods: Cervical samples of 4419 women were tested in 2023–2025 using the clinically validated Alinity m HR HPV Assay, and individual HPV types were determined by the Allplex HPV HR Detection assay. Results were compared with 2009–2010 pre-vaccination data generated using the same assay on an age-range matched cohort of women. Results: The overall prevalence of the 14 Alinity-targeted HPV types was 10.0% in 2023–2025 versus 13.3% in 2009–2010 (p < 0.001). HPV16 prevalence declined from 3.5% to 1.5% (p < 0.001), and HPV18 prevalence from 1.1% to 0.5% (p = 0.005). In women aged 20 to 24 with 40% uptake of quadrivalent HPV vaccine, overall HPV prevalence dropped from 25.3% to 12.8% (p < 0.001). No single case of HPV16/HPV18 infection was detected among vaccinated women. Conclusions: The first large-scale, systematic, and methodologically consistent study of HPV vaccine effectiveness in CEE showed a substantial reduction in high-risk HPV prevalence after implementation of the national program, with the greatest decline among women aged 20 to 24, who harbored the highest HPV burden in the pre-vaccination era. These locally acquired data will considerably inform public health strategies on cervical cancer elimination in CEE.
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(This article belongs to the Special Issue HPV Vaccination and Primary HPV Screening)
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Open AccessCorrection
Correction: Castro et al. Stakeholders’ Understanding of European Medicine Agency’s COVID-19 Vaccine Information Materials in EU and Regional Contexts. Vaccines 2023, 11, 1616
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Indiana Castro, Marie Van Tricht, Nicole Bonaccorso, Martina Sciortino, Juan Garcia Burgos, Claudio Costantino and Rosa Gonzalez-Quevedo
Vaccines 2025, 13(10), 1049; https://doi.org/10.3390/vaccines13101049 - 13 Oct 2025
Abstract
The author would like to make the following correction to this publication [...]
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Immunogenicity and Contraceptive Potential of a Classical Swine Fever Viral Vector Live Vaccine Strain Containing Pig Gonadotropin-Releasing Hormone
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Dong-Jun An, Ji-Hee Shin, SeEun Choe, Young-Hyeon Lee, Min-Kyung Jang, Byung-Hyun An, Gyu-Nam Park, Yun-Sang Cho and Kyung-Soo Chang
Vaccines 2025, 13(10), 1048; https://doi.org/10.3390/vaccines13101048 - 12 Oct 2025
Abstract
Background: Classical swine fever virus (CSFV) is a highly contagious and fatal disease in pigs and wild boars. While hunting and bait vaccination are effective for CSFV eradication, additional strategies are needed to control wild boar populations. This study aimed to develop an
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Background: Classical swine fever virus (CSFV) is a highly contagious and fatal disease in pigs and wild boars. While hunting and bait vaccination are effective for CSFV eradication, additional strategies are needed to control wild boar populations. This study aimed to develop an oral vaccine, Flc-LOM-GnRHx3, by inserting gonadotropin-releasing hormone (GnRH) epitopes into the Flc-LOM clone. Methods: The Flc-LOM-GnRHx3 strain was rescued from CPK cells and propagated to high titers in MDBK cells. Male boars (20 weeks old) received three doses (105.0 TCID50/ml/dose) of Flc-LOM-GnRHx3 either orally or intramuscularly at 2-week intervals. Anti-CSFV E2 antibodies were detected via immunofluorescence and Western blotting. Results: Both vaccination routes induced anti-GnRH antibodies and reduced testosterone levels. Testis size and weight were slightly lower than controls, with seminiferous tubule and spermatid deformities observed in 52.5% of intramuscularly vaccinated pigs and 20.8% of orally vaccinated pigs. Conclusions: Flc-LOM-GnRHx3 demonstrates potential as a dual-function oral vaccine that can eradicate CSFV and impair reproductive capacity in wild boars, offering a novel approach for integrated disease control and population management.
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(This article belongs to the Special Issue Classical Swine Fever Virus Vaccines)
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Precautionary Health Behaviours as Potential Confounders in COVID-19 Vaccine Effectiveness Studies
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Chloé Wyndham-Thomas, Leonie de Munter, Kok Yew Ngew, Sanskruti Gaikwad, Konstantina Chatzikonstantinidou, Antonio Carmona, Charlotte Martin, Gerrit Luit ten Kate, Nicolas Praet, Wilhelmine Meeraus, Matthew D. Rousculp and Kaatje Bollaerts
Vaccines 2025, 13(10), 1047; https://doi.org/10.3390/vaccines13101047 - 12 Oct 2025
Abstract
Background/Objectives: Precautionary health behaviours (PHBs), such as hand-washing or self-isolation, are non-pharmaceutical interventions used to reduce SARS-CoV-2 transmission. We investigated the potential confounding by PHBs of COVID-19 vaccine effectiveness (VE) estimates in a subset of study participants enrolled in id.DRIVE. Methods:
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Background/Objectives: Precautionary health behaviours (PHBs), such as hand-washing or self-isolation, are non-pharmaceutical interventions used to reduce SARS-CoV-2 transmission. We investigated the potential confounding by PHBs of COVID-19 vaccine effectiveness (VE) estimates in a subset of study participants enrolled in id.DRIVE. Methods: The id.DRIVE COVID-19 VE study (formerly COVIDRIVE) is a European multicentre test-negative case–control study estimating COVID-19 VE against hospitalisation due to laboratory-confirmed SARS-CoV-2 in patients with severe acute respiratory infection. All adults (≥18 y) prospectively enrolled between 16 November 2021 and 16 August 2023 at three sites were invited to complete a PHB survey capturing indicators of PHBs in the 3 months preceding admission. Fisher’s exact test with Bonferroni-adjusted threshold was used to measure the level of association between PHB indicators and both COVID-19 vaccine status and SARS-CoV-2 test result. VE estimates were generated with and without adjustment for PHBs. Results: PHBs were modified over time, with higher precautionary attitudes in the first COVID-19 vaccine booster season (2021–2022) compared to the second one (2022–2023). For the first booster season, PHBs were positively associated with exposures (vaccination status) and outcomes (case or control status). Adjusting for PHBs led to a 6 to 9 percentage-point increase in VE estimates. Conversely, no confounding by PHBs was observed in the second booster season. Conclusions: PHBs should be considered a possible confounder of COVID-19 VE studies. Further research is needed to define when PHBs should be integrated into VE models, as the level of confounding may differ according to the study population and the epidemiological context.
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(This article belongs to the Special Issue Advance Public Health Through Vaccination)
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Effect of Influenza Vaccination on the Disease Severity and Viral Load Among Adult Outpatients and Inpatients
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Alexander Domnich, Vincenzo Paolozzi, Giada Garzillo, Andrea Orsi and Giancarlo Icardi
Vaccines 2025, 13(10), 1046; https://doi.org/10.3390/vaccines13101046 - 10 Oct 2025
Abstract
Background: Some studies suggest that, thanks to the mechanisms of immune-mediated attenuation, influenza vaccination reduces severity of influenza illness in breakthrough infections. This study aimed to assess whether influenza vaccination attenuates severity of laboratory-confirmed influenza among Italian adults. Methods: This secondary
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Background: Some studies suggest that, thanks to the mechanisms of immune-mediated attenuation, influenza vaccination reduces severity of influenza illness in breakthrough infections. This study aimed to assess whether influenza vaccination attenuates severity of laboratory-confirmed influenza among Italian adults. Methods: This secondary analysis included all influenza cases detected during respiratory surveillance studies conducted in outpatient and inpatient settings in Genoa (Italy), throughout the 2023/2024 and 2024/2025 seasons. Here, we compared viral load and the count of influenza-related symptoms in outpatients, alongside all-cause in-hospital mortality and radiologically confirmed pneumonia in inpatients, between vaccinated and unvaccinated adults. Results: The study included 188 influenza cases diagnosed in primary care and 281 influenza cases identified among inpatients. Of these, 37.2% and 31.7%, respectively, were vaccinated, constituting breakthrough infections. Compared to unvaccinated adults, vaccinated outpatients had a slightly lower viral load (difference in cycle threshold values of 1.36 corresponding to about 0.51 log10 reduction in the number of copies/mL; p = 0.077), primarily driven by influenza A(H1N1)pdm09. Vaccinated outpatients also reported 9% fewer influenza-related symptoms than unvaccinated counterparts [prevalence ratio 0.91; 95% confidence interval (CI): 0.84, 0.99]. Among hospitalized older adults, influenza vaccination was associated with 64% reduced odds of in-hospital death (odds ratio 0.36; 95% CI: 0.12, 0.94). Conversely, no association between vaccination and development of pneumonia was found. Conclusions: This study corroborates the idea that influenza vaccination attenuates disease severity in breakthrough infections. These effects are, however, dependent on the measure of severity used.
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(This article belongs to the Special Issue The Effectiveness of Influenza Vaccine)
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Health Technology Assessment of mRNA Vaccines: Clinical, Economic, and Public Health Implications
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Giovanni Genovese, Caterina Elisabetta Rizzo and Cristina Genovese
Vaccines 2025, 13(10), 1045; https://doi.org/10.3390/vaccines13101045 - 10 Oct 2025
Abstract
Health Technology Assessment (HTA) is a multidimensional and multidisciplinary approach for analyzing the medical–clinical, social, organizational, economic, ethical, and legal implications of a technology, through the evaluation of multiple dimensions such as efficacy, safety, costs, and social–organizational impact. In the healthcare context, “technology”
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Health Technology Assessment (HTA) is a multidimensional and multidisciplinary approach for analyzing the medical–clinical, social, organizational, economic, ethical, and legal implications of a technology, through the evaluation of multiple dimensions such as efficacy, safety, costs, and social–organizational impact. In the healthcare context, “technology” refers to any tool—including pharmaceuticals (or, in this case, vaccines)—that is applied to healthcare practice. HTA focuses on assessing both the real and potential effects of a given technology, either prospectively or throughout its life cycle, as well as the consequences that the introduction or exclusion of an intervention may have on the healthcare system, the economy, and society at large.
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(This article belongs to the Special Issue Communicable Diseases: New and Old Therapies and Preventive Strategies, 2nd Edition)
Open AccessPerspective
Advancing Inequality Monitoring in Immunization: Reflecting on 10 Years of WHO Contributions
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Nicole Bergen, Katherine Kirkby, Anne Schlotheuber and Ahmad Reza Hosseinpoor
Vaccines 2025, 13(10), 1044; https://doi.org/10.3390/vaccines13101044 - 10 Oct 2025
Abstract
Major immunization programs and initiatives have prioritized the advancement of equity in immunization. Over the past decade, the World Health Organization has made contributions to understanding inequalities in immunization, including global analyses of immunization inequality as well as tools for knowledge dissemination and
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Major immunization programs and initiatives have prioritized the advancement of equity in immunization. Over the past decade, the World Health Organization has made contributions to understanding inequalities in immunization, including global analyses of immunization inequality as well as tools for knowledge dissemination and capacity strengthening. This article provides an overview of these contributions, highlighting key findings of scholarly reports and journal articles and identifying areas for further research and development to expand monitoring efforts and enhance their impact. Global analyses have primarily drawn from household survey data to explore inequalities related to economic status, education, gender, and geography. Reports and articles address childhood immunization, COVID-19 vaccine indicators, and maternal tetanus protection. Inequalities were reported across all dimensions, with variation by country and income grouping. Time trends generally suggest persistent, though narrowing, inequalities. Areas for further development include the following: increasing awareness and political support for advancing equity in immunization; expanding the collection, availability, and use of disaggregated immunization data; continuous capacity building of inequality monitoring, especially at national and subnational levels; adapting inequality monitoring practices to changing contexts and priorities; strengthening the links between data/evidence and action/impact; and building on existing partnerships and collaborations.
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(This article belongs to the Special Issue Inequality in Immunization 2025)
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Biotechnology and the Future of Vaccines—From Novel Routes and Vectors to Safety, Efficacy, and Global Impact
by
Tsu-Hsiang Kuo and Yuan-Chuan Chen
Vaccines 2025, 13(10), 1043; https://doi.org/10.3390/vaccines13101043 - 10 Oct 2025
Abstract
Vaccines remain one of the greatest achievements in biomedical science, credited with the eradication of smallpox, the near-elimination of polio and the prevention of many deaths from infectious diseases [...]
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(This article belongs to the Special Issue Biotechnologies Applied in Vaccine Research)
Open AccessArticle
Serological Response to COVID-19 Vaccination in Saudi Arabia: A Comparative Study of IgG and Neutralising Antibodies Across Vaccine Platforms
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Mariam M. AlEissa, Ahdab A. Alsaieedi, Reema Alduaiji, Fahad Almsned, Yousif AlDossary, Nada Saleh, Raghad A. AlQurashi, Esraa A. Hawsa, Muath b Ben Shaded, Amer M. Alshehri, Osamah T. Khojah, Eyad Y. Abu Sarhan, Hamad H. Alonazi, Walid A. Nouh, Khalid H. AlAnazi, Sami S. Almudrra, Khaled I. AlAbdulkareem, Abdullah AlJurayyan and Abdullah M. Asiri
Vaccines 2025, 13(10), 1042; https://doi.org/10.3390/vaccines13101042 - 10 Oct 2025
Abstract
Background: In the Kingdom of Saudi Arabia, various COVID-19 vaccines were administered during the pandemic. However, region-specific real-word comparative data on their immunogenicity remain limited. This study aimed to assess the serological responses to Pfizer-BioNTech (BNT162b2), Moderna (mRNA-1273), and AstraZeneca (ChAdOx1 nCoV-19)
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Background: In the Kingdom of Saudi Arabia, various COVID-19 vaccines were administered during the pandemic. However, region-specific real-word comparative data on their immunogenicity remain limited. This study aimed to assess the serological responses to Pfizer-BioNTech (BNT162b2), Moderna (mRNA-1273), and AstraZeneca (ChAdOx1 nCoV-19) vaccines in a diverse population living in KSA. Methods: This observational study included 236 adults recruited from vaccination sites in Riyadh. Participants provided serum samples at predefined intervals: before the first dose, after the first dose, after the second dose, and post-vaccination infection (if applicable). IgG and neutralising antibodies were quantified using ELISA assays. Demographic and vaccination data, and their associations with antibody responses, were evaluated. Results: At baseline, 75.4% of participants were positive for SARS-CoV-2 IgG, suggesting high prior exposure. Marked incremental increases in IgG levels were observed after each vaccine dose. Both Moderna and Pfizer elicited stronger responses, with Pfizer inducing the strongest early response and Moderna achieving the highest overall titres. Among IgG-positive individuals, neutralising antibodies were detected in 98.1%. There were no statistically significant differences by age or gender, although males tended to show higher mean titres. Heterologous vaccine schedules induced comparable or enhanced immunogenicity relative to homologous schedules, supporting their use in flexible immunisation strategies. Conclusions: All COVID-19 vaccines administered in Saudi Arabia elicited robust antibody responses, particularly the mRNA-based vaccines. Our findings support their continued use and justify varied vaccination approaches, including mix-and-match booster strategies, to enhance community immunity.
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(This article belongs to the Section COVID-19 Vaccines and Vaccination)
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Production of Clinical-Grade SARS-CoV-2 Spike Ferritin Nanoparticle Protein Immunogen by Transient Transfection
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Agnes Hajduczki, William C. Chang, Rafael De La Barrera, James F. Wood, Wei-Hung Chen, Elizabeth J. Martinez, Jaime L. Jensen, Rajeshwer S. Sankhala, Clayton Smith, Alexander Anderson, Elaine B. Morrison, Caroline E. Peterson, Phyllis A. Rees, Sandrine Soman, Caitlin Kuklis, Aslaa Ahmed, Jocelyn King, Farooq Nasar, Courtney Corbitt, Misook Choe, Paul V. Thomas, Michelle Zemil, Lindsay Wieczorek, Victoria R. Polonis, Helen M. Dooley, John R. Mascola, Natalie de Val, Gary R. Matyas, Mangala Rao, Gregory D. Gromowski, Kayvon Modjarrad, Sandhya Vasan, Jeffrey W. Froude, Nelson L. Michael, M. Gordon Joyce and Stasya Zarlingadd
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Vaccines 2025, 13(10), 1041; https://doi.org/10.3390/vaccines13101041 - 9 Oct 2025
Abstract
Background/Objectives: In response to the COVID-19 pandemic, we developed a vaccine candidate against SARS-CoV-2. Spike Ferritin Nanoparticle (SpFN) comprises 24 identical prefusion-stabilized spike proteins anchored to a self-assembled nanoparticle. Organized along the three-fold axis of the ferritin particle, eight SARS-CoV-2 spike trimers
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Background/Objectives: In response to the COVID-19 pandemic, we developed a vaccine candidate against SARS-CoV-2. Spike Ferritin Nanoparticle (SpFN) comprises 24 identical prefusion-stabilized spike proteins anchored to a self-assembled nanoparticle. Organized along the three-fold axis of the ferritin particle, eight SARS-CoV-2 spike trimers are presented per nanoparticle. Methods: Here, we describe the CGMP processes for manufacturing SpFN using transient transfection of Expi293F cells. Results: The final yield of SpFN was ~10 mg per liter of media supernatant. The resulting protein is stable in cold storage for two years at −20 °C, as well as for a month at room temperature, and can withstand multiple freeze/thaw cycles. SpFN material produced using the CGMP protocols adjuvanted with Army Liposomal Formulation-QS-21 (ALFQ) elicited potent neutralizing antibodies against WA-1, Alpha, Beta, and Delta variants in mice as measured by a pseudovirus neutralization assay. Conclusions: This work demonstrates rapid development and scaled-up production of clinical-grade SARS-CoV-2 vaccine protein material, allowing permissive storage and transport conditions, and serves as a framework for recombinant protein production for future emergent pathogens.
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(This article belongs to the Special Issue Advances in the Use of Nanoparticles for Vaccine Platform Development: 2nd Edition)
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Strengthening Primary Health Care Through Implementation Research: Strategies for Reaching Zero-Dose Children in Low- and Middle-Income Countries’ Immunization Programs
by
Boniface Oyugi, Karin Kallander and A. S. M. Shahabuddin
Vaccines 2025, 13(10), 1040; https://doi.org/10.3390/vaccines13101040 - 9 Oct 2025
Abstract
Introduction: Despite global improvements in immunization, major gaps persist. By 2024, an estimated 14.3 million infants, predominantly in low- and middle-income countries (LMICs), remained zero-dose (ZD), never having received even the first DTP vaccine. In 2022, 33 million children missed their measles vaccination
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Introduction: Despite global improvements in immunization, major gaps persist. By 2024, an estimated 14.3 million infants, predominantly in low- and middle-income countries (LMICs), remained zero-dose (ZD), never having received even the first DTP vaccine. In 2022, 33 million children missed their measles vaccination (22 million missed the first dose, 11 million missed the second dose), highlighting entrenched structural, behavioral, and systemic barriers that continue to exclude marginalized populations. Addressing these inequities requires innovative, context-adapted approaches that strengthen primary health care (PHC) and extend services to the hardest-to-reach populations. Objectives: This study aims to document and synthesize implementation research (IR) projects on immunization programs in LMICs, identifying key enablers and effective strategies that reduce inequities, improve outcomes, and support efforts to reach ZD children. Methods: We conducted a retrospective multiple-case study of 36 IR projects across 13 LMICs, embedded within an evidence review framework and complemented by policy analysis. Data were drawn from systematic document reviews and validation discussions with project leads. A total of 326 strategies were extracted, coded using a structured codebook, and mapped to the WHO–UNICEF PHC Levers for Action. Descriptive analysis synthesized patterns across service delivery and policy outcomes, including coverage gains, improved microplanning, community engagement, and system integration. Results: Of the 326 immunization strategies identified, most (76.1%) aligned with operational PHC levers, particularly monitoring and evaluation (19.3%), workforce development (18.7%), and models of care (12%). Digital technologies (11.7%) were increasingly deployed for real-time tracking and oversight. Core strategic levers comprised 23.9% of strategies, with community engagement (8.9%) and governance frameworks (7.7%) emerging as critical enablers, though sustainable financing (4%) and private-sector engagement (0.9%) were rarely addressed. While the majority of projects focused on routine immunization (n = 32), only a few directly targeted ZD children (n = 3). Interventions yielded improvements in both service delivery and policy outcomes. Improvements in microplanning and data systems (23.5%) reflected the increased uptake of digital dashboards, GIS-enabled tools, and electronic registries. Community engagement (16.2%) emphasized the influence of local leaders and volunteers in building trust, while health system strengthening (15.7%) invested in cold chain, supervision, and workforce capacity. Coverage gains (10.6%) were achieved through delivery innovations, though sustainable financing remained a critical problem (3.4%). Conclusions: Reaching ZD children requires equity-driven strategies that combine digital innovations, community engagement, and resilient system planning. Sustained progress depends on strengthening governance, financing, and research. Embedding IR in immunization programs generates actionable evidence, supports context-specific strategies, and reduces equity gaps, offering practical insights that complement health system research and advance the Immunization Agenda 2030.
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(This article belongs to the Special Issue Inequality in Immunization 2025)
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Open AccessArticle
A Single Dose of Live-Attenuated Rift Valley Fever Virus Vector Expressing Peste Des Petits Ruminants Virus (PPRV) H or F Antigens Induces Immunity in Sheep
by
Sandra Moreno, Gema Lorenzo, Verónica Martín, Celia Alonso, Friedemann Weber, Belén Borrego and Alejandro Brun
Vaccines 2025, 13(10), 1039; https://doi.org/10.3390/vaccines13101039 - 9 Oct 2025
Abstract
Introduction/Background: Rift Valley fever virus (RVFV) and peste des petits ruminants virus (PPRV) are significant pathogens affecting small ruminants, causing substantial economic losses in the affected regions. The development of effective vaccines against both viruses is crucial for disease control. Recombinant viruses expressing
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Introduction/Background: Rift Valley fever virus (RVFV) and peste des petits ruminants virus (PPRV) are significant pathogens affecting small ruminants, causing substantial economic losses in the affected regions. The development of effective vaccines against both viruses is crucial for disease control. Recombinant viruses expressing heterologous antigens have shown promise as multivalent vaccine candidates. Unlike conventional PPRV vaccines, our recombinant RVFV-vectored vaccines offer a novel dual-protection strategy against RVF and PPR, combining safety, immunogenicity, and a DIVA strategy. Methods: Recombinant RVFVs (ZH548 strain) were generated to express either the hemagglutinin (H) or fusion (F) proteins from the PPRV strain Nigeria 75/1. The stability of these recombinant viruses was assessed through consecutive passages in cell culture. Immunogenicity studies were carried out in both mice and sheep to assess the induction of cellular and humoral immune responses capable of providing protection against RVFV and PPRV. These studies included intracellular cytokine staining (ICS), IFN-γ ELISAs, standard ELISAs for antibody detection, and virus neutralization assays. Results: The recombinant RVFVs expressing PPRV H or F proteins demonstrated stability in cell culture, maintaining high viral titers and consistent transgene expression over four passages. Immunization of mice resulted in the production of serum antibodies capable of neutralizing both RVFV and PPRV in vitro as well as cell-mediated immune responses specific to PPRV and RVFV antigens. In mice vaccinated with a high dose (105 pfu), RVFV neutralizing titers reached ≥1:160 and PPRV neutralizing titers ranged from 1:40 to 1:80 by day 30 post-immunization. In sheep, neutralizing antibody titers against RVFV exceeded 1:160 as early as 2 days post-inoculation, while PPRV-specific neutralization titers reached up to 1:80 by day 21 in responsive individuals. In mice, administration of rZH548ΔNSs:FPPRV elicited a detectable CD8+ IFNγ+ T-cell response against PPRV, with levels ranging from 1.29% to 1.56% for the low and high doses, respectively. In sheep, rZH548ΔNSs:FPPRV also induced a robust IFNγ production against PPRV at 14 and 21 days post-infection (dpi). Conclusions: The successful generation and characterization of recombinant RVFVs expressing PPRV antigens demonstrate the potential of using rationally attenuated RVFV as a vector for multivalent vaccine development. Notably, the strategy proved more effective for the recombinant virus expressing the F protein, as it consistently induced more robust cellular and humoral immune responses. These results suggest that this approach could be a viable strategy for simultaneous immunization against Rift Valley fever and other prevalent ruminant diseases, such as peste des petits ruminants. Even though challenge studies were not performed in target species, the strong immune response observed supports including them in future studies.
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(This article belongs to the Special Issue Next-Generation Vaccines for Animal Infectious Diseases)
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Open AccessReview
Japanese Encephalitis Vaccine in Low- and Middle-Income Countries (LMICs): A Narrative Review of Efficacy, Effectiveness, Safety, Cost, and Policy
by
Eufrasia Ine Pilihanto, Btari Kalisha Nyratri, Muhammad Dafrizal Firdaus and Rano Kurnia Sinuraya
Vaccines 2025, 13(10), 1038; https://doi.org/10.3390/vaccines13101038 - 8 Oct 2025
Abstract
Japanese Encephalitis (JE) is a mosquito-borne viral infection that causes acute brain inflammation. First identified in Japan in 1871, the disease gained renewed global attention in 2025 after emerging in a non-endemic region, raising significant healthcare concerns. Vaccination remains the most effective strategy
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Japanese Encephalitis (JE) is a mosquito-borne viral infection that causes acute brain inflammation. First identified in Japan in 1871, the disease gained renewed global attention in 2025 after emerging in a non-endemic region, raising significant healthcare concerns. Vaccination remains the most effective strategy for preventing outbreaks. However, low- and middle-income countries (LMICs) face considerable challenges in implementing vaccination programs due to geographical, economic, and regulatory barriers. Most existing studies on JE vaccines (JEVs) have been conducted in higher-income countries, leaving critical gaps in data on efficacy and safety in LMIC settings. Furthermore, uncertainties surrounding cost-effectiveness make funding decisions more complex. This narrative review evaluates the current evidence on JE vaccination in LMICs, based on a literature search in PubMed and ScienceDirect covering 2005–2025. The review examines vaccine efficacy, safety, cost-effectiveness, and policy implementation. Findings show that JEVs demonstrate high efficacy and strong safety profiles, with mild adverse effects, most commonly fever. The live attenuated SA 14-14-2 vaccine (LAJEV) is particularly cost-effective, offering substantial economic benefits by reducing healthcare expenditures in endemic regions. To ensure sustainability, vaccination programs in LMICs require tailored policies and targeted financial support. Policy frameworks must be adapted to local contexts, enabling focused, effective, and equitable implementation.
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(This article belongs to the Section Vaccines and Public Health)
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Open AccessArticle
SARS-COV-2 Vaccination Response in Non-Domestic Species Housed at the Toronto Zoo
by
Sara Pagliarani, Jaime Tuling, Phuc H. Pham, Alexander Leacy, Pauline Delnatte, Brandon N. Lillie, Nicholas Masters, Jamie Sookhoo, Shawn Babiuk, Sarah K. Wootton and Leonardo Susta
Vaccines 2025, 13(10), 1037; https://doi.org/10.3390/vaccines13101037 - 8 Oct 2025
Abstract
Background: Due to the wide host range of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), vaccination has been recommended for susceptible species in zoological collections, particularly to protect endangered species. The Zoetis® Experimental Mink Coronavirus Vaccine (Subunit) was temporarily authorized
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Background: Due to the wide host range of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), vaccination has been recommended for susceptible species in zoological collections, particularly to protect endangered species. The Zoetis® Experimental Mink Coronavirus Vaccine (Subunit) was temporarily authorized in 2021–2024 for emergency use in North America for this purpose. However, there are limited data regarding its safety or efficacy in non-domestic mammals. The present study was conducted to assess the ability of this vaccine to elicit serum neutralizing titers against SARS-CoV-2 in selected animals from the Toronto Zoo (TZ) vaccinated during 2022. Methods: Serum samples were collected from 24 individuals across four families (Cervidae, Felidae, Ursidae, and Hyaenidae) and tested using a surrogate virus neutralization test (sVNT) and a plaque-reduction neutralization test (PRNT). Results: The results showed that all species developed some neutralizing titers after at least one vaccine dose, except for polar bears, which showed no seroconversion. Felids and hyenas had the highest neutralizing titers, which peaked at 3 and declined between 4 and 6 months after boost. These differences may stem from species-specific immune responses or lack of vaccination protocols tailored to individual species. Conclusions: While natural infection with SARS-CoV-2 could not be ruled out in the cohort of this study, insights from our results have the potential to inform future vaccine recommendations for non-domestic species. Furthermore, our study highlighted the value of competitive assays in assessing serological responses across a broad range of exotic species, for which reagents, such as anti-isotype antibodies, are often unavailable.
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(This article belongs to the Collection COVID-19 Vaccine Development and Vaccination)
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Safety Evaluation of Tetanus, Diphtheria, and Acellular Pertussis Vaccine (Tdap) During Pregnancy Among Vietnamese Women
by
Hien Minh Nguyen, Nhat Thang Tran, Quoc Huy Pham and Huu Nghia Cao
Vaccines 2025, 13(10), 1036; https://doi.org/10.3390/vaccines13101036 - 8 Oct 2025
Abstract
Background: In Vietnam, the Ministry of Health recently approved the use of Tdap vaccines—Boostrix (2022) and Adacel (2024)—for administration during pregnancy, aiming to provide passive antibody transfer to protect newborns against pertussis and tetanus from birth. However, uptake remains low, largely because Tdap
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Background: In Vietnam, the Ministry of Health recently approved the use of Tdap vaccines—Boostrix (2022) and Adacel (2024)—for administration during pregnancy, aiming to provide passive antibody transfer to protect newborns against pertussis and tetanus from birth. However, uptake remains low, largely because Tdap is not included in the National Expanded Program on Immunization, vaccine hesitancy persists among obstetricians, and local safety data in pregnancy are limited. Methods: We conducted a prospective cohort study from September 2023 to September 2024 involving 485 pregnant women between 27 and 36 weeks of gestation at two major hospitals in Ho Chi Minh City: University Medical Center and Gia Dinh People’s Hospital. Participants received either Tdap or monovalent tetanus toxoid vaccine (TT) as a comparator. Results: Among women in the Tdap group, 49.8% reported at least one adverse event following immunization (AEFI). Local reactions were the most frequent, primarily injection-site pain (43.8%). Fatigue (12.8%) was the most common systemic reaction, followed by headache (3.9%). Grade 3 AEFIs occurred in 5% of the Tdap group and included extensive local reactions (erythema or swelling > 3 cm), high-grade fever (≥40 °C), and severe fatigue interfering with daily activities or requiring hospitalization. Women receiving Tdap had 1.52-fold higher injection-site pain compared with those receiving TT (95% CI: 0.060–0.782). Importantly, co-administration of Tdap with inactivated quadrivalent influenza vaccine (IIV4) did not increase the risk of AEFIs. Furthermore, no evidence was found that Tdap vaccination adversely affected the course of pre-existing maternal comorbidities, which remained stable throughout pregnancy. Conclusions: This first large-scale Vietnamese cohort provides reassuring evidence on the safety of Tdap vaccination during pregnancy. These findings support broader implementation of maternal Tdap immunization, including concomitant administration with IIV4, to protect both mothers and infants.
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(This article belongs to the Special Issue Vaccines for the Vulnerable Population)
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