Vaccines

14 pages, 506 KB

Open AccessArticle

Protection and Duration of 23-Valent Pneumococcal Polysaccharide Vaccine Against Hospitalization for Community-Acquired Pneumonia in Older Adults with Low Vaccination Coverage: A Multicenter Matched Case–Control Study in China

by Tianchi Yang, Xingqiu Ying, Xiaoqing Wu, Junzhe Shao, Lixia Ye and Yumin Tao

Vaccines 2026, 14(7), 646; https://doi.org/10.3390/vaccines14070646 - 22 Jul 2026

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Abstract

Background/Objectives: 23-valent pneumococcal polysaccharide vaccine (PPV23) effectiveness against community-acquired pneumonia (CAP) remains controversial, with critical gaps in low-coverage settings and beyond 5 years post-vaccination. We estimated real-world PPV23 effectiveness against CAP hospitalization and characterized its duration among elderly adults in a low-coverage [...] Read more.

Background/Objectives: 23-valent pneumococcal polysaccharide vaccine (PPV23) effectiveness against community-acquired pneumonia (CAP) remains controversial, with critical gaps in low-coverage settings and beyond 5 years post-vaccination. We estimated real-world PPV23 effectiveness against CAP hospitalization and characterized its duration among elderly adults in a low-coverage region. Methods: A multicenter matched case–control study was conducted across 14 hospitals in Eastern China (2018–2022). Cases were patients aged ≥60 years hospitalized with clinically diagnosed CAP. Up to three controls per case were matched on sex, age (±3 years), admission date (±5 days), hospital, and residential community. Conditional logistic regression estimated vaccine effectiveness (VE), adjusting for chronic comorbidities and healthcare utilization. Results: Among 6645 cases and 15,806 controls, 5-year PPV23 coverage was 2.14% (cases) and 2.76% (controls). PPV23 was associated with a 22.5% reduction in CAP hospitalization (adjusted VE = 22.5%, 95% CI: 4.1% to 37.3%). Protection was concentrated in non-severe CAP (adjusted VE = 25.7%, 95% CI: 7.0% to 40.7%), with no significant effect in severe CAP (adjusted VE = −11.7%, 95% CI: −115.1% to 42.0%). Extending the exposure window to 6 years yielded no significant VE (adjusted VE = 17.3%, 95% CI: −1.8% to 32.8%). Conclusions: PPV23 provides meaningful protection against CAP hospitalization in elderly adults in low-coverage settings, only for non-severe disease. Waning efficacy beyond 5 years supports revaccination at that interval. Full article

(This article belongs to the Special Issue Epidemiology and Real-World Evidence to Inform Vaccine Design, De-Risk Development, and Maximize Real-World Impact)

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18 pages, 283 KB

Open AccessArticle

Influenza Vaccination Status and Associated Factors Among Older Adults in Suzhou, China: A Comparative Cross-Sectional Survey

by Ningning Du, Shuai Shao, Yuanyuan Zhang, Cheng Liu, Yuanyuan Pang, Hui Hang and Liling Chen

Vaccines 2026, 14(7), 645; https://doi.org/10.3390/vaccines14070645 - 22 Jul 2026

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Abstract

Background: Influenza poses a serious threat to the health of older adults, and vaccination is a key strategy for prevention. As an economically developed city, Suzhou has a rapidly aging population, yet the influenza vaccination rate among older adults remains substantially lower than [...] Read more.

Background: Influenza poses a serious threat to the health of older adults, and vaccination is a key strategy for prevention. As an economically developed city, Suzhou has a rapidly aging population, yet the influenza vaccination rate among older adults remains substantially lower than that in developed countries. There is an urgent need to understand the current vaccination status and its associated factors to inform future strategies for improving vaccination coverage. Objectives: To compare influenza- and vaccine-related knowledge, attitudes, practices, and information access channels between vaccinated and unvaccinated older adults (≥60 years) in Suzhou, and to identify factors associated with vaccination behavior in economically developed areas. Methods: A comparative cross-sectional survey was conducted from April to August 2024 across six districts or county-level cities randomly selected from Suzhou’s ten county-level administrative divisions. Participants were divided into vaccinated and unvaccinated groups based on their influenza vaccination status during the 2023–2024 influenza season. A two-stage sampling method was employed: the six districts were selected as primary sampling units; within each district, eligible older adults (aged ≥60 years) were randomly selected from two independent sampling frames—the vaccination information system for the vaccinated group and the basic public health service system for the unvaccinated group. Face-to-face structured interviews were conducted using a questionnaire consisting of four sections; data were entered using EpiData 13.1 and analyzed using SPSS 27.0. The χ² test, t-test, and multivariable logistic regression were used for statistical analysis. Results: Among 4622 valid older adults (vaccinated: n = 2007; unvaccinated: n = 2615), the vaccinated group scored significantly higher on influenza-related knowledge (4.06 ± 2.21 vs. 3.16 ± 2.33, p < 0.001), vaccine-related knowledge (2.10 ± 1.18 vs. 0.67 ± 1.07, p < 0.001), and perceived influenza risk scores (2.72 ± 1.42 vs. 2.26 ± 1.64, p < 0.001). Vaccine safety and efficacy endorsement were also markedly higher among the vaccinated group (70.3% vs. 22.0%; 49.7% vs. 9.3%). Regarding information sources, the vaccinated group relied more on healthcare institutions (54.56% vs. 46.92%), whereas the unvaccinated group relied more on television (60.34% vs. 51.17%). Multivariable logistic regression revealed that awareness of the influenza vaccine (aOR = 9.151, 95%CI: 6.32–13.25), having a planned vaccination site (aOR = 2.66, 95%CI: 2.01–3.54), and perceiving the vaccine as safe (aOR = 1.81, 95%CI: 1.31–2.49) were positively associated with vaccination, while rural household registration (aOR = 0.76, 95%CI: 0.63–0.93), full-time employment (aOR = 0.41, 95%CI: 0.28–0.60), and hypertension (aOR = 0.79, 95%CI: 0.65–0.94) were inversely associated. Conclusions: Compared with the unvaccinated group, the vaccinated group demonstrated significantly better influenza- and vaccine-related knowledge, risk perception, and recognition of vaccine safety and efficacy, and relied more on healthcare institutions for information. Multivariable regression analysis identified awareness of the influenza vaccine as the strongest associated factor. These findings suggest that vaccination coverage could be improved by strengthening vaccine knowledge promotion through healthcare professionals and increasing awareness of vaccination policies that integrate medical insurance reimbursement. Full article

(This article belongs to the Section Vaccines and Public Health)

23 pages, 1841 KB

Open AccessArticle

Site-Specific Glycosylation Profiling of Protein Subunit and Inactivated Virus Vaccines

by Zachary C. Goecker, Meghan C. Burke, Yi Liu, Yuri A. Mirokhin, Sergey L. Sheetlin, Guanghui Wang, Dmitrii V. Tchekhovskoi, Xiaoyu Yang and Stephen E. Stein

Vaccines 2026, 14(7), 644; https://doi.org/10.3390/vaccines14070644 - 22 Jul 2026

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Abstract

Background/Objectives: Glycosylation can affect vaccine antigen structure and function, making site-specific glycan characterization relevant to antigen quality and comparability. However, quantitative approaches for comparing glycan microheterogeneity remain limited. This study evaluated the utility of the glycopeptide abundance distribution spectra framework for measuring [...] Read more.

Background/Objectives: Glycosylation can affect vaccine antigen structure and function, making site-specific glycan characterization relevant to antigen quality and comparability. However, quantitative approaches for comparing glycan microheterogeneity remain limited. This study evaluated the utility of the glycopeptide abundance distribution spectra framework for measuring similarity among site-specific glycosylation profiles in vaccines and antigen reference reagents across manufacturing conditions. Methods: Intact N-linked glycopeptides were characterized by nanoflow liquid chromatography–tandem mass spectrometry with stepped-energy fragmentation. Products included monovalent and quadrivalent influenza antigens produced in embryonated eggs, Madin–Darby canine kidney cells, or Spodoptera frugiperda cells, together with a SARS-CoV-2 spike vaccine produced in Spodoptera frugiperda cells and a Chinese hamster ovary cell-produced varicella-zoster virus glycoprotein E vaccine. Site-specific glycan distributions were represented as distribution spectra and compared using NIST MS Search software. Dot-product scores ranging from 0 to 999 quantified similarity. Results: Across measured glycosylation sites, distributions clustered into six recurrent classes. Similarity was high for replicate analyses, conserved influenza components across annual formulations, and matched components from different suppliers within the same production platform (similarity scores = 978, 961, and 960, respectively). Similarity was lower between sites within the same protein, between influenza strains, and between production sources (similarity scores = 554, 540, and 209, respectively). Among production-source comparisons, egg- and Madin–Darby canine kidney-derived profiles were most similar, and the overall ordering of glycosylation similarity was consistent with broad phylogenetic relatedness among production hosts. Conclusions: Distribution spectra-based similarity scoring of vaccine glycoproteins provides a quantitative, reusable approach for documenting site-specific glycosylation microheterogeneity. Using this method, we can conclude that production source is the dominant contributor to variation, whereas replicates, annual formulations, and suppliers within the same production platform are highly consistent. Full article

(This article belongs to the Section Vaccine Design, Development, and Delivery)

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16 pages, 400 KB

Open AccessArticle

Preventive Strategies and Determinants of Vaccination Compliance Among Older Adults in Rural Amazonian Communities

by Luciana T. Pasquel-Muñoz, Ana Lucía Ramírez-Béjar, Joaquín Eduardo Chávez Cano, Kiara Camacho-Caballero, José F. Parodi and Fernando M. Runzer-Colmenares

Vaccines 2026, 14(7), 643; https://doi.org/10.3390/vaccines14070643 - 22 Jul 2026

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Abstract

Background/Objectives: Respiratory infections are a major cause of morbidity and mortality among older adults. However, vaccination coverage against respiratory pathogens remains suboptimal, particularly in rural and vulnerable populations. This study aimed to identify factors associated with respiratory vaccination uptake among older adults living [...] Read more.

Background/Objectives: Respiratory infections are a major cause of morbidity and mortality among older adults. However, vaccination coverage against respiratory pathogens remains suboptimal, particularly in rural and vulnerable populations. This study aimed to identify factors associated with respiratory vaccination uptake among older adults living in rural Amazonian communities in Peru. Methods: We conducted an observational, analytical, cross-sectional study using secondary data from the Amazon Frail Project. A total of 429 adults aged ≥60 years from rural and suburban communities in San Martín, Loreto, and Ucayali were included. Vaccination coverage for influenza, pneumococcal disease, pertussis, and COVID-19, as well as vaccine combinations, was assessed. Multiple linear and Poisson regression models with robust variance were used to identify associated factors. Results: Complete vaccination coverage was 42.89% for influenza, 23.08% for pneumococcal disease, 4.43% for pertussis, and 70.16% for COVID-19. Only 3.50% of participants had received all four respiratory vaccines. Higher educational attainment, multimorbidity, social frailty, greater muscle mass, better physical performance, and healthcare center attendance were associated with higher vaccination uptake. Depressive symptoms, cognitive impairment, functional dependency, physical frailty, dynapenia, and higher body mass index were associated with lower vaccination uptake. Conclusions: Respiratory vaccination coverage was suboptimal among older adults living in rural Amazonian communities. Educational, functional, physical, social, and healthcare access factors significantly influenced vaccine uptake, highlighting the need for targeted immunization strategies in vulnerable rural populations. Full article

(This article belongs to the Special Issue Vaccination and Public Health in the 21st Century, 2nd Edition)

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14 pages, 4221 KB

Open AccessArticle

Inactivation of Wild Poliovirus with β-Propiolactone

by Anastasia Kovpak, Sergey Pashkov, Mariia Kostrova, Kirill Nebesnyi, Nikita Yakovlev, Olga Polyakova, Vladislav Vasilenko, Lycheva Natalia, Yury Ivin, Anastasia Piniaeva, Alexandra Siniugina and Aydar Ishmukhametov

Vaccines 2026, 14(7), 642; https://doi.org/10.3390/vaccines14070642 - 21 Jul 2026

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Abstract

Objectives: Antiviral vaccines are usually created by inactivating viruses using physical or chemical methods. Inactivation of poliovirus with β-propiolactone (BPL) has advantages, including the absence of a requirement for long-term incubation with the inactivating agent, which minimizes the risk of negative effects of [...] Read more.

Objectives: Antiviral vaccines are usually created by inactivating viruses using physical or chemical methods. Inactivation of poliovirus with β-propiolactone (BPL) has advantages, including the absence of a requirement for long-term incubation with the inactivating agent, which minimizes the risk of negative effects of the potentially dangerous substance on the virus and reduces the duration of the inactivation process. Methods: BPL was applied at 0.2% (w/v) concentration under two conditions: 4 °C for 24 h and 37 °C for 3 h. Inactivation completeness was confirmed on Vero cell culture, while immunogenicity was assessed in guinea pigs via neutralizing antibody test. Conclusions: Two variants of virus inactivation made it possible to obtain inactivated samples that retained their immunogenic properties. BPL-inactivated samples retained sufficient D-antigen levels and elicited neutralizing antibodies comparable to or exceeding those from formaldehyde-inactivated controls. The inactivation method at 37 °C provided faster inactivation, while at 4 °C it provided a smooth decrease in virus titer. These results confirm that β-propiolactone is a viable alternative to formaldehyde for the production of inactivated polio vaccine (IPV), providing rapid inactivation of the virus compared to inactivation with formaldehyde while maintaining immunogenicity, as confirmed by guinea pig control. Full article

(This article belongs to the Special Issue Vaccine Design and Development)

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23 pages, 891 KB

Open AccessReview

GnRH-Based Immunocastration Vaccines: Comparative Analysis and Role in Boar Taint Reduction

by Jisang Kim, Mariusz Skwarczynski and Rachel J. Stephenson

Vaccines 2026, 14(7), 641; https://doi.org/10.3390/vaccines14070641 - 21 Jul 2026

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Abstract

Boar taint is a persistent challenge in pork production, caused primarily by the accumulation of androstenone and skatole in adipose tissue. It affects 5–40% of uncastrated male pigs and is perceived negatively by a substantial proportion of consumers, with skatole detectable by almost [...] Read more.

Boar taint is a persistent challenge in pork production, caused primarily by the accumulation of androstenone and skatole in adipose tissue. It affects 5–40% of uncastrated male pigs and is perceived negatively by a substantial proportion of consumers, with skatole detectable by almost all individuals. Traditional surgical castration effectively prevents boar taint but is increasingly criticized on animal welfare grounds. Immunocastration using gonadotropin-releasing hormone (GnRH) vaccines has emerged as a promising alternative, providing reversible suppression of reproductive function while maintaining growth efficiency. This review integrates current knowledge on the biochemical basis of boar taint, evaluates the performance of commercial vaccines such as Improvac^® and GonaCon^®, and examines economic, regulatory, and consumer factors influencing adoption. Immunocastration presents limitations due to variability in immune responses, the need for multiple doses, and challenges related to public perception. To address these challenges, intensive research is underway on single-dose formulations, precision adjuvants, and advanced delivery technologies, all of which are expected to drive the next generation of immunocastration vaccines. Full article

(This article belongs to the Section Veterinary Vaccines)

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19 pages, 5340 KB

Open AccessArticle

Immunogenicity of a Candidate Hepatitis C Vaccine Based on Non-Structural DNA-Protein Sequences and a Novel Complex Adjuvant

by Olga V. Masalova, Ekaterina I. Lesnova, Vyacheslav V. Kozlov, Vladimir T. Valuev-Elliston, Kristina Yu. Permyakova, Natalya E. Fedorova, Tatyana N. Nikolaeva, Alexander V. Pronin, Alexander V. Ivanov and Alla A. Kushch

Vaccines 2026, 14(7), 640; https://doi.org/10.3390/vaccines14070640 - 21 Jul 2026

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Abstract

Global elimination of hepatitis C virus (HCV) infection requires not only direct-acting antivirals (DAAs) but also the development of a highly effective prophylactic and/or therapeutic vaccine. Background/Objectives: Our aim was to optimize the composition of the candidate vaccine against HCV by combining [...] Read more.

Global elimination of hepatitis C virus (HCV) infection requires not only direct-acting antivirals (DAAs) but also the development of a highly effective prophylactic and/or therapeutic vaccine. Background/Objectives: Our aim was to optimize the composition of the candidate vaccine against HCV by combining recombinant non-structural proteins and a DNA construct with a complex adjuvant. Methods: C57BL/6 and DBA/2J mice were immunized three times at 2-week intervals using different schemes. The viral antigens consisted of a mixture of NS3, NS5A, and NS5B proteins and/or recombinant DNA expressing NS3-NS5B polyprotein. As adjuvants, a complex adjuvant, a mixture of Polymuramil^® and Pyrogenalum^® (NOD1/NOD2 and TLR-4 agonists), or a CpG ODN adjuvant (TLR-9 agonist) were used. Results: The most efficient regimen was three subcutaneous administrations of the combined DNA, recombinant protein components, and a new complex adjuvant. This scheme elicited a robust immune response, characterized by high antibody titers, enhanced antigen-specific lymphocyte proliferation, and significant interferon-gamma (IFN-γ) secretion in both mouse lines. Furthermore, the complex adjuvant outperformed CpG ODN in stimulating both humoral and cellular immunity against the HCV antigens. The vaccine composition stimulated the formation of CD4⁺ memory T cells and decreased the relative frequences of suppressive Treg and MDSCs. Conclusions: The presented candidate vaccine induces a strong immune response to HCV proteins. The next step would be to validate the protective effect in cell culture and animal models. This would one the path to preclinical studies of this vaccine composition. Full article

(This article belongs to the Special Issue Chronic Viral Infections and Cancer: Openings for Vaccines and Cure)

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5 pages, 189 KB

Open AccessEditorial

Challenges and Future Perspectives for Vaccines Targeting the Tumor Microenvironment

by Devin B. Lowe, Neda Feizi and Walter J. Storkus

Vaccines 2026, 14(7), 639; https://doi.org/10.3390/vaccines14070639 - 21 Jul 2026

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Abstract

Immunotherapies integrating immune checkpoint inhibitors (ICI) represent the current standard of care for many solid cancers, yet they effectively treat only a minority of patients due to intrinsic or acquired resistance mechanisms [...] Full article

(This article belongs to the Special Issue Vaccines Targeting the Tumor Microenvironment: Challenges and Future Prospects)

18 pages, 649 KB

Open AccessArticle

Immunization Gaps Among High-Risk Preterm Infants in Kazakhstan

by Balzhan N. Tatibekova, Daniel Yakubovich, Ademi K. Sagatbayeva and Aigul A. Ismailova

Vaccines 2026, 14(7), 638; https://doi.org/10.3390/vaccines14070638 - 20 Jul 2026

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Abstract

Background: Advances in neonatal intensive care in Kazakhstan have improved the survival of preterm infants, including those with very low birth weight (VLBW) and extremely low birth weight (ELBW). However, after hospital discharge, these medically vulnerable children may remain insufficiently protected against vaccine-preventable [...] Read more.

Background: Advances in neonatal intensive care in Kazakhstan have improved the survival of preterm infants, including those with very low birth weight (VLBW) and extremely low birth weight (ELBW). However, after hospital discharge, these medically vulnerable children may remain insufficiently protected against vaccine-preventable infections because of prolonged temporary medical exemptions, clinical caution, parental concerns, and fragmented coordination between specialized follow-up services and primary health care. Objective: This study aimed to assess vaccination coverage in a 10-year cohort of high-risk preterm infants and to identify clinical, parental, and organizational factors associated with delayed immunization. Methods: We conducted a retrospective cohort study of 331 high-risk preterm infants followed at a specialized pediatric center in Astana, Kazakhstan, between 2015 and 2024. Vaccination status at hospital discharge and at 24 months of chronological age, documented temporary medical exemptions, reasons for delayed or missed vaccination, and confirmed cases of pertussis and measles were analyzed. A supplementary cross-sectional survey of parents, physicians, and health care managers was conducted to further explore barriers to catch-up immunization. Results: At hospital discharge, 259 infants (78.2%) had not received the BCG or hepatitis B vaccine. By 24 months of age, 34.1% (n = 113) were fully vaccinated according to age, whereas 49.8% (n = 165) remained completely unvaccinated. During the observation period, 30 cases of measles and 17 cases of pertussis were recorded within the cohort, primarily during nationwide outbreaks. Among the 10 children with a history of measles before 12 months of age, 2 developed subacute sclerosing panencephalitis (SSPE), 1 developed profound hearing loss, and 1 required prolonged oxygen therapy following pneumonia. In addition, 2 children with periventricular leukomalacia (PVL) experienced clinical deterioration, while 1 infant with pertussis required hospitalization during the acute phase of illness. Conclusion: High-risk preterm infants in this cohort experienced substantial and persistent gaps in immunization after hospital discharge. These findings underscore the importance of regular reassessment of temporary medical exemptions, improved coordination between specialized follow-up services and primary health care, and strengthened catch-up immunization strategies for medically vulnerable children. Full article

(This article belongs to the Special Issue Advancing Health: Vaccination and Infectious Disease Prevention in Pregnant Women, Neonates, Infants, and Children)

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15 pages, 272 KB

Open AccessFeature PaperArticle

Vaccination Coverage Among Mothers and Close Contacts of Neonates Hospitalized in NICU in Southern Greece: A Cocooning Strategy Approach

by Angeliki Irakleous, Eleni Vergadi, Despoina Gkentzi and Eleftheria Hatzidaki

Vaccines 2026, 14(7), 637; https://doi.org/10.3390/vaccines14070637 - 20 Jul 2026

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Abstract

Background: Neonates and young infants are susceptible to vaccine-preventable diseases because of immature immune responses and delayed acquisition of vaccine-induced protection. As household members and caregivers are a major source of exposure, international organizations recommend cocooning, i.e., vaccination of susceptible individuals who are [...] Read more.

Background: Neonates and young infants are susceptible to vaccine-preventable diseases because of immature immune responses and delayed acquisition of vaccine-induced protection. As household members and caregivers are a major source of exposure, international organizations recommend cocooning, i.e., vaccination of susceptible individuals who are in regular contact with infants, to provide complementary indirect neonatal protection. To evaluate cocooning implementation, we assessed influenza and pertussis vaccination uptake among mothers and close contacts of hospitalized neonates and identified factors associated with vaccine uptake. Methods: Mothers of neonates hospitalized in a Neonatal Intensive Care Unit (NICU) between 1 January 2022 and 31 December 2024 were invited to complete a structured questionnaire. Mothers reported their own vaccination status and that of the neonate’s close contacts. Associations between maternal characteristics and vaccine uptake were examined using logistic regression. Results: In total, 405 mothers participated. Influenza vaccination uptake was 47.6% among mothers, and at least one adult close contact was vaccinated in 53.6% of families. Pertussis vaccination uptake was 40.5% among mothers, and at least one adult close contact was vaccinated in 32.3% of families. The most frequently reported reason for non-vaccination was low perceived need among unvaccinated mothers (74.1% for influenza and 83.4% for pertussis) and among families with incompletely vaccinated adult close contacts (81.8% for influenza and 89.7% for pertussis). In multivariable analyses, higher maternal education was associated with increased uptake of both influenza (OR 2.36, 95% CI: 1.47–3.80, p < 0.001) and pertussis vaccination (OR 4.25, 95% CI 2.02–8.94, p < 0.001), whereas younger maternal age (≤25 years) was associated with lower influenza vaccine acceptance (OR 0.24, 95% Cl: 0.1–0.60, p = 0.002). Conclusions: Vaccination uptake among mothers and adult close contacts of NICU-admitted neonates was suboptimal for both influenza and pertussis vaccines. Targeted counseling before delivery, reinforced during maternity or NICU hospitalization as a catch-up opportunity, and system-level implementation measures aligned with the dominant barrier of low perceived need are needed to strengthen cocooning in this high-risk population. Full article

(This article belongs to the Special Issue Vaccination in Pregnancy and Early Life: Evidence, Challenges, and Innovations)

14 pages, 1725 KB

Open AccessArticle

Impact of Enhanced Outreach Activities on Immunization Coverage in Pakistan: Evidence from Secondary Data Analysis (2011–2021)

by Shah Nawaz Jiskani, Musa Khan, Mohammed Osama Mere, Wei Xia and Atta Ur Rehman

Vaccines 2026, 14(7), 636; https://doi.org/10.3390/vaccines14070636 - 20 Jul 2026

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Abstract

Background: Despite noteworthy progress in the Expanded Program on Immunization (EPI) for improving vaccination coverage worldwide, inequalities in vaccine uptake and accessibility persist in several middle- and low-income states. Pakistan’s routine vaccination uptake varies greatly between federal geographical regions and continues to fall [...] Read more.

Background: Despite noteworthy progress in the Expanded Program on Immunization (EPI) for improving vaccination coverage worldwide, inequalities in vaccine uptake and accessibility persist in several middle- and low-income states. Pakistan’s routine vaccination uptake varies greatly between federal geographical regions and continues to fall below the standard threshold needed to attain optimal herd immunity. The Federal Directorate of Immunization (FDI) in collaboration with the provincial Expanded Program on Immunizations implemented Enhanced Outreach Activities (EOAs) to boost immunization delivery in selected districts in order to address immunization coverage gaps in marginalized and difficult-to-reach communities. The purpose of this secondary data research was to evaluate whether EOAs improved immunization coverage in the country. Methods: The Federal Directorate of Immunization’s longitudinal panel analysis of district–month administrative data for the years 2011–2021 have been analyzed. The research investigation reviewed 158 districts’ monthly vaccination records for multiple antigens, covering regions where EOAs were successfully carried out in particular months. National and subnational analyses were carried out to measure geographical variations in the impact of Enhanced Outreach Activities (EOAs). The average vaccination coverage during EOAs and non-EOAs months was compared using the paired t-test. Results: An aggregate of 2430 months with EOAs were included in the analysis of 19,068 monthly district observations. National level analysis revealed higher average vaccinations during the EOA months for all antigens, but a statistically significant increase was observed for IPV and measles second dose (p < 0.05) only. Provincial-level results indicate that the impact was more evident in underserved regions. Khyber Pakhtunkhwa, Balochistan, Punjab, and Sindh demonstrated statistically significant increases in vaccination counts for most antigens. Due to variations in baseline population coverage, as well as health care sector capability, the extent of improvements differed throughout regions. Conclusions: In Pakistan, routine immunization counts has been improved via enhanced outreach initiatives, especially in provinces with lower initial vaccination rates and restricted accessibility to services. Strengthening outreach strategies, together with consistent fixed-site immunization services, is likely to accelerate progress toward equitable immunization coverage and contribute to achieving the Immunization Agenda 2030 goals. Full article

(This article belongs to the Special Issue Epidemiology and Real-World Evidence to Inform Vaccine Design, De-Risk Development, and Maximize Real-World Impact)

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21 pages, 2503 KB

Open AccessArticle

A Multi-State, Cross-Sectional Retrospective Study on Knowledge, Attitude and Practice of Rabies Post-Exposure Prophylaxis Including Rabies Monoclonal Antibody Among Physicians Across India

by Ravish Haradanahalli Shankaraiah, Navyashree N. S., Divya Bharathi G., Trayambak Dutta and Manish Mahajan

Vaccines 2026, 14(7), 635; https://doi.org/10.3390/vaccines14070635 - 20 Jul 2026

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Abstract

Background/Objectives: Rabies remains a lethal vaccine-preventable disease in India, and physicians managing animal-bite cases are central to effective post-exposure prophylaxis (PEP). With the increasing use of rabies monoclonal antibodies (RmAbs) as alternatives to conventional rabies immunoglobulins, this study assessed physicians’ knowledge, attitude, and [...] Read more.

Background/Objectives: Rabies remains a lethal vaccine-preventable disease in India, and physicians managing animal-bite cases are central to effective post-exposure prophylaxis (PEP). With the increasing use of rabies monoclonal antibodies (RmAbs) as alternatives to conventional rabies immunoglobulins, this study assessed physicians’ knowledge, attitude, and practice (KAP) regarding rabies PEP, including RmAb awareness and acceptance. Methods: This multi-state, cross-sectional retrospective KAP survey was conducted among 208 physicians across ten Indian states using a structured, self-administered Google Form. The 33-item questionnaire assessed Knowledge, Attitude, and Practice domains, with 11 items each, scored binarily according to NCDC guidelines. Descriptive statistics, Shapiro–Wilk normality testing, Kruskal–Wallis tests with post hoc corrections, and Spearman rank-order correlations were performed. Results: Mean domain scores were 8.00/11 for Knowledge (72.7%), 7.22/11 for Attitude (65.6%), and 8.64/11 for Practice (78.5%). Key gaps were identified in the intramuscular pre-exposure prophylaxis schedule, management of excess RIG/RmAb after wound infiltration, exposure categorization of animal contact, and vaccine administration site in young children. The Knowledge–Practice correlation was moderately strong and statistically significant (r = 0.520, p < 0.001). Acceptance of RmAbs was high, with 88.5% recognizing them as effective replacements for RIGs and 84.6% considering them safer than RIGs. Practice scores showed the most consistent improvement, Knowledge scores improved on most items but declined sharply for the pre-exposure prophylaxis schedule, and Attitude scores showed a mixed pattern of gains and losses compared with the 2013 benchmark survey. Conclusions: Overall KAP scores were adequate, with Practice scoring highest. Targeted continuing medical education focused on NCDC guidelines and practical PEP scenarios is needed among physicians managing rabies exposures. Full article

(This article belongs to the Special Issue Rabies: Prevention, Vaccines, and One Health)

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14 pages, 41292 KB

Open AccessArticle

Recombinant EHV-1 Vector Expressing Immunodominant Hemagglutinin Protein of Equine Influenza Virus H3N8 (Sub-Lineage Florida Clade 2)

by Bidhan Chandra Bera, Manju Bernela, Aashwina Madhwal, Stephanie S. Pradhan, Venkataramireddy Balena, Taruna Anand, Supriya Kandasamy, Selvaraj Pavulraj, Wandit Ahlawat, Diksha Kandpal, Priya Mor, Gurmesh Bishnoi, Nishant Vasdev, Bhupendra Nath Tripathi, Tarun Kumar Bhattacharya and Nitin Virmani

Vaccines 2026, 14(7), 634; https://doi.org/10.3390/vaccines14070634 - 20 Jul 2026

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Abstract

Background: Equine herpesvirus type 1 (EHV-1) and equine influenza virus (EIV) are major respiratory pathogens in horses, causing significant economic losses in domesticated horses. Bacterial Artificial Chromosome (BAC) technology can be used to precisely manipulate the EHV-1 genome for the development of live-attenuated [...] Read more.

Background: Equine herpesvirus type 1 (EHV-1) and equine influenza virus (EIV) are major respiratory pathogens in horses, causing significant economic losses in domesticated horses. Bacterial Artificial Chromosome (BAC) technology can be used to precisely manipulate the EHV-1 genome for the development of live-attenuated vector vaccines. Earlier, our group developed a live-attenuated EHV-1 vaccine by deleting virulence-associated genes using this technology and the mutant EHV-1 has been exploited for expressing foreign gene in the current study. Specifically, in this study, a mutant EHV-1 virus expressing the hemagglutinin (HA) gene of H3N8 EIV (sub-lineage: Florida clade 2) was generated and characterized in vitro. Methods: The HA gene of EIV (Florida clade 2) was used for antigen gene cloning. The expression cassette for the HA gene was commercially synthesized and inserted into the backbone of EHV1∆IR6 BAC using an En passant mutagenesis strategy. Recombinant clones were selected using antibiotic selection, PCR, and RFLP. Further, the recombinant virus was regenerated in RK-13 cells via transfection and characterized in vitro for plaque size, growth kinetics and immunofluorescence antibody test (IFAT). Results: PCR and RFLP confirmed the successful insertion of the HA gene into pEHV1∆IR6/gE BAC. The recombinant virus, vEHV1∆IR6/gE-HA(FC2), was successfully rescued in RK13 cells and demonstrated expression of the EIV haemagglutinin proteins by immunofluorescence assay. Although plaque size was reduced in the generated mutant virus in comparison to parental virus, the growth kinetics of the recombinant viruses were comparable to those of vEHV1∆IR6/gE. Conclusions: These findings demonstrate the successful expression of immunodominant hemagglutinin protein of EIV by recombinant EHV-1 and indicate the potential suitability of EHV-1 BAC as a vector platform for foreign gene expression. Full article

(This article belongs to the Section Influenza Virus Vaccines)

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6 pages, 1297 KB

Open AccessEditorial

Beyond Vaccine Efficacy: Redefining the Next Era of Human Papillomavirus Vaccination

by Luca Giannella and Andrea Ciavattini

Vaccines 2026, 14(7), 633; https://doi.org/10.3390/vaccines14070633 - 20 Jul 2026

Viewed by 315

Abstract

The greatest challenge in human papillomavirus (HPV) vaccination is no longer scientific [...] Full article

(This article belongs to the Special Issue Human Papillomavirus Vaccine Against Cervical Cancer: New Usage Strategies and Coverage Issues)

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24 pages, 2549 KB

Open AccessSystematic Review

Opportunities and Barriers to HPV Vaccination Among Men Who Have Sex with Men and Related Sexual and Gender Minority Populations: A Systematic Review and Exploratory Clustering Analysis Using a Socio-Ecological Framework

by Jiayu Cai, Zhuohang Liu, You Zuo and Yiu Wing KAM

Vaccines 2026, 14(7), 632; https://doi.org/10.3390/vaccines14070632 - 20 Jul 2026

Viewed by 280

Abstract

Background: Men who have sex with men (MSM) experience a disproportionate burden of human papillomavirus (HPV)-related disease, yet vaccination uptake remains uneven. With MSM as the key population of interest, this review synthesized evidence on uptake, willingness, multilevel barriers and opportunities, and [...] Read more.

Background: Men who have sex with men (MSM) experience a disproportionate burden of human papillomavirus (HPV)-related disease, yet vaccination uptake remains uneven. With MSM as the key population of interest, this review synthesized evidence on uptake, willingness, multilevel barriers and opportunities, and vaccine-oriented outcomes among MSM and related sexual and gender minority populations when MSM-relevant findings could be extracted. Methods: Six databases were searched for original English- or Chinese-language studies published from 1 January 2010 to 31 December 2025. Findings were synthesized narratively. Barriers and opportunities were mapped using a five-level socio-ecological model; study-level willingness–uptake patterns were explored using K-means clustering as an exploratory analysis among the nine studies reporting both outcomes; and genotype-specific and immunogenicity findings were summarized separately. Results: Fifty-three studies involving 169,241 participants were included; 87.2% of participants were MSM, and 79% of studies were cross-sectional. Barriers and opportunities occurred across individual, provider-related interpersonal, organizational/institutional, community, and policy/societal levels. Recurrent paired mechanisms involved knowledge and trust, provider recommendation and communication, service accessibility, community support, and eligibility and affordability. Nine studies contributed data to the exploratory clustering analysis; seven fell into low-uptake clusters, including three with high willingness but low uptake, which may indicate a possible study-level implementation gap. Two studies reporting genotype prevalence and antibody responses provided limited biological context supporting vaccination before exposure and suggesting potential benefit from catch-up vaccination. Discussion: Among MSM and related sexual and gender minority populations, HPV vaccination is shaped by interacting individual and structural conditions, with MSM remaining the principal focus of the evidence base. Improving uptake is likely to require complementary strategies: universal, gender-neutral routine vaccination in adolescence before their sexual debut, and targeted catch-up for MSM who missed routine vaccination, supported by trusted provider endorsement, convenient service delivery, community engagement, and inclusive, affordable policy. The thematic counts were study-level and unweighted, and the nine-study clustering analysis was exploratory rather than definitive. Full article

(This article belongs to the Special Issue Vaccination and Public Health in the 21st Century, 2nd Edition)

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10 pages, 834 KB

Open AccessFeature PaperArticle

Influenza Vaccine Effectiveness Against Influenza-like Illness in Post-Operative Children with Congenital Heart Disease: A Retrospective Cohort Study Using Inverse Probability of Treatment Weighting

by Rui Liu, Pengfei Deng, Tian Yang, Yun Pan, Zhuoming Xu, Laibao Yang, Caoyi Xue and Qizhang Wang

Vaccines 2026, 14(7), 631; https://doi.org/10.3390/vaccines14070631 - 20 Jul 2026

Viewed by 303

Abstract

Background: Children with congenital heart disease (CHD) are highly vulnerable to influenza, yet real-world vaccine effectiveness (VE) data in this post-operative population are lacking, especially in China. This study estimated influenza VE against medically attended influenza-like illness (ILI) in post-operative children with [...] Read more.

Background: Children with congenital heart disease (CHD) are highly vulnerable to influenza, yet real-world vaccine effectiveness (VE) data in this post-operative population are lacking, especially in China. This study estimated influenza VE against medically attended influenza-like illness (ILI) in post-operative children with CHD using inverse probability of treatment weighting (IPTW) to address confounding. Methods: We retrospectively enrolled 194 children who underwent CHD surgery in Shanghai (January–July 2023). Vaccination records were obtained from the Shanghai Immunization Information System, and ILI episodes were captured via structured interviews. The primary analysis used doubly robust quasi-Poisson regression on an IPTW pseudo-population. VE = (1 − RR) × 100%. Sensitivity analyses included multivariable Poisson regression, marginal structural models, and stabilized IPTW. Results: Vaccination coverage was 21.6% (42/194). After IPTW, all covariates were well-balanced (SMD < 0.10). The primary VE was 50.9% (95% CI: 11.0–72.9%). Sensitivity estimates ranged from 49.6% to 56.6%. Subgroup analyses showed consistently protective point estimates. Conclusions: Influenza vaccination provided moderate, robust protection (≈51% VE) against ILI in post-operative CHD children, comparable to healthy pediatric populations. Our results reinforce the urgent need to prioritize influenza immunization in this vulnerable group and offer critical baseline data for China. Full article

(This article belongs to the Special Issue Advancements in Vaccine Research: Epidemiology, Immunogenicity, Effectiveness and Safety)

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19 pages, 1248 KB

Open AccessReview

Anthralin—From Psoriasis Drug to Power Adjuvant

by Carolin Michael, Matthias Bros, Markus P. Radsak, Hansjörg Schild and Stephan Grabbe

Vaccines 2026, 14(7), 630; https://doi.org/10.3390/vaccines14070630 - 18 Jul 2026

Viewed by 469

Abstract

Anthralin has a long history as a topical treatment for psoriasis, where it reduces keratinocyte hyper-proliferation and effectively clears plaques. While it lowers inflammatory markers in psoriatic skin, it paradoxically induces inflammation in healthy skin through reactive oxygen species (ROS) and related pathways. [...] Read more.

Anthralin has a long history as a topical treatment for psoriasis, where it reduces keratinocyte hyper-proliferation and effectively clears plaques. While it lowers inflammatory markers in psoriatic skin, it paradoxically induces inflammation in healthy skin through reactive oxygen species (ROS) and related pathways. However, its precise mechanism of action remains incompletely understood. Interestingly, the once undesirable pro-inflammatory effect in healthy skin may now represent a valuable adjuvant property for transcutaneous immunization (TCI). In particular, combining anthralin with the TLR7 agonist imiquimod (IMQ) elicits strong cytotoxic T-cell responses in pre-clinical studies. When paired with antigenic peptides that can penetrate the skin, this immunization approach is especially promising in the context of cancer therapy, given the central role of cytotoxic T-cells in tumor rejection. However, current evidence is largely derived from mouse models, but its efficacy and safety in humans remain to be established. This review therefore examines whether anthralin can be repurposed as a cutaneous adjuvant for transcutaneous immunization, and which mechanistic and translational constraints must be overcome before human application. Full article

(This article belongs to the Section Vaccines, Clinical Advancement, and Associated Immunology)

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20 pages, 3253 KB

Open AccessReview

Vaccine Responses in Early Age

by Swetha Parvathaneni, Jiro Sakai, Lunhua Liu and Mustafa Akkoyunlu

Vaccines 2026, 14(7), 629; https://doi.org/10.3390/vaccines14070629 - 18 Jul 2026

Viewed by 756

Abstract

Neonates and infants exhibit fundamentally distinct immune responses compared to adults, resulting in increased susceptibility to infectious diseases and reduced vaccine efficacy. These age-specific responses are characterized by developmental constraints affecting both adaptive and innate immunity. T cell-independent (TI) responses to polysaccharide vaccines [...] Read more.

Neonates and infants exhibit fundamentally distinct immune responses compared to adults, resulting in increased susceptibility to infectious diseases and reduced vaccine efficacy. These age-specific responses are characterized by developmental constraints affecting both adaptive and innate immunity. T cell-independent (TI) responses to polysaccharide vaccines are severely impaired due to reduced transmembrane activator and calcium-modulating cyclophilin ligand interactor (TACI) expression on neonatal B cells, while T cell-dependent (TD) responses are compromised by Th2 bias in the CD4+ T cell compartment, and by restricted T follicular helper (Tfh) cell development. Emerging data suggest that cytokines such as IL-6 have completely opposite effects on Tfh cell development between adults and neonates. Germinal center (GC) B cell responses are further constrained by delayed follicular dendritic cell (FDC) maturation, impaired B cell receptor (BCR) signaling, and elevated frequencies of IL-10-producing regulatory B cells. The overall immunosuppressive phenotype associated with early age extends to the neonatal innate immune system as exhibited by altered dendritic cell (DC) subset distribution, decreased IL-12p70 production, lower expression of MHC class II and co-stimulatory molecules, and increased IL-10 secretion. To overcome these immune constraints, various adjuvants that are shown to enhance immune response to vaccines in adults are considered for early age vaccines. Although some of these adjuvants show promising results in animal experiments, mechanistic studies need to be conducted in detail since adult and neonatal in vivo environments may dictate different outcomes between the two age groups, especially because early-life adjuvant exposure may have long-lasting effects on immune system programming. Elucidation of age-specific immune responses to vaccines and adjuvants will help develop age-tailored strategies to develop safe and effective pediatric vaccines. Full article

(This article belongs to the Special Issue Innovations in Vaccines for Poorly Responding Populations)

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17 pages, 427 KB

Open AccessArticle

Development and Validation of an Extended Adult Vaccine Hesitancy Scale in Greek-Speaking Populations

by Andria Hadjikou, Irene Heraclidou and Alexandros Heraclides

Vaccines 2026, 14(7), 628; https://doi.org/10.3390/vaccines14070628 - 17 Jul 2026

Viewed by 204

Abstract

Background: Vaccine hesitancy (VH) is a complex global public health threat requiring validated tools for its assessment globally. This study aimed to evaluate an extended adult Vaccine Hesitancy Scale (aVHS) among Greek-speaking adults. Methods: This study evaluated a newly developed extended version of [...] Read more.

Background: Vaccine hesitancy (VH) is a complex global public health threat requiring validated tools for its assessment globally. This study aimed to evaluate an extended adult Vaccine Hesitancy Scale (aVHS) among Greek-speaking adults. Methods: This study evaluated a newly developed extended version of a widely used aVHS, incorporating five additional items on long-term safety, risk–benefit evaluation, vaccine-related harm, scientific credibility, and perceived alternatives, on a cross-sectional sample of 491 adults in Greece and Cyprus. Cross-cultural adaptation of the extended aVHS involved translation, back-translation, and pilot testing. Structural validity was assessed using parallel analysis, exploratory factor analysis (EFA), and reliability using Cronbach’s α and McDonald’s ω. Criterion validity was assessed against focus-group classification using ROC analysis in 68 participants. Results: A one-factor EFA solution appeared the most parsimonious, showing strong loadings for the original and extended aVHS (0.67–0.86 and 0.65–0.87), with similar explained variance (60.31% and 60.06%). The one-factor solution was confirmed by parallel analysis for both scales. Internal consistency was excellent, and slightly higher for the extended than the original aVHS (α = 0.95; ω = 0.95 vs. α = 0.92; ω = 0.93). The five newly added items performed strongly, with item–rest correlations of 0.69–0.85 and loadings of 0.72–0.87. Criterion validity was excellent, with a slightly higher AUC (0.991 vs. 0.981) and numerically higher classification performance for the extended than the original aVHS. Conclusions: The extended aVHS is a psychometrically coherent tool that improves the performance of the original scale among Greek-speaking individuals. This scale may enhance VH surveillance, aiding targeted vaccination communication strategies. Full article

(This article belongs to the Special Issue Vaccines and Vaccinations During and After the Pandemic Period)

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13 pages, 751 KB

Open AccessReview

Beyond PrEP: The Imperative for an HIV Vaccine to End the Epidemic in Africa

by Nicaise Ndembi, Morenike O. Folayan, Anthony Pilorget, Nyanda E. Ntinginya, Betty Mwesigwa, Trevor A. Crowell, Nyaradzo M. Mgodi and Jerome H. Kim

Vaccines 2026, 14(7), 627; https://doi.org/10.3390/vaccines14070627 - 17 Jul 2026

Viewed by 795

Abstract

The era of highly effective pre-exposure prophylaxis (PrEP) has transformed HIV prevention, yet global HIV incidence remains unacceptably high, particularly in sub-Saharan Africa. While antiretroviral-based prevention is critical, persistent structural barriers to access and adherence highlight the urgent need for a complementary preventive [...] Read more.

The era of highly effective pre-exposure prophylaxis (PrEP) has transformed HIV prevention, yet global HIV incidence remains unacceptably high, particularly in sub-Saharan Africa. While antiretroviral-based prevention is critical, persistent structural barriers to access and adherence highlight the urgent need for a complementary preventive HIV vaccine. In this narrative review and perspective, we argue that scientific progress toward an HIV vaccine must be matched by equally ambitious preparedness investments across three domains: manufacturing and supply chains, clinical trial and regulatory infrastructure, and delivery systems and community engagement. Drawing on lessons from the global rollout of PrEP, post-exposure prophylaxis (PEP), and the COVID-19 pandemic response, we outline a five-pillar strategic roadmap. This roadmap focuses on ensuring that a future HIV vaccine reaches the people who need it most from the moment of regulatory authorization, calling for co-investment in diverse platforms, binding advance market commitments, logistical simulation, and proactive planning for post-licensure effectiveness trials. Preparedness is not secondary to science; it is its essential partner. Full article

(This article belongs to the Special Issue The Need for an HIV Vaccine in the Era of Highly Effective PrEP)

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14 pages, 2528 KB

Open AccessArticle

Pilot-Scale Downstream Processing of Recombinant Influenza Virus Vectors Expressing Brucella spp. Antigens Using an Integrated Membrane-Chromatography Purification Platform

by Nurika Assanzhanova, Aigerim Sagymbayeva, Gaukhar Shynybekova, Kamshat Shorayeva, Sholpan Ryskeldinova, Aigerim Mailybayeva, Yeldos Myrzakhmetov, Ekaterina Yamanova, Rassul Sidikhov, Meiyrim Almezhanova, Samat Zhaksylyk, Zharkynai Absatova, Kuandyk Zhugunissov, Olga Chervyakova and Nurlan Akmyrzayev

Vaccines 2026, 14(7), 626; https://doi.org/10.3390/vaccines14070626 - 17 Jul 2026

Viewed by 679

Abstract

Background: Brucellosis remains a significant zoonotic infection affecting approximately 500,000 people worldwide annually, with no licensed human vaccine available. Recombinant influenza virus vectors expressing Brucella spp. antigens represent a promising vaccine platform. However, transitioning from laboratory constructs to clinical candidates requires validation [...] Read more.

Background: Brucellosis remains a significant zoonotic infection affecting approximately 500,000 people worldwide annually, with no licensed human vaccine available. Recombinant influenza virus vectors expressing Brucella spp. antigens represent a promising vaccine platform. However, transitioning from laboratory constructs to clinical candidates requires validation of scalable purification methods compliant with Good Manufacturing Practice (GMP) standards. This study aimed to develop and optimize a pilot-scale purification protocol for these vectors. Methods: Recombinant influenza A viruses (H5N1) expressing Brucella spp. antigens (Omp16, Omp19, L7/L12, Cu-Zn SOD) were propagated in MDCK cell culture. The optimized purification process included: (1) clarification; (2) ultrafiltration/diafiltration (100 kDa MWCO); (3) two-step chromatography (anion-exchange Q-Sepharose^® Fast Flow and multimodal Capto™ Core 700); and (4) sterile filtration. Process validation was performed across three independent pilot-scale batches (20 L each). Results: The purification process demonstrated high reproducibility for all constructs. Final preparations met established quality criteria: infectious titer ≥ 5.2 log₁₀ TCID₅₀/mL, hemagglutination activity 7.33 ± 0.58–8.33 ± 0.58 log₂, total protein content 157–305 μg/mL, residual host cell DNA < 10 ng/dose, and bacterial endotoxin levels ≤ 0.15 IU/mL. The overall recovery of infectious virus was 20–24%, an optimal value for multi-stage bioprocessing. Preservation of the target genetic insert was confirmed in all final preparations by PCR and sequencing. Conclusions: The developed integrated purification protocol yields vectors with high purification efficiency, preserving biological activity and meeting regulatory quality requirements for residual host cell DNA and endotoxins. The technological platform demonstrated versatility, robustness (inter-batch coefficient of variation for yield did not exceed 10–12%), and scalability, establishing a foundation for preclinical and clinical studies of candidate brucellosis vaccines. Full article

(This article belongs to the Special Issue Next-Generation Vaccines Based on Recombinant Proteins, Antibodies and Nucleic Acids)

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20 pages, 2576 KB

Open AccessArticle

Development of a New Feline Combination Vaccine Including a Novel RNA Particle Vaccine Against Feline Leukemia Virus

by Willem Huisman, Aart Mommen, Stephanie Basten, Kim Driessen, Peter Pepels, Qi Cao, Hans Holtslag, Melissa Ann Bourgeois and Jacqueline Pearce

Vaccines 2026, 14(7), 625; https://doi.org/10.3390/vaccines14070625 - 16 Jul 2026

Viewed by 598

Abstract

Background/Objectives: We describe the rationale, design and evaluation of a novel feline combination vaccine (Nobivac^® NXT HCPChFeLV) incorporating RNA particle technology against feline leukemia virus (FeLV) alongside live attenuated components for feline herpesvirus-1 (FHV), feline calicivirus (FCV), feline panleukopenia (FPL) and Chlamydia [...] Read more.

Background/Objectives: We describe the rationale, design and evaluation of a novel feline combination vaccine (Nobivac^® NXT HCPChFeLV) incorporating RNA particle technology against feline leukemia virus (FeLV) alongside live attenuated components for feline herpesvirus-1 (FHV), feline calicivirus (FCV), feline panleukopenia (FPL) and Chlamydia felis. Efficacy and safety outcomes from laboratory and field studies are presented. Methods: Nobivac NXT HCPChFeLV is a 0.5 mL, non-adjuvanted, lyophilized vaccine containing live attenuated FHV, FCV, FPL, and C. felis strains, and an alphavirus replicon-derived RNA particle expressing FeLV envelope glycoprotein (gp85). The primary vaccination schedule involved subcutaneous vaccination at 8–9 weeks of age with a booster 4 weeks later. Onset-of-immunity studies were performed 1 week post primary vaccination. Duration-of-immunity studies evaluated challenge both at 1 year and 3 years after primary vaccination with a booster at 1 year (FHV, FCV, FeLV); FPL duration was assessed at 3 years after primary vaccination; C. felis duration was assessed at 1 year. Clinical signs of disease, survival, leukopenia (FPL) and pathogen excretion were assessed. Safety was assessed in laboratory overdose/repeat-dose studies and in a field study comparing concurrent (non-mixed) use with rabies vaccination vs a positive control regimen. Results: Vaccination significantly reduced clinical disease following FHV, FCV and C. felis challenge and reduced FHV-associated mortality. Vaccinated cats were protected from FPL clinical disease, mortality, leukopenia, and FPL excretion. Persistent FeLV antigenemia was significantly prevented after primary vaccination and in 1-year-duration-of-immunity studies and was reduced 3 years after revaccination. The excretion of FHV, FCV and C. felis was significantly reduced in vaccinates vs controls. No serious adverse events were observed in laboratory studies; field vaccination was well tolerated with no injection-site reactions reported. Conclusions: Nobivac NXT HCPChFeLV provides robust, long-lasting protection against multiple feline pathogens, reduced pathogen shedding and demonstrated a favorable safety profile, supporting its use in feline preventive healthcare. Full article

(This article belongs to the Section Veterinary Vaccines)

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26 pages, 2894 KB

Open AccessReview

Maternal Immunization Against Respiratory Syncytial Virus: An Integrative Review of Efficacy, Safety, and Implementation

by Isadora Rodrigues Almeida, Marcela Fermoselle de Vita Silva, Taline de Brito Cavalcante, Giovanna Alves de Britto, Manuela Cândido Amaral dos Reis, Luis Fernando Lima Bueno, Luana dos Santos Ribeiro, Gustavo Yano Callado, Susana Cristina Aidé Viviani Fialho, Antonio Braga, Glória Calagna and Edward Araujo Júnior

Vaccines 2026, 14(7), 624; https://doi.org/10.3390/vaccines14070624 - 16 Jul 2026

Viewed by 446

Abstract

Respiratory syncytial virus (RSV) is a leading cause of severe lower respiratory tract infection in young infants and accounts for substantial morbidity, hospitalization, and mortality worldwide, with the highest burden concentrated in the first months of life, when immunological and anatomical immaturity favors [...] Read more.

Respiratory syncytial virus (RSV) is a leading cause of severe lower respiratory tract infection in young infants and accounts for substantial morbidity, hospitalization, and mortality worldwide, with the highest burden concentrated in the first months of life, when immunological and anatomical immaturity favors severe disease. Maternal vaccination has emerged as a strategy to bridge this window of vulnerability through the transplacental transfer of neutralizing antibodies. This integrative review synthesizes scientific articles published between 2022 and 2026, including systematic reviews, meta-analyses, narrative reviews, and position statements from national and international scientific societies, addressing the epidemiology, clinical manifestations, diagnosis, mechanism of action, efficacy, safety, and public health impact of maternal RSV immunization. The bivalent prefusion F protein vaccine (RSVpreF; Abrysvo^®), administered as a single intramuscular dose between 32 and 36 weeks of gestation, induces maternal IgG that is transferred to the fetus and confers passive protection during the first six months of life. In the phase 3 MATISSE trial, vaccination demonstrated 81.8% efficacy against severe RSV lower respiratory tract infection within 90 days of birth and 69.4% within 180 days, alongside reductions in hospitalization. The safety profile was favorable, with predominantly mild and transient adverse events; a numerical imbalance in preterm birth remains under surveillance and underlies the precautionary gestational window. Maternal vaccination and long-acting monoclonal antibodies (nirsevimab) are best regarded as complementary rather than competing strategies. Current evidence supports maternal immunization as one of the most effective measures to reduce the burden of RSV disease in early infancy. Full article

(This article belongs to the Special Issue Recent Progress of Vaccines for Respiratory Syncytial Virus (RSV))

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15 pages, 285 KB

Open AccessReview

Hepatitis B Vaccination in People Living with HIV: Bridging the Immunological Gap

by Christelle Radi, Jana Abu Faraj, Jad Idriss, Daniel J. Gromer, Diane Saint-Victor, Christiane S. Eberhardt, Nadine Rouphael and Suha Kalash

Vaccines 2026, 14(7), 623; https://doi.org/10.3390/vaccines14070623 - 16 Jul 2026

Viewed by 579

Abstract

Hepatitis B virus (HBV) infection remains a major driver of liver-related morbidity and mortality among people living with HIV (PLWH), yet vaccine-induced protection is frequently suboptimal. HIV-associated immune dysfunction, including CD4⁺ T-cell depletion, altered antigen presentation, impaired T follicular helper cell support, [...] Read more.

Hepatitis B virus (HBV) infection remains a major driver of liver-related morbidity and mortality among people living with HIV (PLWH), yet vaccine-induced protection is frequently suboptimal. HIV-associated immune dysfunction, including CD4⁺ T-cell depletion, altered antigen presentation, impaired T follicular helper cell support, and B-cell dysregulation, reduces seroprotection after standard recombinant HBV vaccines and may limit durability of antibody responses. Vaccine response is further influenced by HIV viral suppression, age, comorbidities, prior vaccine history, and baseline HBV serologic status, including isolated hepatitis B core antibody (anti-HBc) and occult HBV infection (OBI) considerations. Although antiretroviral therapy (ART) improves vaccine responsiveness, many PLWH fail to achieve protective hepatitis B surface antibody (anti-HBs) titers (≥10 mIU/mL) after conventional schedules, or experience antibody waning over time. Current guidelines recommend HBV vaccination for all susceptible PLWH with post-vaccination serologic testing and revaccination for nonresponders. Persistent implementation barriers, including incomplete series, vaccine hesitancy, stigma, and logistical constraints, continue to limit real-world impact. Emerging clinical trial data support CpG-adjuvanted HBV vaccines (HepB-CpG/Heplisav-B) and intensified dosing and schedules (double-dose or four-dose regimens) to improve seroprotection and generate higher peak anti-HBs titers, which may enhance durability. This review synthesizes guideline recommendations, immunologic mechanisms of hyporesponsiveness, predictors of vaccine response, and practical strategies to optimize HBV vaccination in PLWH. Full article

(This article belongs to the Special Issue Vaccines and Vaccination: HIV, Hepatitis Viruses, and HPV (2nd Edition))

33 pages, 4596 KB

Open AccessReview

From Vaccine Skepticism to Institutional Distrust: The Post-Pandemic Shift

by Francesco De Maria, Francesco Branda, Giancarlo Ceccarelli, Fabio Scarpa, Massimo Ciccozzi and Alessandro Russo

Vaccines 2026, 14(7), 622; https://doi.org/10.3390/vaccines14070622 - 16 Jul 2026

Viewed by 510

Abstract

Background: Vaccine hesitancy has traditionally been understood as a multifactorial phenomenon shaped by individual beliefs, risk perceptions, and access barriers. However, the COVID-19 pandemic has fundamentally transformed the relationship between citizens, science, and public institutions, raising the question of whether vaccine hesitancy [...] Read more.

Background: Vaccine hesitancy has traditionally been understood as a multifactorial phenomenon shaped by individual beliefs, risk perceptions, and access barriers. However, the COVID-19 pandemic has fundamentally transformed the relationship between citizens, science, and public institutions, raising the question of whether vaccine hesitancy has evolved into a broader form of institutional distrust. Objective: This narrative review synthesizes evidence on vaccine confidence, trust dynamics, misinformation, and post-pandemic attitudes to propose a new conceptual framework, i.e., institutional hesitancy, that reframes vaccine acceptance within the wider context of institutional credibility, transparency, and legitimacy. Methods: We conducted a narrative synthesis of peer-reviewed literature, surveillance reports, and cross-national surveys published between 2015 and 2026, focusing on trust in science, governments, public health agencies, healthcare systems, and regulatory authorities as determinants of vaccination behavior. Results: The evidence consistently demonstrates that institutional trust is among the strongest predictors of vaccine acceptance, often surpassing traditional demographic and knowledge-based variables. The pandemic exposed and amplified pre-existing fractures in the relationship between citizens and institutions, creating a legacy of institutional skepticism that extends beyond COVID-19 vaccines to routine immunization programs, seasonal vaccination campaigns, and future pandemic preparedness. Traditional information-based approaches, which assume that knowledge deficits drive hesitancy, have proven insufficient when trust is compromised. Instead, rebuilding vaccine confidence requires sustained investment in institutional transparency, community engagement, and accountable governance. Conclusions: The post-pandemic era calls for a fundamental reconceptualization of vaccine hesitancy. We propose the institutional hesitancy framework as a complementary lens that shifts the analytical focus from individual knowledge deficits to relational dynamics between citizens and institutions. Addressing this challenge requires moving beyond communication campaigns toward long-term strategies that restore institutional trust and strengthen the resilience of public health systems. Full article

(This article belongs to the Special Issue Vaccines and Vaccinations During and After the Pandemic Period)

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14 pages, 658 KB

Open AccessArticle

Human Papillomavirus Vaccine Intent and Associated Factors Among the Unvaccinated University Freshmen in the Largest University Town in China

by Hongcen Yao, Hongmei Lu, Qi Zhu, Jinhua Shen, Xiaoya Fu and Yihan Lu

Vaccines 2026, 14(7), 621; https://doi.org/10.3390/vaccines14070621 - 15 Jul 2026

Viewed by 293

Abstract

Background: Human papillomavirus (HPV) vaccine has been proven a safe, necessary, and effective measure against HPV infection. However, HPV vaccine uptake remains limited among university students in China. This study investigated HPV vaccine intent among university freshmen in the largest university town in [...] Read more.

Background: Human papillomavirus (HPV) vaccine has been proven a safe, necessary, and effective measure against HPV infection. However, HPV vaccine uptake remains limited among university students in China. This study investigated HPV vaccine intent among university freshmen in the largest university town in China. Methods: A cross-sectional online survey was conducted among unvaccinated female and male freshmen attending seven universities in Songjiang University Town, Shanghai, during 2024–2025. The questionnaire collected sociodemographic characteristics, HPV and HPV-vaccine-related knowledge, awareness, and vaccine intent. Factors associated with HPV vaccine intent were determined. Results: A total of 3397 valid questionnaires were collected, including female (60.02%) and male (39.98%) university freshmen. Overall, 76.12% were aware of HPV, 80.98% were aware of the HPV vaccine, and 84.31% expressed vaccine intent, with significantly higher rates among females than males (each p < 0.001). Socioeconomics, knowledge, awareness, sexual behavior, and HPV testing history were significantly associated with vaccine intent (each p < 0.05). The most common reason for no intent was perceived low risk of HPV-related diseases (40.53%). The most expected improvement measures were regulatory confirmation of vaccine safety and effectiveness (37.71%) and healthcare professionals’ recommendations (37.71%), with no gender difference (each p > 0.05). Notably, 4.00% refused HPV vaccination, regardless of improvement measures. Additionally, most respondents preferred financial supporting policies, regardless of gender or vaccine intent (each p > 0.05). Conclusions: University freshmen showed the disparity between high awareness/intent and low knowledge. Financial considerations may influence HPV vaccination decisions. Thus, improving knowledge, particularly among males, and providing financial support may enhance HPV vaccine intent. Full article

(This article belongs to the Section Human Papillomavirus Vaccines)

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21 pages, 1289 KB

Open AccessReview

Possible Mechanisms of mRNA-LNP Degradation: A Comprehensive Review

by MD Faizul Hussain Khan, Tahsina Islam, Abhishek Mishra and Amine A. Kamen

Vaccines 2026, 14(7), 620; https://doi.org/10.3390/vaccines14070620 - 15 Jul 2026

Viewed by 1270

Abstract

Messenger RNA-lipid nanoparticle (mRNA-LNP)-based drug products represent a promising platform for prophylactic and therapeutic applications. However, their limited stability poses significant challenges for storage and global distribution. The instability of mRNA-LNP products makes them dependent on ultra-cold chain systems. This instability is driven [...] Read more.

Messenger RNA-lipid nanoparticle (mRNA-LNP)-based drug products represent a promising platform for prophylactic and therapeutic applications. However, their limited stability poses significant challenges for storage and global distribution. The instability of mRNA-LNP products makes them dependent on ultra-cold chain systems. This instability is driven by various physicochemical factors, including temperature, pH, light exposure, oxidation, aggregation, shear stress, and humidity. These factors destabilize the physical and chemical integrity of both mRNA and lipid nanoparticle (LNP) components, leading to reduced vaccine potency and potentially increasing the risk of adverse safety outcomes. Understanding these factors and their mechanisms is crucial for retaining mRNA-LNP efficacy. This review discusses the key physicochemical instability factors and molecular degradation mechanisms responsible for the structural and functional deterioration of mRNA-LNP formulations. Further, we summarize the stabilization strategies and analytical methods used to detect and quantify the degradation of mRNA-LNP products. Addressing these challenges is critical for advancing next-generation nucleic acid-based drug products and LNP-based delivery systems. Full article

(This article belongs to the Special Issue Next-Generation Vaccine Platforms for Emerging Infections)

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34 pages, 864 KB

Open AccessPerspective

Generating Patient-Specific Anti-Tumor Responses with Non-Genetically Altered ‘Off-the-Shelf’ Allogeneic Cell Therapy: Leveraging Allo-Incompatibility for In Situ Vaccination

by Michael Har-Noy

Vaccines 2026, 14(7), 619; https://doi.org/10.3390/vaccines14070619 - 14 Jul 2026

Viewed by 380

Abstract

Background: Generating personalized anti-tumor immune responses remains a primary objective of precision oncology, yet conventional autologous platforms face critical biological and logistical constraints. While current research modifies allogeneic lines to evade host clearance, this perspective outlines a translational framework designed to leverage host-donor [...] Read more.

Background: Generating personalized anti-tumor immune responses remains a primary objective of precision oncology, yet conventional autologous platforms face critical biological and logistical constraints. While current research modifies allogeneic lines to evade host clearance, this perspective outlines a translational framework designed to leverage host-donor incompatibility as an active immunomodulatory asset to remodel the solid tumor microenvironment (TME). The framework proposes expanding a systemic pool of circulating, allo-specific host type 1 helper (Th1) memory cells via iterative intradermal injections of completely mismatched, activated donor Th1 cells, followed by a systemic intravenous rechallenge to provoke a controlled host-versus-graft (HvG) rejection response. Rapid intravascular clearance of donor cells is hypothesized to drive a transient, Type 1 cytokine wave that activates host effector populations via bystander pathways, promoting their extravasation into the tumor stroma to induce immunogenic cell death (ICD). This paradigm is contextualized by Phase 2B data in refractory microsatellite stable (MSS) metastatic colorectal cancer, where a dual-route allogeneic Th1 regimen demonstrated a median overall survival (OS) signal of 16.4 months despite an 89.5% conventional radiological progression rate. Ultimately, this framework provides a predictable, non-engineered conceptual mechanism to elicit a patient-specific adaptive immune response without ex vivo customization. Full article

(This article belongs to the Special Issue Cancer Vaccines and Immunotherapies)

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15 pages, 3003 KB

Open AccessArticle

Vaccination Coverage Among Preschool Children in Germany: Trends, Regional Disparities, and Determinants from School Enrolment Examinations in Two Metropolitan Regions

by Christopher Michael Dyer, Judith Welker, Kholoud Assaad, Nina Knab, Sanjida Rahman Mim, Maria Karathana, Anne Kühn, Sandra Kronmüller, Peter Tinnemann and Rebecca Zöllner

Vaccines 2026, 14(7), 618; https://doi.org/10.3390/vaccines14070618 - 14 Jul 2026

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Abstract

Background: Vaccinations are highly effective in preventing infectious diseases, which otherwise present a serious challenge to the health of individuals and public health. To identify potential gaps in vaccination coverage, we examined childhood vaccination levels in Frankfurt am Main (FFM) and the [...] Read more.

Background: Vaccinations are highly effective in preventing infectious diseases, which otherwise present a serious challenge to the health of individuals and public health. To identify potential gaps in vaccination coverage, we examined childhood vaccination levels in Frankfurt am Main (FFM) and the Rhein Neckar district (including Heidelberg city, RNHD) prior to, during and following the COVID-19 pandemic. Moreover, we explored various factors that appear to contribute to lower vaccination levels in specific communities in either or both locations. The results are intended to guide strategies for designing and improving vaccination services for specific groups in local health settings. Methods: A retrospective analysis was conducted to examine the vaccination rates of children in Frankfurt am Main and the Rhein Neckar district (including Heidelberg city) by using anonymized data from school entry examinations spanning the years 2017 to 2024. Data pre-processing, analysis, and visualization were performed using R (5.4.2). Frequencies and percentages were calculated for sociodemographic and vaccination rates (the completeness of the vaccination schedule recommended by STIKO for children). Multivariate logistic regression was performed to determine factors with a significant impact on vaccination uptake. Results: Multinomial logistic regression with ‘measles-only’ (Measles) as the reference category revealed distinct predictor patterns across vaccination levels. In both regions, children who completed preventive medical check-ups had higher odds of completing the schedule of vaccination plus at least one additional vaccine (ScheduledPlus) versus, measles-only vaccination. In RNHD, children from Eastern European language families and low- and medium-social-status backgrounds showed higher odds of completing the scheduled vaccinations without the recently introduced rotavirus vaccination (ScheduledNotRota), versus measles-only vaccination. In FFM, strong interaction effects were observed between medical examination completion and migration background, with children from non-German birthplaces showing dramatically reduced odds of complete vaccination when preventive care was incomplete. Discussion: The proportion of children with a complete vaccination status remained stable over the study period in both locations, with no evidence of post-pandemic decline. Nevertheless, this stability masks important heterogeneity in vaccine coverage patterns across sociodemographic groups. Systematic identification and modeling of interactions between nationality, parental employment, and healthcare utilization tell a compelling “double jeopardy” story that the effects of these risk factors are not additive but synergistic. Regular medical check-ups remain an important factor in ensuring high vaccination coverage among children until they start school and underscore the justification for such established preventive care programs. A nuanced understanding, however, is crucial for moving beyond simplistic, one-size-fits-all public health messaging. Full article

(This article belongs to the Section Vaccines and Public Health)

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Open AccessArticle

Association Between Varicella Vaccination Status and Self-Reported Contact History Among Confirmed Varicella Cases in Chaoyang District, Beijing, 2017–2025

by Yang Cao, Hao Wang, Ziwei Zhao, Zhen Li and Hai Fang

Vaccines 2026, 14(7), 617; https://doi.org/10.3390/vaccines14070617 - 14 Jul 2026

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Abstract

Objectives: To investigate associations between varicella vaccination and self-reported contact history with varicella or herpes zoster among clinically diagnosed varicella cases in Chaoyang District, Beijing, China. Methods: A retrospective observational study was conducted among 4441 clinically diagnosed varicella cases reported from 2017 to [...] Read more.

Objectives: To investigate associations between varicella vaccination and self-reported contact history with varicella or herpes zoster among clinically diagnosed varicella cases in Chaoyang District, Beijing, China. Methods: A retrospective observational study was conducted among 4441 clinically diagnosed varicella cases reported from 2017 to 2025. Multivariable logistic regression examined associations between vaccination status, number of doses, time since vaccination, and reported contact history with varicella and/or herpes zoster, adjusting for age, sex, and year of diagnosis. Results: Vaccinated cases had significantly higher odds of reporting contact with varicella or zoster compared with unvaccinated cases (OR = 1.34, 95% CI: 1.14–1.58). Both 1-dose and 2-dose recipients showed similar associations. A gradient of increasing odds was observed with longer time since vaccination, reaching OR = 3.17 (95% CI: 1.39–7.22) for 10 or more years since last dose. Associations were primarily driven by reported varicella contact rather than herpes zoster contact. Sensitivity analysis confirmed robustness of findings. Conclusions: Varicella vaccination was positively associated with reporting an identifiable exposure source. Vaccination status may influence completeness of exposure ascertainment in varicella surveillance and should be considered when interpreting contact tracing data. Full article

(This article belongs to the Section Epidemiology and Vaccination)

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Vaccines, Volume 14, Issue 7 (July 2026) – 95 articles

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