Submit to Special Issue Submit Abstract to Special Issue Review for Vaccines Propose a Special Issue

Journal Menu

Journal Browser

► Journal Browser

Vaccines for the Vulnerable Population

Print Special Issue Flyer
Editor
Special Issue Information
Keywords
Benefits of Publishing in a Special Issue
Published Papers

A special issue of Vaccines (ISSN 2076-393X). This special issue belongs to the section "Vaccines and Public Health".

Deadline for manuscript submissions: 31 July 2026 | Viewed by 24150

Share This Special Issue

Editor

Dr. My Kieu Ha

E-Mail Website
Guest Editor

Vaccine and Infectious Disease Institute, University of Antwerp, 2000 Antwerpen, Belgium
Interests: infectious disease; epidemiology; rheumatology; T cell immunology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Vaccines save millions of lives each year. However, comparatively low vaccination rates among vulnerable populations, such as children, the elderly, socioeconomically disadvantaged individuals, etc., pose a significant burden on public health and the economy. Moreover, vaccine development and vaccination strategies often rely on data from healthy populations. Consequently, many vaccine recommendations for vulnerable groups are based on extrapolated data or post-licensure studies.

This Special Issue seeks to collect contemporary information on vaccination for vulnerable populations. We invite contributions from immunology and vaccinology experts to submit their original research, reviews, perspectives, and clinical trial reports. We are particularly interested in knowledge on the following themes:

1. The pathogen- or drug-induced mechanisms that may impact vaccine responsiveness;

2. Data on the immunogenicity and safety of standard and new vaccines;

3. Identifying biomarkers that could lead to more effective vaccination strategies.

Dr. My Kieu Ha
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 250 words) can be sent to the Editorial Office for assessment.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-anonymized peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Vaccines is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

vaccines
vulnerable populations
infectious diseases
immunization

Benefits of Publishing in a Special Issue

Ease of navigation: Grouping papers by topic helps scholars navigate broad scope journals more efficiently.
Greater discoverability: Special Issues support the reach and impact of scientific research. Articles in Special Issues are more discoverable and cited more frequently.
Expansion of research network: Special Issues facilitate connections among authors, fostering scientific collaborations.
External promotion: Articles in Special Issues are often promoted through the journal's social media, increasing their visibility.
Reprint: MDPI Books provides the opportunity to republish successful Special Issues in book format, both online and in print.

Further information on MDPI's Special Issue policies can be found here.

Published Papers (8 papers)

Download All Papers

Order results

Result details

Show export options Show export options

Select all

Export citation of selected articles as:

Research

Jump to: Review, Other

14 pages, 441 KB

Open AccessArticle

COVID-19 Vaccine Effectiveness in Individuals with Alcohol and Tobacco Use Disorders: A Propensity Score-Matched Study Using Nationwide Brazilian Data

by Fabrício Emanuel S. Oliveira, Daniella R. B. Martelli, Maria Christina L. Oliveira, Enrico A. Colosimo, Ana Cristina Simões e Silva, Ana Livia O. Andrade, Rafaela R. Herrerias, Lays R. C. Foligno, Isabella O. Barbosa, Hercílio Martelli-Junior and Eduardo A. Oliveira

Vaccines 2026, 14(5), 376; https://doi.org/10.3390/vaccines14050376 - 23 Apr 2026

Viewed by 599

Abstract

Background/Objectives: Individuals with alcohol use disorder (AUD) and tobacco use disorder (TUD) are at increased risk for severe COVID-19 outcomes. However, real-world evidence on vaccine effectiveness (VE) in these populations remains limited, particularly in low- and middle-income countries. This study aimed to evaluate the effectiveness of three or more COVID-19 vaccine doses against mortality in hospitalized patients with AUD and TUD in Brazil. Methods: This retrospective cohort study used data from the SIVEP Gripe database, a national surveillance system of hospitalized COVID-19 cases in Brazil. The study included adults aged ≥18 years with confirmed SARS-CoV 2 infection between February 2020 and June 2025. The intervention was defined as receipt of three or more vaccine doses (fully vaccinated) versus no doses (unvaccinated). Propensity score matching was performed separately for AUD and TUD cohorts. Vaccine effectiveness was estimated using McNemar’s test for paired samples, and the average treatment effect (ATE) and number needed to vaccinate (NNV) were calculated. Results: Among 2,184,723 hospitalized patients, 12,115 had AUD and 45,679 had TUD. After matching, VE against mortality was 42% (95% CI: 27.5–53.5) in the AUD group and 52.6% (95% CI: 46.5–58.1) in the TUD group, compared to 58.5% and 58.9% in their respective non-exposed counterparts. The ATE was consistent across groups (approximately −0.12), and the NNV to prevent one death was 8 (95% CI: 6–15 for AUD; 7–12 for TUD). Conclusions: Although VE was attenuated in individuals with AUD and TUD compared to the general population, the absolute benefit of vaccination remained substantial. Full article

(This article belongs to the Special Issue Vaccines for the Vulnerable Population)

► Show Figures

Figure 1

23 pages, 3243 KB

Open AccessArticle

Cost-Effectiveness of Infant Pneumococcal Conjugate Vaccination Strategies in Vietnam: A Stepwise Economic Evaluation

by Liping Huang, An Ta, Artem Antonov, Michael Groff and Phong Lan Nguyen

Vaccines 2026, 14(3), 220; https://doi.org/10.3390/vaccines14030220 - 27 Feb 2026

Viewed by 1357

Abstract

Background: Vietnam is one of few remaining countries without a pediatric pneumococcal National Immunization Program (NIP). However, four pneumococcal conjugate vaccines (PCVs) are available in Vietnam: 10-, 13-, 15-, and 20-valent PCVs (PCV10, PCV13, PCV15 and PCV20). Given the availability of multiple PCVs, selecting an optimal vaccination strategy is challenging. This paper aims to estimate the vaccination impact of these PCVs, with and without the implementation of a pediatric NIP, to inform decision-makers and healthcare providers. Methods: A Markov model was adapted to evaluate the impact of all vaccines administered under a 3 + 1 schedule (50% vaccine uptake with direct protection assumed only) and a hypothetical scenario including PCVs 2 + 1 in Vietnam’s pediatric NIP (90% uptake with both direct and indirect protection) from a payer’s perspective. For each scenario, we performed stepwise comparisons of each vaccine with the next higher-valent option: PCV13 versus PCV10, PCV15 versus PCV13, and PCV20 versus PCV15. Results: Under the 3 + 1 schedule, PCV13 and PCV20 were cost-effective versus PCV10 and PCV15, respectively. PCV15, however, was not cost-effective versus PCV13, though offering greater health benefit but at a higher total cost. Under the 2 + 1 schedule, PCV13 remained cost-effective over PCV10, while PCV15 was not cost-effective relative to PCV13. PCV20 was dominant over PCV15. Sensitivity analyses demonstrated results consistent with both reference cases. Conclusions: Vaccinating infants in Vietnam through the private market or an NIP with PCV13 or PCV20 was estimated to be more cost-effective or cost saving than strategies based on PCV10 or PCV15, respectively. These findings provide valuable evidence to inform policy decisions. Full article

(This article belongs to the Special Issue Vaccines for the Vulnerable Population)

► Show Figures

Figure 1

13 pages, 1030 KB

Open AccessArticle

Pneumococcal Vaccination Uptake Among People with HIV Following the Implementation of an On-Site Vaccination Service in an Italian Specialist Out-Patient Clinic

by Anna Lisa Ridolfo, Maria Vittoria Cossu, Letizia Oreni, Cristina Gervasoni, Giacomo Casalini, Debora Visigalli, Catia Rosanna Borriello, Andrea Giacomelli, Andrea Gori and Spinello Antinori

Vaccines 2026, 14(2), 176; https://doi.org/10.3390/vaccines14020176 - 13 Feb 2026

Cited by 1 | Viewed by 870

Abstract

Background: People with HIV (PWH) face elevated risk of pneumococcal disease despite optimal antiretroviral therapy. In Italy, pneumococcal vaccination coverage in adults remains suboptimal. For PWH, access barriers may be amplified because adult vaccinations are primarily delivered in primary care, whereas HIV care is mostly hospital-based. Methods: We conducted a retrospective, observational study at an HIV clinic in Milan, Italy, evaluating the impact of an on-site vaccination service implemented in January 2019. At baseline, 1854 PWH were in active follow-up; 135 (7.3%) had previously received pneumococcal vaccination. We assessed vaccination uptake (PCV13-PPSV23 sequential schedule or PCV20) among the remaining 1719 unvaccinated individuals through December 2023. A logistic regression analysis was used to identify factors associated with vaccine acceptance. Results: Over five years, 745/1719 individuals (43.3%) either initiated PCV13 + PPSV23 or received PCV20, representing a six-fold increase from baseline. Of 639 individuals receiving PCV13, 80.1% completed the sequence with PPSV23. Most vaccinations (80.8%) were administered on-site. In multivariable analysis, men who have sex with men showed higher uptake (aOR 1.56, 95% CI 1.25–1.95), while regular and irregular immigrants had significantly lower uptake (aOR 0.70 and 0.24, respectively) compared to Italian nationals. Conclusions: Integration of vaccination services into routine HIV care substantially improved pneumococcal vaccination uptake. However, with nearly half of eligible patients remaining unvaccinated, additional strategies are required to address vaccine hesitancy and inequities, particularly among immigrants, to achieve optimal pneumococcal coverage in PWH. Full article

(This article belongs to the Special Issue Vaccines for the Vulnerable Population)

► Show Figures

Figure 1

16 pages, 940 KB

Open AccessArticle

Acceptability, Usability, and Clinical Integration of a Clinic-Based Digital Game for HPV Education: Qualitative Perspectives from Adolescents, Parents, and Healthcare Providers

by Elizabeth Reifsnider, Satya Subedi, Nouran Ghonaim, Megan Whaley and Angela Chia-Chen Chen

Vaccines 2026, 14(2), 116; https://doi.org/10.3390/vaccines14020116 - 26 Jan 2026

Viewed by 879

Abstract

Background/Objectives: HPV vaccination is safe, effective, and recommended at ages 11–12, yet uptake remains suboptimal. Serious video games may offer an innovative strategy to deliver brief, engaging education during clinic visits. This qualitative paper, embedded within a mixed-methods study, examined adolescents’, parents’, and healthcare providers’ (HCPs’) perceptions of the acceptability, usability, and perceived clinical applicability of HPV Detective, a tablet-based digital game designed to provide HPV-related education to parent–child dyads during pediatric clinic wait times. Methods: Eight adolescent–parent dyads (N = 16) and three HCPs from university-affiliated pediatric clinics participated in 30–60-min semi-structured Zoom interviews. Interviews were audio-recorded, transcribed, and thematically analyzed by two coders, with discrepancies resolved by consensus and reviewed by a third researcher. Results: Participants identified five key dyadic themes and four HCP themes. Adolescents described the gameplay as intuitive and enjoyable, highlighting interactive challenges and realistic avatars. Parents valued the clarity of HPV information and noted that the game helped initiate health-related conversations. Both adolescents and parents suggested enhancements including voice narration and greater customization and agreed that the game was well suited for 10–15-min clinic wait times, with text messaging preferred for follow-up. HCPs emphasized challenges such as parental hesitancy and competing clinical demands and viewed the game as a feasible adjunct to support vaccine-related discussions. Conclusions: Findings suggest the acceptability, usability, and perceived clinical applicability of a brief, clinic-based digital game for HPV-related education and engagement among adolescents and their parents. Full article

(This article belongs to the Special Issue Vaccines for the Vulnerable Population)

► Show Figures

Figure 1

12 pages, 1030 KB

Open AccessArticle

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

Cited by 1 | Viewed by 3526

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 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. Full article

(This article belongs to the Special Issue Vaccines for the Vulnerable Population)

► Show Figures

Figure 1

Review

Jump to: Research, Other

19 pages, 681 KB

Open AccessReview

Oropouche Virus (OROV) Vaccine Development for Vulnerable Populations: Epidemiological Context, Challenges and Future Directions

by Wenrui Wu and Yiu-Wing Kam

Vaccines 2026, 14(3), 267; https://doi.org/10.3390/vaccines14030267 - 16 Mar 2026

Cited by 1 | Viewed by 1351

Abstract

Oropouche virus (OROV) is an emerging arthropod-borne virus in the Americas that has evolved from a pathogen historically restricted to forest environments into an increasingly important regional and international public health concern. Despite decades of documented circulation, the true burden of OROV infection remains substantially underestimated, largely because of frequent misdiagnosis and the high proportion of asymptomatic or subclinical infections. This review synthesizes current evidence on the historical emergence, epidemiology, transmission dynamics, and clinical features of OROV, with a particular focus on populations at increased risk due to biological susceptibility, environmental exposure, and limited access to healthcare. Drawing on seroepidemiological data, we demonstrate that OROV transmission is far more widespread than routine surveillance suggests and examine how factors such as age, pregnancy, immune status, underlying health conditions, occupational exposure, and healthcare accessibility interact to influence disease risk and detection. Although multiple vaccine platforms have shown promise in preclinical studies, progress toward clinical development remains constrained by limited immunological evidence, shortcomings of available animal models, diagnostic uncertainty, and structural barriers in endemic regions. We propose that future OROV vaccine development prioritize population-specific needs rather than focusing solely on technological platforms, and that effective prevention will require integrating vaccination with strengthened surveillance, improved diagnostics, and equitable delivery systems. Full article

(This article belongs to the Special Issue Vaccines for the Vulnerable Population)

► Show Figures

Figure 1

19 pages, 689 KB

Open AccessEditor’s ChoiceReview

Maternal Immunization: Current Evidence, Progress, and Challenges

by Veronica Santilli, Mayla Sgrulletti, Giorgio Costagliola, Alessandra Beni, Maria Felicia Mastrototaro, Davide Montin, Caterina Rizzo, Baldassarre Martire, Michele Miraglia del Giudice and Viviana Moschese

Vaccines 2025, 13(5), 450; https://doi.org/10.3390/vaccines13050450 - 24 Apr 2025

Cited by 12 | Viewed by 11088

Abstract

Maternal immunization is a key strategy for protecting pregnant individuals and newborns from infectious diseases. This review examines the mechanisms and benefits of maternal immunization, with a focus on transplacental IgG transfer and immune system interactions. We provide an overview of current recommendations and the safety and efficacy profiles of maternal vaccines, including influenza, tetanus–diphtheria–acellular pertussis (Tdap), respiratory syncytial virus (RSV), COVID-19, and hepatitis B. Additionally, we analyze the barriers to maternal immunization, such as misinformation, vaccine hesitancy, and disparities in healthcare access, while exploring potential strategies to overcome these challenges through targeted educational initiatives, improved provider communication, and policy-driven interventions aimed at increasing vaccine confidence and accessibility. Finally, this review highlights recent innovations and future directions in maternal immunization, including emerging vaccines for Group B Streptococcus and cytomegalovirus. Expanding immunization programs and advancing research on maternal–fetal immunity are essential to optimizing vaccination strategies, improving public health outcomes, and reducing the global burden of infectious diseases. Full article

(This article belongs to the Special Issue Vaccines for the Vulnerable Population)

► Show Figures

Figure 1

Other

Jump to: Research, Review

12 pages, 243 KB

Open AccessOpinion

Vaccinations for Elite Athletes

by Olli Ruuskanen, Maarit Valtonen, Olli J. Heinonen, Matti Waris and Jussi Mertsola

Vaccines 2025, 13(9), 931; https://doi.org/10.3390/vaccines13090931 - 31 Aug 2025

Cited by 1 | Viewed by 3031

Abstract

Elite athletes are at an increased risk of infections due to behavioral and social factors and frequent travel. Furthermore, heavy physical exercise may induce immunosuppression. Most infections in athletes are acute respiratory illnesses (ARIs) with various viral etiologies. Although athletes, as young, healthy adults, are not at risk for severe infections, a prolonged ARI may ruin a training season or a significant competition or may spread within a sports team. Many common infections are vaccine-preventable. This Opinion advocates for more active vaccination among athletes, although some of the vaccines are not officially recommended for young adults. New respiratory syncytial virus (RSV) protein vaccines are effective and well-tolerated. Yearly influenza and COVID-19 vaccinations are strongly recommended. Conjugated polyvalent pneumococcal vaccines are recommended because they may also induce protection against respiratory viral infections. Pertussis and measles outbreaks are occurring globally. The history of measles vaccination should be reviewed, and consideration should be given to a pertussis booster vaccination (Tdap). A recombinant vaccine can effectively prevent herpes zoster. The vaccination of elite athletes is a cost-effective and powerful tool, but it is currently underused. The sports medicine community can address vaccine hesitancy among athletes by listening to their concerns and giving accurate information. Full article

(This article belongs to the Special Issue Vaccines for the Vulnerable Population)

Show export options Show export options

Select all

Export citation of selected articles as:

Displaying articles 1-8

Journal Menu

Journal Browser

Vaccines for the Vulnerable Population

Share This Special Issue

Editor

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (8 papers)

Research

Review

Other

Further Information

Guidelines

MDPI Initiatives

Follow MDPI