Inequality in Immunization 2025

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

Deadline for manuscript submissions: 15 September 2025 | Viewed by 2542

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Guest Editor
Department of Data and Analytics, World Health Organization, 20 Avenue Appia, 1211 Geneva, Switzerland
Interests: health inequality; monitoring; immunization
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Guest Editor
Department of Data and Analytics, World Health Organization, 20 Avenue Appia, 1211 Geneva, Switzerland
Interests: health systems; inequalities; social determinants of health
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Guest Editor
Department of Data and Analytics, World Health Organization, 20 Avenue Appia, 1211 Geneva, Switzerland
Interests: health inequalities; immunization; health policy
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Guest Editor
Immunization Analysis & Insights (IAI), World Health Organization, 20 Avenue Appia, 1211 Geneva, Switzerland
Interests: immunization; vaccine delivery
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GAVI, the Vaccine Alliance, Geneva, Switzerland
Interests: immunization; monitoring evaluation and learning
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Guest Editor
United Nations Children's Fund, New York, NY 10017, USA
Interests: immunization inequalities; urban immunization; primary health care strengthening

Special Issue Information

Dear Colleagues,

Significant progress has been made in improving access to immunization worldwide, particularly for children. However, the benefits of increased vaccine access are not evenly distributed within or across countries. Research and monitoring have identified persistent and emerging gaps in both childhood and adult immunization, influenced by factors such as socioeconomic status, place of residence, and gender. These have been examined in previous Special Issues of Vaccines in 2023 and 2024, which showcased advancements in our understanding of immunization inequalities and presented options for immunization delivery that offer promise in addressing disparities. Emerging challenges like vaccine refusal and hesitancy exacerbate vaccine inequalities during times of reform, stability, and crisis. In the latest Special Issue on Inequality in Immunization, the third in our series, we aim to expand the existing body of evidence. We welcome research and review articles that explore immunization inequalities and articles that effectively address these inequities in meaningful and lasting ways. Understanding and bridging gaps in immunization may serve as a catalyst for health systems’ reform and resilience on the path to achieving the Sustainable Development Goals and beyond.

Dr. Ahmad Reza Hosseinpoor
Dr. Devaki Nambiar
Dr. Nicole Bergen
Dr. M. Carolina Danovaro
Dr. Hope L. Johnson
Dr. Ibrahim Dadari
Guest Editors

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Keywords

  • health inequalities
  • immunization
  • vaccine inequality
  • events affecting vaccinology
  • monitoring

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Published Papers (3 papers)

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18 pages, 803 KiB  
Article
Decentralized Immunization Monitoring: Lessons Learnt from a Pilot Implementation in Kumbotso LGA, Kano State, Nigeria
by Adam Attahiru, Yahaya Mohammed, Fiyidi Mikailu, Hyelshilni Waziri, Ndadilnasiya Endie Waziri, Mustapha Tukur, Bashir Sunusi, Mohammed Nasir Mahmoud, Nancy Vollmer, William Vargas, Yusuf Yusufari, Gustavo Corrêa, Heidi W. Reynolds, Teemar Fisseha, Talatu Buba Bello, Moreen Kamateeka, Adefisoye Oluwaseun Adewole, Musa Bello, Imam Wada Bello, Sulaiman Etamesor, Joseph J. Valadez and Patrick Ngukuadd Show full author list remove Hide full author list
Vaccines 2025, 13(7), 664; https://doi.org/10.3390/vaccines13070664 - 20 Jun 2025
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Abstract
Background: Immunization coverage in Nigeria is low, with many children missing out on important lifesaving vaccines. To enable a better understanding of contextual factors towards increasing uptake, we piloted a Decentralized Immunization Monitoring (DIM) approach in the Kumbotso local government area (LGA) of [...] Read more.
Background: Immunization coverage in Nigeria is low, with many children missing out on important lifesaving vaccines. To enable a better understanding of contextual factors towards increasing uptake, we piloted a Decentralized Immunization Monitoring (DIM) approach in the Kumbotso local government area (LGA) of Kano state, Nigeria, to identify wards with low vaccination rates and understand why this is happening. The findings were used to improve routine immunization (RI) programs and reduce the number of unvaccinated children and children yet to receive their first dose of diphtheria–pertussis–tetanus (DPT) vaccine, referred to as Zero-Dose children (ZD). Methods: This study adopted a cross-sectional design approach using the Behavioural and Social Drivers of Vaccination (BeSD) framework and the Lot Quality Assurance Sampling (LQAS). The study population comprised caregivers of children aged 0–11 months and 12–23 months across the 11 wards in Kumbotso District, Kano State, Nigeria, using a segmentation sampling approach. The study covered 209 settlements selected using probability proportionate to size (PPS) sampling from the wards. Univariate and bivariate analyses were performed to show patterns and relations across variables. Results: Out of 418 caregivers surveyed, 98.1% were female. Delayed vaccination was experienced by 21.9% of children aged 4.5–11 months, while the prevalence of ZD was estimated at 26.8% amongst the older cohort (12–23 months). A total of 71.4% of the delayed group and 89.1% of the ZD group remained unvaccinated. Caregiver education, rural residence, and home births correlated with delayed/ZD status (p < 0.05). Logistic regression associated higher caregiver education with reduced delayed vaccination odds (OR:0.34, p < 0.001) and urban residence with lower ZD odds (OR:1.89, p = 0.036). The antigen coverages of BCG (81.5%), DPT3 (63.6%), and measles 1 (59.7%) all surpassed the national dropout thresholds. Kumbotso, Unguwar Rimi, and Kureken Sani wards were all identified as underperforming and therefore targeted for intervention. Negative vaccine perceptions (50% delayed, 53.6% ZD) and distrust in health workers (46.4% delayed, 48.2% ZD) were significant barriers, though the caregiver intent to vaccinate was protective (OR: 0.27, p < 0.001). The cost of accessing immunization services appeared to have a minor effect on coverage, as the majority of caregivers of delayed and ZD children reported spending less than 200 Naira (equivalent to USD 0.15) on transport. Conclusions: This pilot study highlighted the utility of LQAS and BeSD in identifying low-performing wards, barriers, and routine immunization gaps. Barriers included low caregiver education, rural residence, and negative vaccine perceptions/safety. Caregiver education and urban residence were protective factors against delayed and ZD vaccination, suggesting social and systemic barriers, particularly in rural and less educated populations. Antigen-specific coverage showed disparities, with dropouts for multi-dose vaccines exceeding the national thresholds of 10%. Targeted measures addressing education, trust, and systemic issues are needed. Findings emphasize decentralized monitoring, community engagement, and context-specific strategies to reduce ZD children and ensure equitable vaccination in Nigeria. Full article
(This article belongs to the Special Issue Inequality in Immunization 2025)
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14 pages, 605 KiB  
Article
Women’s Empowerment and Gender-Related Factors Associated with Maternal Tetanus Protection in 39 Low- and Middle-Income Countries
by Katherine Kirkby, Luisa Arroyave, Franciele Hellwig, M. Carolina Danovaro-Holliday, Nasir Yusuf, Shirin Heidari, Stephanie Shendale, Aluísio J. D. Barros and Ahmad Reza Hosseinpoor
Vaccines 2025, 13(6), 610; https://doi.org/10.3390/vaccines13060610 - 6 Jun 2025
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Abstract
Background: Tetanus is a vaccine-preventable disease, and therefore vaccination of women of reproductive age or during pregnancy is recommended alongside childhood tetanus vaccination. Gender-related factors related to social empowerment have been established as determinants of health service utilization; however, these social determinants have [...] Read more.
Background: Tetanus is a vaccine-preventable disease, and therefore vaccination of women of reproductive age or during pregnancy is recommended alongside childhood tetanus vaccination. Gender-related factors related to social empowerment have been established as determinants of health service utilization; however, these social determinants have not yet been explored directly with tetanus vaccination. In response, the aim of this study was to assess overall and country-specific gender-related barriers to maternal tetanus vaccine coverage. Methods: We used data from Demographic and Health Surveys (DHS) in 39 countries implemented between 2013 and 2022. Women’s empowerment was measured through three domains of the Survey-based Women’s emPowERment index (SWPER), as well as other gender-related variables. To assess the association between measures of women’s empowerment and gender-related factors and maternal tetanus immunization coverage, we used multilevel logistic models with pooled data from the 39 countries to analyze overall patterns, and we used multivariable logistic regression for each country-specific dataset to analyze country-level associations. Results: There were notable variations in the factors associated with tetanus vaccination across countries. Overall, we observed that higher levels of women’s empowerment, as measured through social independence and decision-making autonomy using the SWPER index, were associated with higher odds of maternal tetanus protection, with adjusted odds ratios of 1.23 (95%CI: 1.10–1.37) and 1.20 (95%CI: 1.02–1.40), respectively. However, women’s empowerment related to attitude to violence was not. Higher household wealth was also associated with higher odds of maternal tetanus protection overall. Conclusions: Women’s empowerment can improve the uptake of maternal tetanus vaccine. Addressing gender-related barriers may enhance vaccination coverage and contribute to the elimination of maternal and neonatal tetanus as a public health problem. However, these barriers vary from country to country, necessitating country-specific investigations to formulate tailored recommendations. Full article
(This article belongs to the Special Issue Inequality in Immunization 2025)
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16 pages, 2725 KiB  
Systematic Review
Effects of Pneumococcal Vaccination in Children Under Five Years of Age in the Democratic Republic of Congo: A Systematic Review
by Marcellin Mengouo Nimpa, Abel Ntambue, Christian Ngandu, M. Carolina Danovaro-Holliday, André Bita Fouda, Aimé Mwana-Wabene Cikomola, Jean-Crispin Mukendi, Dieudonné Mwamba, Adèle Daleke Lisi Aluma, Moise Désiré Yapi, Jean Baptiste Nikiema, Boureima Hama Sambo and Daniel Katuashi Ishoso
Vaccines 2025, 13(6), 603; https://doi.org/10.3390/vaccines13060603 - 31 May 2025
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Abstract
Background: In the Democratic Republic of Congo (DRC), the 13-valent pneumococcal conjugate vaccine (PCV13) was introduced in 2011 through a three-dose schedule, targeting infants as part of the Expanded Program on Immunization (EPI), to reduce pneumococcal-related morbidity and mortality. The aim of this [...] Read more.
Background: In the Democratic Republic of Congo (DRC), the 13-valent pneumococcal conjugate vaccine (PCV13) was introduced in 2011 through a three-dose schedule, targeting infants as part of the Expanded Program on Immunization (EPI), to reduce pneumococcal-related morbidity and mortality. The aim of this study was to determine the proportion of pneumonia and meningitis cases and deaths prevented in children under five following the introduction of this vaccine. Methods: This is a systematic review. We synthesized findings from studies carried out in the DRC between 2011 and 2023. We searched scientific articles, published and unpublished doctoral theses and conference proceedings. Only papers written in French or English and those reporting the results of original analytical studies were selected. We assessed the direct effect of PCV13 by calculating the proportion of infections avoided, using Odds Ratios or prevalence ratios related to infection or pneumococcal carriage. Results: Four studies were included in this review. Regarding pneumococcal carriage, when children received three PCV13 doses, the prevalence of carriage was reduced by 93.3% (95% CI: 86.3 to 96.6%), while a single dose did not significantly reduce the prevalence of carriage compared with children who had not received any dose. Concerning pneumonia prevention, three doses of PCV13 prevented 66.7% (95% CI: 37.2 to 82.2) of cases among vaccinated children. The proportion of meningitis attributable to S. pneumoniae prevented was 75.0% (95% CI: 6% to 93.3%) among children vaccinated with PCV13. S. pneumoniae serotypes 19F and 23F were the most frequent causes of invasive pneumonia in children. Serotypes 35B/35C, 15B/C, 10A and 11A/D were the most frequently identified causes of morbidity in Congolese children. In 2022, with PCV13 vaccination coverage at 79.0%, an estimated 113,359 cases of severe pneumonia and 17,255 pneumonia-related deaths were prevented in the DRC, with 3313 cases and 1544 deaths attributable to pneumococcal meningitis prevented. Conclusions: There is clear, but scattered, evidence of reduced colonization by S. pneumoniae and hospital admissions due to pneumococcal pneumonia and meningitis. The results also show that S. pneumoniae serotypes 35B/35C, 15B/C, 10A and 11A/D not included in PCV13 were the main cause of pneumococcal disease in unvaccinated or under-vaccinated children. These data support the need to continue improving vaccination coverage among children who are unvaccinated or incompletely vaccinated with PCV13 to reduce the burden of pneumococcal infections in the DRC. Full article
(This article belongs to the Special Issue Inequality in Immunization 2025)
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