Strengthening global vaccine access for adolescents and adults

Maintaining Immunizations for Vaccine-Preventable Diseases in a Changing World

Immunization has saved an estimated 154 million lives over the past 50 years since the launch of the Essential (formerly Expanded) Program on Immunization in 1974, representing 6 lives saved every minute, every year, for 50 years. But achieving and maintaining high immunization coverage have required sustained political and public commitment, financial resources, strong partnerships, research and innovation, and communication and advocacy. New and evolving challenges to maintaining high immunization coverage have emerged alongside long-standing stubborn obstacles. We review some of these key challenges to immunization in this dynamic, changing world and summarize some promising solutions. Success in some regions of the world in eliminating polio, measles, and rubella, and reducing morbidity and mortality from other vaccine-preventable diseases, should provide hope that progress can be made in achieving and maintaining high immunization coverage. We cannot afford to do otherwise.

Factors Associated with Vaccination Adequacy in People Living with HIV: A Cross-Sectional Study

People living with HIV (PLHIV) are at greater risk of illness and death from vaccine-preventable diseases. This study aimed to identify the predictors associated with the recommended vaccination schedule for this group. This was a single-center cross-sectional study conducted in a large Brazilian municipality, evaluating the vaccination statuses of 645 PLHIV for nine immunizers. The primary outcome was the adequacy of the vaccination schedule. The vaccination status was assessed for the diphtheria/tetanus, hepatitis B, hepatitis A, measles/mumps/rubella, yellow fever, 13- and 23-valent pneumococcal, meningococcal C, and HPV vaccines. Those who had received all of the recommended vaccinations in accordance with the schedule established by the government at the time of the assessment, without any delays, were classified as having received an "adequate schedule". The independent variables included sociodemographic, clinical-epidemiological, and social vulnerability factors, analyzed by multiple logistic regression with adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs). Only 47 individuals (7.3%) had an adequate vaccination schedule for all vaccines. The vaccines with the highest adequacy rate were diphtheria and tetanus (533; 82.6%), and the one with the lowest rate was measles/mumps/rubella (MMR) (243; 37.7%). The main predictors of a complete vaccination schedule were the age group, place of clinical follow-up, and where they received their last doses of vaccines. Educational interventions for PLHIV and health professionals are needed to improve the vaccination coverage in this group.

Health Promotion and Chronic Disease Prevention at the Workplace

The concept of workplace safety and health has focused largely on preventing accidents and on minimizing hazardous exposures. However, because workers spend a substantial part of their waking hours at the workplace, the potential to influence the health of a large proportion of the world's population through the workplace is enormous. The opportunities to carry out health promotion and chronic disease prevention activities at the workplace are countless, including (a) health screening; (b) tobacco cessation activities; (c) the promotion of healthy food choices and weight loss; (d) active breaks with physical exercise in terms of microexercise, enhancement of infrastructure to stimulate physical activity, and organization of work tasks to facilitate incidental physical activity; and (e) routine vaccinations. This review discusses the key factors necessary to implement health promotion and chronic disease prevention programs at the workplace (SWOLE model) and discusses the different foci and possibilities with respect to the differing nature of work for the blue- versus white-collar workforce.

Global burden of vaccine-associated multiple sclerosis, 1967-2022: A comprehensive analysis of the international pharmacovigilance database

Vaccine-associated multiple sclerosis (MS) is rare, with insufficient evidence from case reports. Given the scarcity of large-scale data investigating the association between vaccine administration and adverse events, we investigated the global burden of vaccine-associated MS and potential related vaccines from 1967 to 2022. Reports on vaccine-associated MS between 1967 and 2022 were obtained from the World Health Organization International Pharmacovigilance Database (total number of reports = 120 715 116). We evaluated global reports, reporting odds ratio (ROR), and information components (IC) to investigate associations between 19 vaccines and vaccine-associated MS across 156 countries and territories. We identified 8288 reports of vaccine-associated MS among 132 980 cases of all-cause MS. The cumulative number of reports on vaccine-associated MS gradually increased over time, with a substantial increase after 2020, owing to COVID-19 mRNA vaccine-associated MS. Vaccine-associated MS develops more frequently in males and adolescents. Nine vaccines were significantly associated with higher MS reporting, and the highest disproportional associations were observed for hepatitis B vaccines (ROR 19.82; IC025 4.18), followed by encephalitis (ROR 7.42; IC025 2.59), hepatitis A (ROR 4.46; IC025 1.95), and papillomavirus vaccines (ROR 4.45; IC025 2.01). Additionally, MS showed a significantly disproportionate signal for COVID-19 mRNA vaccines (ROR 1.55; IC025 0.52). Fatal clinical outcomes were reported in only 0.3% (21/8288) of all cases of vaccine-associated MS. Although various vaccines are potentially associated with increased risk of MS, we should be cautious about the increased risk of MS following vaccination, particularly hepatitis B and COVID-19 mRNA vaccines, and should consider the risk factors associated with vaccine-associated MS.

Global burden of vaccine-associated anaphylaxis and their related vaccines, 1967-2023: A comprehensive analysis of the international pharmacovigilance database

BACKGROUND

Vaccine-associated anaphylaxis is a rare but life-threatening reaction that occurs within minutes to hours of exposure to allergens. As studies utilizing large-scale data to investigate this topic are limited, further research is needed to assess its burden, long-term trends, and associated risk factors so as to gain a comprehensive understanding of vaccine-associated anaphylaxis globally. Therefore, this study aimed to investigate the global burden of vaccine-associated anaphylaxis and related vaccines.

METHOD

This study utilized the World Health Organization International Pharmacovigilance Database, in which reports of vaccine-associated anaphylaxis between 1967 and 2023 were obtained (total reports = 131,255,418). We estimated the global reporting counts, reported odds ratio (ROR), and information component (IC) to identify the relationship between 19 vaccines and associated anaphylaxis in 156 countries and territories.

RESULTS

We identified 31,676 reports of vaccine-associated anaphylaxis among 363,290 reports of all-cause anaphylaxis. The cumulative number of reports on vaccine-associated anaphylaxis has gradually increased over time, with a dramatic increase after 2020, owing to reports of COVID-19 mRNA vaccine-associated anaphylaxis. The typhoid vaccines were associated with the most anaphylactic reports (ROR: 4.35; IC0.25 : 1.86), followed by encephalitis (3.27; 1.45), hepatitis B (2.69; 1.30), cholera (2.65; 0.54), hepatitis A (2.44; 1.12), influenza (2.36; 1.16), inactivated whole-virus COVID-19 (2.21; 1.02), and COVID-19 mRNA vaccines (1.89; 0.79). In terms of age- and sex-specific risks, vaccine-associated anaphylaxis reports develop more frequently in females and at young ages. The Ad5-vectored COVID-19 vaccine anaphylaxis reports were associated with the highest fatality rate (15.0%).

CONCLUSIONS

Although multiple vaccines are associated with various spectra and risks of anaphylaxis, clinicians should recognize the possibility of anaphylaxis occurring with all vaccines, particularly the COVID-19 mRNA and inactivated whole-virus COVID-19 vaccines, and consider the risk factors associated with vaccine anaphylaxis reports. Further studies are warranted to identify better ways of preventing vaccine-associated anaphylaxis.

Lessons from a decade of adult vaccine rollout in low- and middle-income countries: a scoping review

INTRODUCTION

The historical focus of vaccines on child health coupled with the advent of novel vaccines targeting adult populations necessitates exploring strategies for adult vaccine implementation.

AREAS COVERED

This scoping review extracts insights from the past decade's experiences introducing adult vaccines in low- and middle-income countries. Among 25 papers reviewed, 19 focused on oral cholera vaccine, 2 on Meningococcal A vaccines, 2 on tetanus toxoid vaccine, 1 on typhoid vaccine, and 1 on Ebola vaccine. Aligned with WHO's Global Framework for New TB Vaccines for Adults and Adolescents, our findings center on vaccine availability, accessibility, and acceptance.

EXPERT OPINION

Availability findings underscore the importance of understanding disease burden for prioritization, multi-sectoral collaboration during planning, and strategic resource allocation and coordination. Accessibility results highlight the benefits of leveraging existing health infrastructure and adequately training healthcare workers, and contextually tailoring vaccine delivery approaches to reach challenging sub-groups like working male adults. Central to fostering acceptance, resonant sensitization, and communication campaigns engaging the communities and utilizing trusted local leaders countered rumors and increased awareness and uptake. As we approach the introduction of a new adult TB vaccine, insights from this review equips decision-makers with key evidence-based recommendations to support successful and equitable vaccinations targeting adults.

Voluntary Medical Male Circumcision to Reduce HIV Acquisition and Transmission

PURPOSE OF REVIEW

This commentary introduces the special Global Health Section on the state of voluntary medical male circumcision (VMMC) programs and current knowledge as to role of VMMC prevention of HIV infection acquisition in men and, indirectly, women.

RECENT FINDINGS

Since the first clinical trial of VMMC in Africa was published in 2005, implementation of programs has depended on illuminating best practices and key obstacles in the effort to expand VMMC in areas of high HIV prevalence to reduce HIV acquisition among men, with consequent benefits that uninfected men will not infect others. Global efforts are focused on sub-Saharan Africa, given the favorable expected impact of VMMC deployment where HIV incidence is high and circumcision rates are low. With estimated field effectiveness estimated to exceed 60%, reduced HIV risk for circumcised men in sub-Saharan Africa based on a once-only minor surgical intervention provides extraordinary preventive benefits. Where high VMMC rates have been achieved, declining HIV incidence rates may be partially or substantially attributed to VMMC, but this remains to be investigated. Articles in this special section address achievements, obstacles and risks, and plans for future progress in partnership with affected communities.

Understanding Primary Care Physician Vaccination Behaviour: A Systematic Review

BACKGROUND

Vaccine hesitancy decreases adult vaccination coverage and has been recognized by WHO as a major health threat. Primary care physicians (PCP) play a key role in vaccination by giving vaccine counselling to their patients. The aim of this systematic review is to identify the knowledge, beliefs, attitudes and barriers (KBAB) associated with own vaccination and patient recommendation in primary care physicians.

METHODS

MEDLINE/PubMed, EMBASE and Cochrane Library databases were used to search and identify relevant studies based on their title and abstract. In the next step, the full text of each previously selected article was read for eligibility. Articles were selected by two independent reviewers and data extraction was performed using tables. The following information was extracted: methodological characteristics, demographic factors, professional characteristics, and intrinsic or extrinsic factors influencing vaccination or recommendation.

RESULTS

Our search yielded 41 eligible papers, data-sources, previous practices, belief in the effectiveness or safety of the vaccine, perceived risk, and trust in health authorities were all shown to be related to own vaccination and patient recommendation.

CONCLUSION

Internet is the main source of information for PCP related to vaccine hesitancy. It is therefore essential to increase the presence and access to pro-vaccination content in this area. In addition, involving PCP in the establishment of vaccination recommendations could improve their credibility in the institutions. On the other hand, training in communication skills and establishing reminder systems could reflect higher vaccination coverage among their patients.

Persistence and risk factors of high-risk human papillomavirus infection among HIV positive and HIV negative tanzanian women: a cohort study

BACKGROUND

High-risk (HR) human papillomavirus (HPV) persistence is the most important risk factor for cervical cancer. We have assessed the type-specific HR HPV persistence among HIV positive and HIV negative Tanzanian women and factors associated with HR HPV persistence.

METHODS

In a cohort study including 4080 Tanzanian women, 3074 attended follow-up examination (up to 32 months after enrollment). Cervical samples were obtained for liquid-based cytology and HPV DNA testing using Hybrid Capture 2 and Inno-Lipa Extra II. Information on lifestyle factors was collected through a personal interview. The probability of HR HPV persistence at a given time point since enrollment was estimated non-parametrically using the EMICM algorithm.

RESULTS

Among the 462 women HR HPV positive at enrollment, 158 had at least one identical type detected at follow-up. The probability of persistence at 18 months after enrollment was 34.2 (95% CI 29.0-39.4). Stratifying by HIV status, the persistence probability was 42.9% (95% CI 33.5-51.9) among HIV positive, and 28.0% (95% CI 22.1-34.2) among HIV negative. Overall, HR HPV persistence was most common for HPV58, 35, 16, 31, and 52. Among HIV positive women it was HPV45, and HPV16, followed by HPV58 and HPV18, and among HIV negative women it was HPV31, HPV33 and HPV58. Risk factors associated with persistence of HR HPV were older age, longer interval between enrollment and follow-up, binge drinking, and HIV status.

CONCLUSIONS

HR HPV persistence was common in Tanzania, and most common among HIV positive women. Overall, persistence was most frequent for HPV 58, 35, 16, 31 and 52. The nonavalent HPV vaccine should be considered.

Influence of schistosomiasis on host vaccine responses

Schistosomiasis is a debilitating helminthiasis which commonly establishes as a chronic infection in people from endemic areas. As a potent modulator of the host immune response, the Schistosoma parasite and its associated products can directly interfere with its host's ability to mount adequate immune responses to unrelated antigens. As a result, increased attention is gathering on studies assessing the influence of helminths, particularly the causal agent of schistosomiasis, on host responsiveness to vaccines. However, to date, no consensus has been drawn regarding the influence of schistosomiasis on host vaccine responses. Here, we review available evidence on the influence of transgenerational and direct Schistosoma parasite exposure on host immune responses to unrelated vaccines. In addition, we evaluate the potential of praziquantel (PZQ) treatment in restoring schistosomiasis-impacted vaccine responses.

Vaccination coverage and adherence to a dengue vaccination program in the state of Paraná, Brazil

The success of vaccination programs depends on the level of acceptance of the vaccine to achieve high vaccine coverage rates (VCR). Vaccine hesitancy is a challenge, especially concerning new vaccines. Dengue vaccine, Dengvaxia®, was licensed in Brazil in 2015 and implemented, in a pioneering publicly-funded initiative in the state of Paraná, between 2016 and 2018. The vaccination program took place in five phases in the 30 municipalities most affected by dengue in the state, targeting individuals from nine to 44 years-old in two cities and from 15 to 27 years-old in the other 28 municipalities, totaling a target population of 500,000 individuals. A cross-sectional descriptive study was carried out to assess VCR and adherence to the dengue vaccine in this program. VCR, dropout ratio (DR), and compliance with the vaccination schedule (CVS) were analyzed by sex, age group, and municipality size. A total of 302,603 individuals (60.5%) received ≥ 1 dose, 44.2% received ≥ 2 doses, and 28.6% 3 doses. The DR was 52.8%. Among individuals who started vaccination, 40.6% achieved CVS. The highest VCR, highest CVS, and lowest DR occurred in the age group from 9 to 14 years old and from 28 to 44 years old and in smaller municipalities. A greater proportion of men started vaccination (male 64.0%; female 57.1%) however, the DR was higher in men (male 55.4%; female 49.9%), and a higher percentage of women completed the vaccination schedule according to the recommendations (CVS male 37.8%; female 43.6%). Differences were noted in the CVS according to the initial phase of the program (first phase 50.8%; second phase 18.8%). The heterogeneity in vaccine uptake and compliance according to sex, age, and municipality size suggests the need for differentiated strategies to address challenges with new and multiple-dose vaccines.

Health systems constraints and facilitators of human papillomavirus immunization programmes in sub-Saharan Africa: a systematic review

Given the vast investments made in national immunization programmes (NIPs) and the significance of NIPs to public health, it is important to understand what influences the optimal performance of NIPs. It has been established that well-performing NIPs require enabling health systems. However, systematic evidence on how the performance of health systems impacts on NIPs is lacking, especially from sub-Saharan Africa. We conducted a qualitative systematic review to synthesize the available evidence on health systems constraints and facilitators of NIPs in sub-Saharan Africa, using human papillomavirus immunization programmes as a proxy. Fifty-four articles published between 2008 and 2018 were found to be eligible. Data extraction was guided by an analytical model on the interface between NIPs and health systems. A cross-cutting thematic analysis of the extracted data was performed. This systematic review provides evidence necessary for informing ongoing health systems strengthening initiatives in sub-Saharan Africa. There is evidence to suggest that NIPs in sub-Saharan Africa have surmounted significant health systems constraints and have achieved notable public health success. This success can be attributed to strong political endorsement for vaccines, clear governance structures and effective collaboration with global partners. Despite this, significant health systems constraints persist in service delivery, vaccine communication, community engagement, the capacity of the health workforce and sustainable financing. These constraints could derail further progress if not addressed through health systems strengthening efforts. There is a need to expand the research agenda to include the comprehensive evaluation of health systems constraints and facilitators of NIPs within sub-Saharan Africa.

The impact of frost-damage on the quality and quantity of the secreted antigen-specific IgG repertoire

Freezing of alum-based vaccines drastically alters their colloidal composition and leads to irreversible cluster formation. The loss of stability is well described, but the impact of frost damage on the functionality of the induced and secreted antibody repertoire has not been studied in detail. We therefore applied our single-cell measurement platform to extract the frequencies of Immunoglobulin G-secreting cells in combination with individual secretion rates and affinities. We showed that, frost-damaged or not, the tested vaccine was able to generate similar frequencies of total and antigen-affine IgG-secreting cells. Additionally, the frost-damaged vaccine stimulated a similar T-cell cytokine secretion pattern when compared to the regularly stored vaccine. However, frost-damaged vaccines induced no efficient affinity maturation and a complete collapse of the affinity distribution was observed. This study unveiled the impact of frost-damage to alum-based vaccines on the induced secreted antibody repertoire, and illustrated the power of functional single-antibody analysis.

Quantitative modeling of the effect of antigen dosage on B-cell affinity distributions in maturating germinal centers

Affinity maturation is a complex dynamical process allowing the immune system to generate antibodies capable of recognizing antigens. We introduce a model for the evolution of the distribution of affinities across the antibody population in germinal centers. The model is amenable to detailed mathematical analysis and gives insight on the mechanisms through which antigen availability controls the rate of maturation and the expansion of the antibody population. It is also capable, upon maximum-likelihood inference of the parameters, to reproduce accurately the distributions of affinities of IgG-secreting cells we measure in mice immunized against Tetanus Toxoid under largely varying conditions (antigen dosage, delay between injections). Both model and experiments show that the average population affinity depends non-monotonically on the antigen dosage. We show that combining quantitative modeling and statistical inference is a concrete way to investigate biological processes underlying affinity maturation (such as selection permissiveness), hardly accessible through measurements.

Health Care Professionals' Perspectives on Life-Course Immunization: A Qualitative Survey from a European Conference

Today, fewer children die each year from vaccine-preventable diseases than older adults. Health systems need new immunization strategies to tackle the burden of vaccine-preventable disease in an aging society. A life-course immunization (LCI) approach-which entails vaccination throughout an individual's lifespan-enables adults to age with reduced risk to disease, thereby enabling healthy, active and productive aging. We conducted an audience response system (ARS)-based survey to investigate HCP perspectives on LCI in an opportunistic sample of 222 health care professionals (HCPs) from around the world who attended a European infectious diseases conference. Survey results show that LCI is a priority for HCPs (77.4%-88.6%), with most of them stating the need to frame it as a part of a healthy lifestyle (91.0%-100.0%). Insufficient LCI recommendations by vaccine providers (12.9%-33.3%) and governments (15.2%-41.9%) and insufficient targeted budget allocation (6.1%-21.7%) were indicated as the main barriers to implement LCI, ahead of vaccine hesitancy (9.7%-15.2%). HCPs were willing to make LCI a gateway to healthy aging but need support to work together with other stakeholders involved in the vaccination journey. This could be a step towards equitable health care for all of society.

Injectable Hydrogels Coencapsulating Granulocyte-Macrophage Colony-Stimulating Factor and Ovalbumin Nanoparticles to Enhance Antigen Uptake Efficiency

The combination of an antigen and adjuvant has synergistic effects on an immune response. Coadministration of an antigen and a granulocyte-macrophage colony-stimulating factor (GM-CSF) hydrogel delivery system will afford a novel strategy for enhancement of an immune response because of the dual role of the hydrogel as a vaccine carrier with a sustained release and a platform for recruiting dendritic cells (DCs). Herein, an injectable poly(caprolactone)-poly(ethylene glycol)-poly(caprolactone) thermosensitive hydrogel coencapsulating GM-CSF and ovalbumin nanoparticles was developed to enhance antigen uptake efficiency. The GM-CSF released from the hydrogel ensured accumulation of DCs; this effect improved the antigen uptake efficiency with the targeted delivery to antigen-presenting cells. Furthermore, the dual delivery system induced a stronger immune effect, including higher CD8⁺ T proportion, interferon γ secretion, and a greater cytotoxic T lymphocyte response, which may benefit from the recruitment of DCs, increasing antigen residence time, and the controllable antigen release owing to the combined effect of the hydrogel and nanoparticles. Meanwhile, the real-time antigen delivery process in vivo was revealed by a noninvasive fluorescence imaging method. All of the results indicated that the visible dual delivery system may have a greater potential for the efficient and trackable vaccine delivery.