Immunization: vital progress, unfinished agenda

Vaccination decision-making among mothers of children 0-12 months old in Nigeria: A qualitative study

The contribution of vaccination to global health, especially in low-middle-income countries is one of the achievements in global governance of modern medicine, averting 2-3 million child deaths annually. However, in Nigeria, vaccine-preventable-diseases still account for one-in-eight child deaths before their fifth-year birthday. Nigeria is one of the ten countries where 4.3 million children under five are without complete immunization. Therefore, the goal of this contribution is to shed light on the reasons to set a foundation for future interventions. To conduct focus groups, a simplified quota sampling approach was used to select mothers of children 0-12 months old in four geographical clusters of Nigeria. An interview guide developed from the 5C psychological antecedence model was used (assessing confidence, complacency, calculation, constraints, collective responsibility); two concepts were added that had proved meaningful in previous work (religion and masculinity). The data were analyzed using a meta-aggregation approach. The sample was relatively positive toward vaccination. Still, mothers reported low trust in vaccine safety and the healthcare system (confidence). Yet, they had great interest in seeking additional information (calculation), difficulties in prioritizing vaccination over other equally competing priorities (constraints) and were aware that vaccination translates into overall community wellbeing (collective responsibility). They had a bias toward God as ultimate giver of good health (religion) and their husbands played a dominant role in vaccination decision-making (masculinity). Mothers perceived their children vulnerable to disease outbreaks, hence, motivated vaccination (complacency). The study provided a useful qualitative tool for understanding mothers' vaccination decision-making in low resources settings.

Lipo-pam™ adjuvanted herpes zoster vaccine induces potent gE-specific cellular and humoral immune responses

Herpes zoster (HZ), also known as shingles, is caused by the reactivation of latent varicella-zoster virus (VZV). Decreased VZV-specific T-cell immune responses significantly contribute to the development of HZ. Shingrix is a recombinant zoster vaccine that is currently used to prevent HZ. However, Shingrix has high reactogenicity and pain at the injection site due to QS21, one of the adjuvant components. In this study, we developed a new herpes zoster vaccine formulation called CVI-VZV-001, containing gE protein and a novel liposome-based adjuvant Lipo-pam™, which consists of two TLR agonists. We evaluated the immunogenicity of CVI-VZV-001 in mouse and rabbit models. CVI-VZV-001 elicited robust gE-specific T-cell immune responses and gE-specific antibody production. Specifically, CVI-VZV-001 induced polyfunctional CD4+ T cell populations that secrete multiple cytokines. Furthermore, CVI-VZV-001 sustained the gE-specific immune responses for up to six months after immunization. To ensure CVI-VZV-001's safety for further development, we conducted a good laboratory practice (GLP) toxicity test, which confirmed that CVI-VZV-001 is safe for use. At present, CVI-VZV-001 is undergoing phase I clinical trials. This study suggests that CVI-VZV-001 can be a potent candidate for the HZ vaccine with high immunogenicity and safety.

Spatial distribution and determinants of measles vaccination dropout among under-five children in Ethiopia: A spatial and multilevel analysis of 2019 Ethiopian demographic and health survey

BACKGROUND

Each year, vaccine-preventable diseases cost the lives of 8.8 million under-five children. Although vaccination prevents 1-2 million childhood deaths worldwide, measles vaccination dropouts are not well studied in developing countries, particularly in Ethiopia. Therefore, this study aims to assess the spatial distribution of the measles vaccination dropout and its determinants among under-five children in Ethiopia.

METHODS

Data from Ethiopian Demographic and Health Survey 2019 was used for data analysis. The study used a total of 5,753 children. Spatial autocorrelations was used to determine the spatial dependency of measles vaccination dropout. Ordinary interpolation was employed to forecast measles vaccination dropout. Factors associated with measles vaccination dropout were declared significant at p-values <0.05. The data were interpreted using the confidence interval and adjusted odds ratio. A model with the lowest deviance and highest logliklihood ratio was selected as the best-fit model.

RESULTS

In Ethiopia, one in three under-five children had measles vaccination dropouts. Factors such as birth interval (AOR = 1.87, 95% CI: 1.30, 2.70), unmarried marital status women (AOR = 3.98, 95% CI: 1.08, 8.45), ≤1 number of under-five children (AOR = 3.86, 95% CI: 2.56, 5.81), rural place of residence (AOR = 2.43, 95% CI: 2.29, 3.11), low community-level ANC utilization (AOR = 3.20, 95% CI: 2.53, 3.56), and residing in Benishangul Gumuz (AOR = 1.80, 95% CI: 1.061, 3.06) had higher odds of measles vaccination dropout.

CONCLUSIONS

Measles vaccination dropout rates in Ethiopia among under-five children were high compared to the maximum tolerable vaccination dropout level of 10% by the WHO. Both individual and community-level variables were determinants of measles vaccination dropout. The ministry of health in Ethiopia should give attention to those mothers of under-five children who reported underutilization of ANC services and rural residences while designing policies and strategies in areas of high spatial clustering of vaccine dropout in Ethiopia.

Malaria vaccination in Africa: A mini-review of challenges and opportunities

Malaria remains an endemic public health concern in Africa, significantly contributing to morbidity and mortality rates. The inadequacies of traditional prevention measures, like integrated vector management and antimalarial drugs, have spurred efforts to strengthen the development and deployment of malaria vaccines. In addition to existing interventions like insecticide-treated bed nets and artemisinin-based combination therapies, malaria vaccine introduction and implementation in Africa could drastically reduce the disease burden and hasten steps toward malaria elimination. The malaria vaccine rollout is imminent as optimistic results from final clinical trials are anticipated. Thus, determining potential hurdles to malaria vaccine delivery and uptake in malaria-endemic regions of sub-Saharan Africa will enhance decisions and policymakers' preparedness to facilitate efficient and equitable vaccine delivery. A multisectoral approach is recommended to increase funding and resources, active community engagement and participation, and the involvement of healthcare providers.

Mitigating dengue incidence through advanced Aedes larval surveillance and control: A successful experience from Pakistan

Dengue fever is a viral disease caused by one of four dengue stereotypes (Flavivirus: Flaviviridae) that are primarily transmitted by Aedes albopictus (Skuse) and Aedes aegypti (L.). To safeguard public health, it is crucial to conduct surveys that examine the factors favouring the presence of these species. Our study surveyed 42 councils across four towns within the Bhakkar district of Punjab Province, by inspecting man-made or natural habitats containing standing water. First, door-to-door surveillance teams from the district health department were assigned to each council to surveillance Aedes species and dengue cases. Second, data collection through surveillance efforts, and validation procedures were implemented, and the verified data was uploaded onto the Dengue Tracking System by Third Party Validation teams. Third, data were analysed to identify factors influencing dengue fever cases. The findings demonstrated the following: (1) Predominantly, instances were discerned among individuals who had a documented history of having travelled beyond the confines of the province. (2) Containers associated with evaporative air coolers and tyre shops were responsible for approximately 30% of the Aedes developmental sites. (4) Variability in temperature was responsible for approximately 45% of the observed differences in the quantity of recorded Aedes mosquito developmental sites. (5) Implementation of dengue prevention initiatives precipitated a 50% reduction in Aedes-positive containers, alongside a notable 70% decline in reported cases of dengue fever during the period spanning 2019 to 2020, while the majority of reported cases were of external origin. Aedes control measures substantially curtailed mosquito populations and lowered vector-virus interactions. Notably, local dengue transmission was eliminated through advanced and effective Aedes control efforts, emphasising the need for persistent surveillance and eradication of larval habitats in affected regions.

Accelerating access for all through research and innovation in immunization: Recommendations from Strategic Priority 7 of the Immunization Agenda 2030

Research and innovation have been fundamental to many of the successes in immunization thus far, and will play important roles in the future success of Immunization Agenda 2030 (IA2030). Strategic Priority 7 (SP7) of IA2030, which addresses research and innovation, is explicitly informed by country needs and priorities, and aims to strengthen the innovation ecosystem through capacity building and collaboration at country, regional, and global levels. SP7 identifies four key focus areas: (1) "needs-based innovation", (2) "new and improved products, services, and practices", (3) "evidence for implementation", and (4) "local capacity". Strategic interventions in these key focus areas apply the lessons of the Global Vaccine Action Plan and the "Decade of Vaccines" to emphasize local innovation, promote the use of research by countries to improve program performance and impact, and encourage capacity building for the development and implementation of innovations. The proposed approach will maintain a focus on the development of new vaccines and the improvement of existing vaccines, and increase attention to innovation in service delivery. Monitoring and evaluation will foster evidence-based priority setting at the country level and help to ground the global research and development (R&D) agenda in the needs of communities. Together, these approaches are intended to harness the power of research and innovation more effectively, to meet the challenges of the future and achieve the ambitious goals of IA2030.

The Vaccine Training Barometer: Assessing healthcare providers' confidence to answer vaccine-related questions and their training needs

Healthcare providers (HCP) are seen by the public as the most trustworthy source of information about vaccination. While HCPs could be a valuable partner to increase vaccine confidence in general, it is not clear whether they feel confident themselves to address questions concerning vaccination. In the context of the EU Joint Action on Vaccination (EU-JAV), the Vaccine Training Barometer, an online survey tool, was developed to assess how frequently HCPs receive questions about vaccination, how confident they feel to answer these questions, and to what extent they are willing to follow extra training. After a pilot test in Flanders, Belgium, the Barometer was launched and completed by 833 HCPs in Flanders and 291 HCPs in the Spanish regions of Catalonia, Navarre and Valencian Community from November 2020 until January 2021, during the COVID-19 pandemic, just before and during the start of the first COVID-19 vaccination campaigns. In both countries, HCPs frequently received questions about vaccination (mostly on a daily or weekly basis), and about two thirds of them indicated that the frequency of questions had increased during the three months prior to completing the survey. Most questions were about the side effects and safety of vaccines. In both countries, a considerable proportion of HCPs did not feel confident to answer vaccine-related questions (31.5% felt confident in Flanders, 21.6% in Spain). A large proportion of HCPs received questions in the last three months before the survey that they could not answer (52.4% of respondents in Flemish sample, 41.5% in Spanish sample). Only 11.4% (Flanders) and 11.3% (Spain) of the respondents felt they gained sufficient knowledge through their standard education to be able to answer questions about vaccination. Almost all respondents were willing to follow extra training on vaccination (Flanders: 95.4%, Spain: 96.6%). The Vaccine Training Barometer is thus a useful tool to monitor HCPs' confidence to answer questions about vaccination and to capture their training needs.

Vaccination strategies impact the probability of outbreak extinction: A case study of COVID-19 transmission

Mass vaccination has proven to be an effective control measure for mitigating the transmission of infectious diseases. Throughout history, various vaccination strategies have been employed to control infections and terminate outbreaks. In this study, we utilized the transmission of COVID-19 as a case study and constructed a stochastic age-structured compartmental model to investigate the effectiveness of different vaccination strategies. Our analysis focused on estimating the outbreak extinction probability under different vaccination scenarios in both homogeneous and heterogeneous populations. Notably, we found that population heterogeneity can enhance the likelihood of outbreak extinction at varying levels of vaccine coverage. Prioritizing vaccinations for individuals with higher infection risk was found to maximize outbreak extinction probability and reduce overall infections, while allocating vaccines to those with higher mortality risk has been proven more effective in reducing deaths. Moreover, our study highlighted the significance of booster doses as the vaccine effectiveness wanes over time, showing that they can significantly enhance the extinction probability and mitigate disease transmission.

Systematic review of social determinants of childhood immunisation in low- and middle-income countries and equity impact analysis of childhood vaccination coverage in Nigeria

BACKGROUND

Nigeria has a high proportion of the world's underimmunised children. We estimated the inequities in childhood immunisation coverage associated with socioeconomic, geographic, maternal, child, and healthcare characteristics among children aged 12-23 months in Nigeria using a social determinants of health perspective.

METHODS

We conducted a systematic review to identify the social determinants of childhood immunisation associated with inequities in vaccination coverage among low- and middle-income countries. Using the 2018 Nigeria Demographic and Health Survey (DHS), we conducted multiple logistic regression to estimate the association between basic childhood vaccination coverage (1-dose BCG, 3-dose DTP-HepB-Hib (diphtheria, tetanus, pertussis, hepatitis B and Haemophilus influenzae type B), 3-dose polio, and 1-dose measles) and socioeconomic, geographic, maternal, child, and healthcare characteristics in Nigeria.

RESULTS

From the systematic review, we identified the key determinants of immunisation to be household wealth, religion, and ethnicity for socioeconomic characteristics; region and place of residence for geographic characteristics; maternal age at birth, maternal education, and household head status for maternal characteristics; sex of child and birth order for child characteristics; and antenatal care and birth setting for healthcare characteristics. Based of the 2018 Nigeria DHS analysis of 6,059 children aged 12-23 months, we estimated that basic vaccination coverage was 31% (95% CI: 29-33) among children aged 12-23 months, whilst 19% (95% CI:18-21) of them were zero-dose children who had received none of the basic vaccines. After controlling for background characteristics, there was a significant increase in the odds of basic vaccination by household wealth (AOR: 3.21 (2.06, 5.00), p < 0.001) for the wealthiest quintile compared to the poorest quintile, antenatal care of four or more antenatal care visits compared to no antenatal care (AOR: 2.87 (2.21, 3.72), p < 0.001), delivery in a health facility compared to home births (AOR 1.32 (1.08, 1.61), p = 0.006), relatively older maternal age of 35-49 years compared to 15-19 years (AOR: 2.25 (1.46, 3.49), p < 0.001), and maternal education of secondary or higher education compared to no formal education (AOR: 1.79 (1.39, 2.31), p < 0.001). Children of Fulani ethnicity in comparison to children of Igbo ethnicity had lower odds of receiving basic vaccinations (AOR: 0.51 (0.26, 0.97), p = 0.039).

CONCLUSIONS

Basic vaccination coverage is below target levels for all groups. Children from the poorest households, of Fulani ethnicity, who were born in home settings, and with young mothers with no formal education nor antenatal care, were associated with lower odds of basic vaccination in Nigeria. We recommend a proportionate universalism approach for addressing the immunisation barriers in the National Programme on Immunization of Nigeria.

Nanotechnology of inhalable vaccines for enhancing mucosal immunity

Vaccines are the cornerstone of world health. The majority of vaccines are formulated as injectable products, facing the drawbacks of cold chain transportation, needle-stick injuries, and primary systemic immunity. Inhalable vaccines exhibited unique advantages due to their small dose, easy to use, quick effect, and simultaneous induction of mucosal and systemic responses. Facing global pandemics, especially the coronavirus disease 2019 (COVID-19), a majority of inhalable vaccines are in preclinical or clinical trials. A better understanding of advanced delivery technologies of inhalable vaccines may provide new scientific insights for developing inhalable vaccines. In this review article, detailed immune mechanisms involving mucosal, cellular, and humoral immunity were described. The preparation methods of inhalable vaccines were then introduced. Advanced nanotechnologies of inhalable vaccines containing inhalable nucleic acid vaccines, inhalable adenovirus vector vaccines, novel adjuvant-assisted inhalable vaccines, and biomaterials for inhalable vaccine delivery were emphatically discussed. Meanwhile, the latest clinical progress in inhalable vaccines for COVID-19 and tuberculosis was discussed.

A Practical Guide to Full Value of Vaccine Assessments

Articulating the wide range of health, social and economic benefits that vaccines offer may help to overcome obstacles in the vaccine development pipeline. A framework to guide the assessment and communication of the value of a vaccine-the Full Value of Vaccine Assessment (FVVA)-has been developed by the WHO. The FVVA framework offers a holistic assessment of the value of vaccines, providing a synthesis of evidence to inform the public health need of a vaccine, describing the supply and demand aspects, its market and its impact from a health, financial and economic perspective. This paper provides a practical guide to how FVVAs are developed and used to support investment in vaccines, ultimately leading to sustained implementation in countries. The FVVA includes a range of elements that can be broadly categorised as synthesis, vaccine development narrative and defining vaccine impact and value. Depending on the features of the disease/vaccine in question, different elements may be emphasised; however, a standardised set of elements is recommended for each FVVA. The FVVA should be developed by an expert group who represent a range of stakeholders, perspectives and geographies and ensure a fair, coherent and evidence-based assessment of vaccine value.

Validation of a double-color ELISpot assay of IFN-γ and IL-4 production in human peripheral blood mononuclear cells

The Enzyme-Linked ImmunoSpot (ELISpot) assay detects cytokines secreted during T cell-specific immune responses against pathogens. As this assay has acquired importance in the clinical setting, standard bioanalytical evaluation of this method is required. Here, we describe a formal bioanalytical validation of a double-color ELISpot assay for the evaluation of IFN-γ and IL-4 released by T helper 1 and T helper 2 cells, respectively. As recommended by international guidelines, the parameters assessed were: range and detection limits (limit of detection, LOD; upper and lower limit of quantification, ULOQ and LLOQ), Linearity, Relative Accuracy, Repeatability, Intermediate Precision, Specificity and Robustness. The results obtained in this validation study demonstrate that this assay meets the established acceptability criteria. ELISpot is therefore a reliable technique for measuring T cell-specific immune responses against various antigens of interest.

Multiple antigen presenting system (MAPS): state of the art and potential applications

INTRODUCTION

Technological innovations have been instrumental in advancing vaccine design and protective benefit. Improvements in the safety, tolerability, and efficacy/effectiveness profiles have profoundly reduced vaccine-preventable global disease morbidity and mortality. Here we present an original vaccine platform, the Multiple Antigen Presenting System (MAPS), that relies on high-affinity interactions between a biotinylated polysaccharide (PS) and rhizavidin-fused pathogen-specific proteins. MAPS allows for flexible combinations of various PS and protein components.

AREAS COVERED

This narrative review summarizes the underlying principles of MAPS and describes its applications for vaccine design against bacterial and viral pathogens in non-clinical and clinical settings.

EXPERT OPINION

The utilization of high-affinity non-covalent biotin-rhizavidin interactions in MAPS allows for combining multiple PS and disease-specific protein antigens in a single vaccine. The modular design enables a simplified exchange of vaccine components. Published studies indicate that MAPS technology may support enhanced immunogenic breadth (covering more serotypes, inducing B- and T-cell responses) beyond that which may be elicited via PS- or protein-based conjugate vaccines. Importantly, a more detailed characterization of MAPS-based candidate vaccines is warranted, especially in clinical studies. It is anticipated that MAPS-based vaccines could be adapted and leveraged across numerous diseases of global public health importance.

Assessment of adherence to pre-vaccination precautions and AEFI reporting practices during BCG vaccination in 4 hospitals in Ghana

The BCG vaccine, like all other vaccines, is associated with adverse events following immunization (AEFI). Reducing the incidence of AEFI is crucial in reposing confidence in BCG vaccination and reducing hesitancy associated with the vaccine. This requires safety precautions before and during vaccinations, as well as reporting AEFIs after vaccination. This study assessed the adherence of health-care professionals to pre-vaccination precautions and adverse events following immunization (AEFI) reporting practices during BCG vaccination in four hospitals in Ghana. It is hoped that the findings of the study will serve as a baseline to identify gaps for further studies to generate a stronger evidence for policy formulation aimed at improving BCG vaccine safety in Ghana and other tuberculosis endemic countries. A cross-sectional study design was employed, and Statistical Package for Social Sciences, IBM® SPSS version 25 (SPSS Inc. USA) software was used for analysis. Chi-square and binary logistic regression tests were used to test the association between categorical variables and predictors of adherence to pre-BCG vaccination precautions, respectively, and a p-value of <.05 was considered statistically significant. The AEFIs commonly reported by mothers included abscess, injection site pain, injection site redness, fever, rash, muscle weakness, diarrhea, vomiting, coughing and rhinitis. Ninety-three participants (73.2%) were adherent to pre-BCG vaccination precautions. Ninety-two participants (72.4%) informed mothers to report all AEFIs encountered. Adherence to pre-BCG vaccination precautions and AEFI reporting were generally good; however, there is still room for improvement.

Memory T Cells Discrepancies in COVID-19 Patients

The immune response implicated in Coronavirus disease 2019 (COVID-19) pathogenesis remains to be fully understood. The present study aimed to clarify the alterations in CD4+ and CD8+ memory T cells' compartments in SARS-CoV-2-infected patients, with an emphasis on various comorbidities affecting COVID-19 patients. Peripheral blood samples were collected from 35 COVID-19 patients, 16 recovered individuals, and 25 healthy controls, and analyzed using flow cytometry. Significant alterations were detected in the percentage of CD8+ T cells and effector memory-expressing CD45RA CD8+ T cells (TEMRA) in COVID-19 patients compared to healthy controls. Interestingly, altered percentages of CD4+ T cells, CD8+ T cells, T effector (TEff), T naïve cells (TNs), T central memory (TCM), T effector memory (TEM), T stem cell memory (TSCM), and TEMRA T cells were significantly associated with the disease severity. Male patients had more CD8+ TSCMs and CD4+ TNs cells, while female patients had a significantly higher percentage of effector CD8+CD45RA+ T cells. Moreover, altered percentages of CD8+ TNs and memory CD8+CD45RO+ T cells were detected in diabetic and non-diabetic COVID-19 patients, respectively. In summary, this study identified alterations in memory T cells among COVID-19 patients, revealing a sex bias in the percentage of memory T cells. Moreover, COVID-19 severity and comorbidities have been linked to specific subsets of T memory cells which could be used as therapeutic, diagnostic, and protective targets for severe COVID-19.

Factors associated with recommendation behaviors of four non-National Immunization Program vaccines: a cross-sectional survey among public health workers in China

BACKGROUND

Immunization is a crucial preventive measure to safeguard children under five years old against a range of diseases. In China, the coverage rate of non-National Immunization Program (non-NIP) vaccines can be improved by leveraging the recommendation from public health workers. Hence, understanding the influencing factors of recommendation behaviors assume paramount importance. This study aims to investigate influencing factors of public health workers' recommendation behaviors towards non-NIP vaccines, with a particular emphasis on financial incentives.

METHODS

A cross-sectional survey was conducted using a multi-stage sampling method in 2019 from August to October. 627 public health workers were recruited from 148 community healthcare centers in ten provincial-level administrative divisions in China. An anonymous questionnaire was used to collect demographic information, attitudes towards vaccination, and recommendation behaviors towards non-NIP vaccines, including Haemophilus influenzae type b (Hib) vaccine, pneumococcal conjugate vaccine, varicella vaccine, and rotavirus vaccine. Descriptive analysis and multivariate logistic regression analysis were adopted in this study.

RESULTS

Of the 610 public health workers with complete survey data, 53.8%, 57.4%, 84.1%, and 54.1% often recommended Hib vaccine, pneumococcal pneumonia vaccine (PCV), varicella vaccine, and rotavirus vaccine, respectively. Logistic regression revealed that gender (Hib vaccine: OR = 0.4, 95% CI: 0.2-0.8; PCV: OR = 0.4, 95% CI: 0.2-0.8; rotavirus vaccine: OR = 0.3, 95% CI: 0.2-0.6), financial incentives for non-NIP vaccination (Hib vaccine: OR = 1.9, 95% CI: 1.1-3.6; PCV: OR = 2.1, 95% CI: 1.1-3.9; rotavirus vaccine: OR = 2.0, 95% CI: 1.1-3.8) and perception of vaccine safety (Hib vaccine: OR = 2.7, 95% CI: 1.1-7.0; PCV: OR = 3.2, 95% CI: 1.2-8.0; rotavirus vaccine: OR = 3.0, 95% CI: 1.2-7.7) were associated with public health workers' recommendation towards Hib vaccine, PCV and rotavirus vaccine.

CONCLUSIONS

The findings highlighted public health workers' recommendation behaviors of non-NIP vaccines in China and revealed strong association between vaccine recommendation and financial incentives. This highlights the importance of financial incentives in public health workers' recommendation toward non-NIP vaccines in China. Proper incentives are recommended for public health workers to encourage effective health promotion in immunization practices.

Critical success factors for high routine immunisation performance: a qualitative analysis of interviews and focus groups from Nepal, Senegal, and Zambia

OBJECTIVES

Vaccination averts an estimated 2-3 million deaths annually. Although vaccine coverage improvements across Africa and South Asia have remained below global targets, several countries have outperformed their peers with significant increases in coverage. The objective of this study was to examine these countries' vaccination programmes and to identify and describe critical success factors that may have supported these improvements.

DESIGN

Multiple case study design using qualitative research methods.

SETTING

Three countries with high routine immunisation rates: Nepal, Senegal, and Zambia.

PARTICIPANTS

We conducted 207 key informant interviews and 71 focus group discussions with a total of 678 participants. Participants were recruited from all levels, including government officials, health facility staff, frontline workers, community health workers, and parents. Participants were recruited from both urban and rural districts in Nepal, Senegal, and Zambia.

RESULTS

Our data revealed that the critical success factors for vaccination programmes relied on the cultural, historical, and statutory context in which the interventions were delivered. In Nepal, Senegal, and Zambia, high immunisation coverage was driven by (1) strong governance structures and healthy policy environments; (2) adjacent successes in health system strengthening; (3) government-led community engagement initiatives, and (4) adaptation considering contextual factors at all levels of the health system.

CONCLUSIONS

Throughout this project, our analysis returned to the importance of defining and understanding the context, governance, financing, and health systems within a country, rather than focusing on any one intervention. This paper augments findings from existing literature by highlighting how contextual factors impact implementation decisions that have led to improvements in childhood vaccine delivery. Findings from this research may help identify transferable lessons and support actionable recommendations to improve national immunisation coverage in other settings.

Multicomponent interventions to improve routine childhood vaccine uptake in low and middle-income countries: a scoping review protocol

INTRODUCTION

Vaccine coverage remains inequitable globally. Many systematic reviews have looked at the effectiveness of strategies to improve vaccine uptake; however, these reviews frequently lack data from low and middle-income countries (LMICs), where evidence of cost-effective strategies is most valuable. This is partly because reviews often exclude non-randomised, observational or unpublished evaluations that are common in LMICs. Many reviews also exclude multicomponent interventions due to challenges isolating the effect of each component. A comprehensive mapping of multicomponent interventions implemented in LMICs would increase the visibility of studies excluded from systematic reviews and improve comparability of future evaluations by providing guidance for researchers on evaluation frameworks. This scoping review aims to identify, compare and summarise the properties and evaluation methods of multicomponent interventions to improve uptake of routine childhood vaccines in LMICs, and to assess the strengths and limitations of evaluation frameworks applied.

METHODS AND ANALYSIS

This review will be conducted using the Joanna Briggs Institute methodology for scoping reviews and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses Extension for Scoping Reviews guidelines. We will search the following databases: MEDLINE, Embase, PubMed, Cochrane, Eldis and Global Health (CAB Direct), Global Index Medicus, 3ie Portal, Google Scholar, COnnecting REpositories, and reference lists. One author will screen titles and abstracts and extract data from included articles using a pretested data extraction template. Uncertainties will be resolved through discussion with another author. Only studies published in English will be included for full review. We will assess the practicability, applicability, sensitivity and specificity of the evaluation frameworks used and present results using descriptive statistics, summary tables and charts.

ETHICS AND DISSEMINATION

Ethics approval is not required. The review will be submitted as part of a doctoral thesis, presented at conferences and published in peer-reviewed journals.

STUDY REGISTRATION

https://osf.io/7r84g.

Intestinal Helminth Infection Impairs Oral and Parenteral Vaccine Efficacy

The impact of endemic parasitic infection on vaccine efficacy is an important consideration for vaccine development and deployment. We have examined whether intestinal infection with the natural murine helminth Heligmosomoides polygyrus bakeri alters Ag-specific Ab and cellular immune responses to oral and parenteral vaccination in mice. Oral vaccination of mice with a clinically relevant, live, attenuated, recombinant Salmonella vaccine expressing chicken egg OVA (Salmonella-OVA) induced the accumulation of activated, OVA-specific T effector cells rather than OVA-specific regulatory T cells in the GALT. Intestinal helminth infection significantly reduced Th1-skewed Ab responses to oral vaccination with Salmonella-OVA. Activated, adoptively transferred, OVA-specific CD4+ T cells accumulated in draining mesenteric lymph nodes of vaccinated mice, regardless of their helminth infection status. However, helminth infection increased the frequencies of adoptively transferred OVA-specific CD4+ T cells producing IL-4 and IL-10 in the mesenteric lymph node. Ab responses to the oral Salmonella-OVA vaccine were reduced in helminth-free mice adoptively transferred with OVA-specific CD4+ T cells harvested from mice with intestinal helminth infection. Intestinal helminth infection also significantly reduced Th2-skewed Ab responses to parenteral vaccination with OVA adsorbed to alum. These findings suggest that vaccine-specific CD4+ T cells induced in the context of helminth infection retain durable immunomodulatory properties and may promote blunted Ab responses to vaccination. They also underscore the potential need to treat parasitic infection before mass vaccination campaigns in helminth-endemic areas.

The Full Value of Vaccine Assessments (FVVA): a framework for assessing and communicating the value of vaccines for investment and introduction decision-making

BACKGROUND

Several economic obstacles can deter the development and use of vaccines. This can lead to limited product options for some diseases, delays in new product development, and inequitable access to vaccines. Although seemingly distinct, these obstacles are actually interrelated and therefore need to be addressed through a single over-arching strategy encompassing all stakeholders.

METHODS

To help overcome these obstacles, we propose a new approach, the Full Value of Vaccines Assessments (FVVA) framework, to guide the assessment and communication of the value of a vaccine. The FVVA framework is designed to facilitate alignment across key stakeholders and to enhance decision-making around investment in vaccine development, policy-making, procurement, and introduction, particularly for vaccines intended for use in low- and middle-income countries.

RESULTS

The FVVA framework has three key elements. First, to enhance assessment, existing value-assessment methods and tools are adapted to include broader benefits of vaccines as well as opportunity costs borne by stakeholders. Second, to improve decision-making, a deliberative process is required to recognize the agency of stakeholders and to ensure country ownership of decision-making and priority setting. Third, the FVVA framework provides a consistent and evidence-based approach that facilitates communication about the full value of vaccines, helping to enhance alignment and coordination across diverse stakeholders.

CONCLUSIONS

The FVVA framework provides guidance for stakeholders organizing global-level efforts to promote investment in vaccines that are priorities for LMICs. By providing a more holistic view of the benefits of vaccines, its application also has the potential to encourage greater take-up by countries, thereby leading to more sustainable and equitable impacts of vaccines and immunization programmes.

Dynamics of SARS-CoV-2-Specific B Cell Memory Responses in Infected and Vaccinated Individuals

Coronavirus disease 2019 (COVID-19), caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), rapidly resulted in a pandemic constituting a global health emergency. As an indicator of long-term immune protection from reinfection with the SARS-CoV-2 virus, the presence of memory B cells (MBCs) should be evaluated. Since the beginning of COVID-19 pandemic, several variants of concerns have been detected, including Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1/B.1.1.28.1), Delta (B.1.617.2), and Omicron (BA.1) variants with several different mutations, causing serious concern regarding the increased frequency of reinfection, and limiting the effectiveness of the vaccine response. At this regard, we investigated SARS-CoV-2-specific cellular immune responses in four different cohorts: COVID-19, COVID-19 infected and vaccinated, vaccinated, and negative subjects. We found that MBC response to SARS-CoV-2 at more than 11 months postinfection was higher in the peripheral blood of all COVID-19 infected and vaccinated subjects respect to all the other groups. Moreover, to better characterize the differences of SARS-CoV-2 variants immune responses, we genotyped SARS-CoV-2-positive samples from the patients' cohort. We found a higher level of immunoglobulin M+ (IgM+) and IgG+ spike MBCs in SARS-CoV-2-positive patients (5-8 months after symptoms onset) infected with the SARS-CoV-2-Delta variant compared with the SARS-CoV-2-Omicron variant implying a higher immune memory response. Our findings showed that MBCs persist more than 11 months after primary infection indicating a different involvement of the immune system according to the different SARS-CoV-2 variant that infected the host.

Individual and Work-Related Characteristics Associated with COVID-19 Vaccination Status among Ohio Nurses

Uptake of the COVID-19 vaccine by nurses lags behind that of other health care professionals with minimal empirical evidence to understand this phenomenon. In this secondary analysis, we examined nurses' individual and work-related characteristics and their association with COVID-19 vaccination status. Alumni of three Ohio nursing colleges and members of a professional organization were invited to complete questionnaires from June through August 2021. Logistic regression models were used to evaluate associations between nurse characteristics and vaccination status. Among 844 respondents, 754 (80.30%) had received at least one dose of the vaccine. Older age, having a bachelor's degree or higher, and working in critical care were associated with vaccination. Providing direct care for COVID-19 patients in the last 7 days and a higher perception of one's work being affected by COVID-19 were significantly associated with being vaccinated, whereas prior COVID-19 infection was inversely associated with vaccination status. Our findings suggest that COVID-19 vaccine uptake among nurses is influenced by a host of factors related to virus knowledge, beliefs, and risk perceptions. Awareness of these factors can aid the development of interventions to increase nurses' acceptance of vaccines.

Critical success factors for high routine immunization performance: A case study of Senegal

Background

The essential components of a vaccine delivery system are well-documented, but robust evidence is lacking on how policies and implementation strategies are operationalized to drive catalytic improvements in coverage. To address this gap, we identified success factors that supported improvements in routine immunization coverage in Senegal, especially from 2000 to 2019.

Methods

We identified Senegal as an exemplar in the delivery of childhood vaccines through analysis of DTP1 and DTP3 coverage data. Through interviews and focus group discussions at the national, regional, district, health facility, and community-level, we investigated factors that contributed to high and sustained vaccination coverage. We conducted a thematic analysis through application of implementation science frameworks to determine critical success factors. We triangulated these findings with quantitative analyses using publicly available data.

Results

The following success factors emerged: 1) Strong political will and prioritization of resources for immunization programming supported urgent allocation of funding and supplies; 2) Collaboration between the Ministry of Health and Social Action and external partners fostered innovation, capacity building, and efficiency; 3) Improved surveillance, monitoring, and evaluation allowed for timely and evidence-based decision making; 4) Community ownership of vaccine service delivery supported tailored programming and response to local needs; and 5) Community health workers spearheaded vaccine promotion and demand generation for vaccines.

Conclusion

The vaccination program in Senegal was supported by evidence-based decision making at the national-level, alignment of priorities between governmental entities and external partners, and strong community engagement initiatives that fostered local ownership of vaccine delivery and uptake. High routine immunization coverage was likely driven by prioritization of immunization programming, improved surveillance systems, a mature and reliable community health worker program, and tailored strategies for addressing geographical, social, and cultural barriers.

Local infectious disease experience influences vaccine refusal rates: a natural experiment

Vaccination has been critical to the decline in infectious disease prevalence in recent centuries. Nonetheless, vaccine refusal has increased in recent years, with complacency associated with reductions in disease prevalence highlighted as an important contributor. We exploit a natural experiment in Glasgow at the beginning of the twentieth century to investigate whether prior local experience of an infectious disease matters for vaccination decisions. Our study is based on smallpox surveillance data and administrative records of parental refusal to vaccinate their infants. We analyse variation between administrative units of Glasgow in cases and deaths from smallpox during two epidemics over the period 1900-1904, and vaccine refusal following its legalization in Scotland in 1907 after a long period of compulsory vaccination. We find that lower local disease incidence and mortality during the epidemics were associated with higher rates of subsequent vaccine refusal. This finding indicates that complacency influenced vaccination decisions in periods of higher infectious disease risk, responding to local prior experience of the relevant disease, and has not emerged solely in the context of the generally low levels of infectious disease risk of recent decades. These results suggest that vaccine delivery strategies may benefit from information on local variation in incidence.

The COVID-19 pandemic in sub-Saharan Africa: The significance of presumed immune sufficiency

A novel coronavirus known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first reported in China in 2019 and later ignited a global pandemic. Contrary to expectations, the effect of the pandemic was not as devastating to Africa and its young population compared to the rest of the world. To provide insight into the possible reasons for the presumed immune sufficiency to coronavirus disease 2019 (COVID-19) in Africa, this review critically examines literature published from 2020 onwards on the dynamics of COVID-19 infection and immunity and how other prevalent infectious diseases in Africa might have influenced the outcome of COVID-19. Studies characterising the immune response in patients with COVID-19 show that the correlates of protection in infected individuals are T-cell responses against the SARS-CoV-2 spike protein and neutralising titres of immunoglobin G and immunoglobin A antibodies. In some other studies, substantial pre-existing T-cell reactivity to SARS-CoV-2 was detected in many people from diverse geographical locations without a history of exposure. Certain studies also suggest that innate immune memory, which offers protection against reinfection with the same or another pathogen, might influence the severity of COVID-19. In addition, an initial analysis of epidemiological data showed that COVID‑19 cases were not severe in some countries that implemented universal Bacillus Calmette-Guerin (BCG) vaccination policies, thus supporting the potential of BCG vaccination to boost innate immunity. The high burden of infectious diseases and the extensive vaccination campaigns previously conducted in Africa could have induced specific and non-specific protective immunity to infectious pathogens in Africans.

The overlapping burden of the three leading causes of disability and death in sub-Saharan African children

Despite substantial declines since 2000, lower respiratory infections (LRIs), diarrhoeal diseases, and malaria remain among the leading causes of nonfatal and fatal disease burden for children under 5 years of age (under 5), primarily in sub-Saharan Africa (SSA). The spatial burden of each of these diseases has been estimated subnationally across SSA, yet no prior analyses have examined the pattern of their combined burden. Here we synthesise subnational estimates of the burden of LRIs, diarrhoea, and malaria in children under-5 from 2000 to 2017 for 43 sub-Saharan countries. Some units faced a relatively equal burden from each of the three diseases, while others had one or two dominant sources of unit-level burden, with no consistent pattern geographically across the entire subcontinent. Using a subnational counterfactual analysis, we show that nearly 300 million DALYs could have been averted since 2000 by raising all units to their national average. Our findings are directly relevant for decision-makers in determining which and targeting where the most appropriate interventions are for increasing child survival.

Critical success factors for high routine immunization performance: A case study of Nepal

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Nepal reported high and sustained immunization coverage compared to peers.

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National and multi-national partnerships supported information sharing, division of labor, and mutual capacity building.

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Pro-vaccine messaging through various mediums, including Female Community Health Volunteers, which was tailored to local needs, generated public awareness.

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Cultural values fostered collective responsibility and community ownership of vaccine coverage.

Introduction

The essential components of a vaccine delivery system are well-documented, but robust evidence on how and why the related processes and implementation strategies drive catalytic improvements in vaccination coverage are not well established. To address this gap, we identified critical success factors that may have led to substantial improvements in routine childhood immunization coverage in Nepal from 2000 through 2019.

Methods

We identified Nepal as an exemplar in the delivery of early childhood immunization through analysis of DTP1 and DTP3 coverage data. Through interviews and focus group discussions at the national, regional, district, health post, and community level, we investigated factors that contributed to high and sustained vaccine coverage. We conducted a thematic analysis through application of implementation science frameworks to determine critical success factors. We triangulated these findings with quantitative analyses using publicly available data.

Results

The following success factors emerged: 1) Codification of health as a human right, - along with other vaccine-specific legislation - ensured the stability of vaccination programming; 2) National and multi-national partnerships supported information sharing, division of labor, and mutual capacity building; 3) Pro-vaccine messaging through various mediums, which was tailored to local needs, generated public awareness; 4) Female Community Health Volunteers educated community members as trusted and compassionate neighbors; and 5) Cultural values fostered collective responsibility and community ownership of vaccine coverage.

Conclusion

This case study of Nepal suggests that the success of its national immunization program relied on the engagement and understanding of the beneficiaries. The immunization program was supported by consistent and reliable commitment, collaboration, awareness, and collective responsibility between the government, community, and partners. These networks are strengthened through a collective dedication to vaccination programming and a universal belief in health as a human right.

Coverage and Equity of Childhood Vaccines in China

IMPORTANCE

Measuring vaccination coverage rates and equity is crucial for informing immunization policies in China.

OBJECTIVES

To estimate coverage rates and multidimensional equity for childhood vaccination in China.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study was conducted via a survey in 10 Chinese provinces between August 5 and October 16, 2019, among children ages 6 months to 5 years and their primary caregivers. Children's vaccination records and their primary caregivers' demographics and socioeconomic status were collected. Data were analyzed from November 2019 to March 2022.

MAIN OUTCOMES AND MEASURES

Vaccine coverage rates were measured as a percentage of National Immunization Program (NIP) and non-NIP vaccines administered before the day on which the child was surveyed. A multidimensional equity model applied a standardized approach to ranking individuals from least to most unfairly disadvantaged by estimating differences between observed vaccination status and estimated vaccination status as function of fair and unfair variation. Fair sources of variation in coverage included whether the child was of age to receive the vaccine, and unfair sources of variation included sex of the child and sociodemographic characteristics of caregivers. Absolute equity gaps (AEGs), concentration index values, and decompositions of factors associated with vaccine equity were estimated in the model.

RESULTS

Vaccine records and sociodemographic information of 5294 children (2976 [52.8%] boys and 2498 [47.2%] girls; age range, 6-59 months; 1547 children aged 12-23 months) and their primary caregivers were collected from 10 provinces. Fully immunized coverage under the NIP was 83.1% (95% CI, 82.0%-84.1%) at the national level and more than 80% in 7 provinces (province coverage ranged from 77.8% [95% CI, 74.3% to 81.3%] in Jiangxi to 88.4% [95% CI, 85.7%-91.1%] in Beijing). For most non-NIP vaccines, however, coverage rates were less than 50%, ranging from 1.8% (95% CI, 1.3%-2.2%) for the third dose of rotavirus vaccine to 67.1% (65.4% to 68.8%) for the first dose of the varicella vaccine. The first dose of Haemophilus influenzae type b vaccine had the largest AEG, at 0.603 (95% CI, 0.570-0.636), and rotavirus vaccine dose 3 had the largest concentration index value, at 0.769 (95% CI, 0.709-0.829). The largest share of non-NIP vaccine inequity was contributed by monthly family income per capita, followed by education level, place of residence, and province for caregivers. For example, the proportion of explained inequity for pneumococcal conjugate vaccine dose 3 was 40.94% (95% CI, 39.49%-42.39%), 22.67% (95% CI, 21.43%-23.9%), 27.15% (95% CI, 25.84%-28.46%), and 0.68% (95% CI, 0.44%-0.92%) for these factors, respectively.

CONCLUSIONS AND RELEVANCE

This cross-sectional study found that NIP vaccination coverage in China was high but there was inequity for non-NIP vaccines. These findings suggest that improvements in equitable coverage of non-NIP vaccination may be urgently needed to meet national immunization goals.

Parental preference for Haemophilus influenzae type b vaccination in Zhejiang Province, China: A discrete choice experiment

Background

China is the only country in the world that has not included the Haemophilus influenzae type b (Hib) vaccine in its National Immunization Program, making it more difficult to eliminate Hib-related diseases through Hib vaccination. It is necessary to study parental preferences for Hib vaccination to optimize vaccine promotion strategies in China.

Objective

This study aimed to investigate Chinese parental preference for five attributes of Hib vaccination, i.e., the place of origin, effectiveness, adverse event, doctors' recommendation, and the price of full vaccination when making a decision to vaccinate their children under 2 years old.

Methods

A cross-sectional survey was conducted in two cities in Zhejiang Province from November to December in 2020 using a discrete choice experiment (DCE). A mixed logit model was used to estimate participating parents' preference for Hib vaccination attributes included in the DCE. Subgroup analysis and probability analysis were also conducted to capture the heterogeneity and trade-off of parental preference for Hib vaccination.

Results

Data from 6,168 observations were included in the analyses. Parents of children are, on average, more likely to voice a positive preference for Hib vaccination. Such attributes of Hib vaccination as effectiveness and doctor's recommendation have a significant positive influence on parents' preference for Hib vaccination, while imported vaccines, adverse events, and the price of full vaccination have a significant negative influence on parents' preference. Parents with different demographic characteristics also existed heterogeneities in preference for Hib vaccination. Parents will make a trade-off on price if the Hib vaccine has a good performance on effectiveness and safety.

Conclusion

The study found that, regardless of the place of origin of the Hib vaccine, parents with children under 2 years old prefer to compromise on price if the vaccine has a better effectiveness and safety profile. A proactive recommendation from doctors would strengthen their willingness for Hib vaccination. These findings help aid the development of communication strategies with parents for Hib vaccination in China.

Immune response induced by novel coronavirus infection

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus (SARS-CoV)-2 has been prominent around the world since it was first discovered, affecting more than 100 million people. Although the symptoms of most infected patients are not serious, there is still a considerable proportion of patients who need hospitalization and even develop fatal symptoms such as cytokine storms, acute respiratory distress syndrome and so on. Cytokine storm is usually described as a collection of clinical manifestations caused by overactivation of the immune system, which plays an important role in tissue injury and multiorgan failure. The immune system of healthy individuals is composed of two interrelated parts, the innate immune system and the adaptive immune system. Innate immunity is the body's first line of defense against viruses; it can quickly perceive viruses through pattern recognition receptors and activate related inflammatory pathways to clear pathogens. The adaptive immune system is activated by specific antigens and is mainly composed of CD4+ T cells, CD8+ T cells and B cells, which play different roles in viral infection. Here, we discuss the immune response after SARS-CoV-2 infection. In-depth study of the recognition of and response of innate immunity and adaptive immunity to SARS-CoV-2 will help to prevent the development of critical cases and aid the exploration of more targeted treatments.

The Immune Signatures data resource, a compendium of systems vaccinology datasets

Vaccines are among the most cost-effective public health interventions for preventing infection-induced morbidity and mortality, yet much remains to be learned regarding the mechanisms by which vaccines protect. Systems immunology combines traditional immunology with modern 'omic profiling techniques and computational modeling to promote rapid and transformative advances in vaccinology and vaccine discovery. The NIH/NIAID Human Immunology Project Consortium (HIPC) has leveraged systems immunology approaches to identify molecular signatures associated with the immunogenicity of many vaccines. However, comparative analyses have been limited by the distributed nature of some data, potential batch effects across studies, and the absence of multiple relevant studies from non-HIPC groups in ImmPort. To support comparative analyses across different vaccines, we have created the Immune Signatures Data Resource, a compendium of standardized systems vaccinology datasets. This data resource is available through ImmuneSpace, along with code to reproduce the processing and batch normalization starting from the underlying study data in ImmPort and the Gene Expression Omnibus (GEO). The current release comprises 1405 participants from 53 cohorts profiling the response to 24 different vaccines. This novel systems vaccinology data release represents a valuable resource for comparative and meta-analyses that will accelerate our understanding of mechanisms underlying vaccine responses.

Ensuring vaccine potency and availability: how evidence shaped Gavi's Immunization Supply Chain Strategy

Background

In 2014, Gavi and partners developed a global Immunization Supply Chain (iSC) Strategy, 2015–2020, which prioritized functioning cold chain equipment (CCE) and additional storage capacity. In 2016, Gavi launched the Cold Chain Equipment Optimization Platform (CCEOP) as a funding mechanism to improve CCE availability. In 2018, Gavi commissioned an evaluation of CCEOP in Guinea, Kenya and Pakistan. The global iSC Strategy has recently been revised, drawing on findings from effective vaccine management assessments and practical experiences. This case study presents the CCEOP evaluation and how its findings reinforced the revision of the iSC strategy.

Methods

The CCEOP evaluation used a prospective mixed-methods research design in all three countries involving key informant interviews at multiple levels of the health system, document reviews, direct observation (as and when possible), and a health facility assessment.

Results

Results show that CCEOP was effective at increasing the number of available and reliable CCE, and establishing improved management processes using the project management team (PMT) approach for country management systems and the service bundle provider approach for installation and maintenance. CCEOP also extended the iSC and immunization services in countries. The evaluation results also show gaps in the overall supply chain system, including CCE maintenance.

Discussion

Gavi has recently revised its iSC strategy, which has addressed gaps identified through assessments and practical experiences from stakeholders. Results of the CCEOP evaluation reinforce many of these findings. The strategy now provides more emphasis on supporting the fundamental infrastructure and establishing strong processes for maintenance. It also emphasizes strategic planning and forward thinking for iSC decisions, building on the processes established for the PMT through CCEOP. The original iSC strategy was an impetus for the establishment of CCEOP. The new strategy reflects shifting trends and priorities to fill gaps identified through practical experience, advocated for by stakeholders and thought leaders engaged in the iSC, and validated by the evaluation. It demonstrates the importance of aligning stakeholders with clear objectives and a sound strategy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-022-08616-9.

Conformation-Stabilized Amorphous Nanocoating for Rational Design of Long-Term Thermostable Viral Vaccines

Despite the great potency of vaccines to combat infectious diseases, their global use is hindered by a lack of thermostability, which leads to a constant need for cold-chain storage. Here, aiming at long-term thermostability and eliminating cold-chain requirements of bioactive vaccines, we propose that efforts should focus on tailoring the conformational stability of vaccines. Accordingly, we design a nanocoating composed of histidine (His)-coordinated amorphous Zn and 2-methylimidazolate complex (His-aZn-mIM) on single nanoparticles of viral vaccines to introduce intramolecular coordinated linkage between viruses and the nanocoatings. The coordinated nanocoating enhances the rigidity of proteins and preserves the vaccine's activity. Importantly, integrating His into the original Zn-N coordinative environment symbiotically reinforces its tolerance to biological and hydrothermal solutions, resulting in the augmented thermostability following the Hofmeister effect. Thus, even after storage of His-aZn-mIM encapsulated Human adenovirus type 5 (Ad5@His-aZn-mIM) at 25 °C for 90 d, the potency loss of the coated Ad5 is less than 10%, while the native Ad5 becomes 100% ineffective within one month. Such a nanocoating gains thermostability by forming an ultrastable hydration shell, which prevents viral proteins from unfolding under the attack of hydration ions, providing a conformational stabilizer upon heat exposure. Our findings represent an easy-access biomimetic platform to address the long-term vaccine storage without the requirement of a cold chain.

Vaccine Coverage in Children Younger Than 1 Year of Age during Periods of High Epidemiological Risk: Are We Preparing for New Outbreaks?

Background: According to WHO, infectious disease control can be achieved if the vaccine coverage (VC) exceeds 90%. In recent years there has been a declining trend in VC which could lead to the recurrence of infectious diseases. Objectives: The study analyzed the determinants of VC and of parental decisions regarding immunization in children aged 0−1 year monitored during two high-risk epidemiological periods (the measles epidemic and the COVID-19 pandemic period). Methods: A retrospective observational cohort study-data regarding vaccination of children younger than 1 year of age during the periods January 2019−June 2019 (measles epidemic) and January 2020−June 2020 (COVID-19 pandemic) were analyzed. 2.850 children from 2019 and 2.823 children from 2020 were enrolled. Family physicians interacted with 2840 parents or legal guardians in 2019 and with 2800 parents or legal guardians in 2020, during the infants’ consults providing medical information and answer to their questions and worries regarding their immunization. Data on immunization schedules on the determinants of parents’ decisions regarding vaccination were evaluated. Results: During 2019−2020, VC has followed a declining trend for each type of vaccine included in the Romanian National Immunization Program; the most affected were infants aged 9−12 months during both periods: in 9-month aged infants, the MMR vaccine VC was 67.49% in 2019 vs. 59.04% in 2020 (p < 0.004). In the 12 months aged infants, the MMR VC was 64.29% in 2019 vs. 55.88% in 2020 (p < 0.005). For the Hexavalent vaccine administered at the age of 11 months, the VC was 71.59% in 2019 vs. 62.08% in 2020 (p < 0.001). The determinants of parents’ decisions regarding vaccination included parental hesitance 2019—25% vs. 2020—35%, fear on side effects 2019—32% vs. 2020—45%, vaccination denial 2019—7% vs. 2020—10%. Conclusion: We found a declining trend in the VC in Romania during the epidemic and pandemic periods. The decrease in VC for MMR generated a major risk for new measles outbreaks Permanent awareness educational campaigns regarding infectious disease risk are needed, accompanied by the empowerment of primary care and the emergence of an immunization management program based on national regulatory legislation.

Understanding drivers of vaccine hesitancy among pregnant women in Nigeria: A longitudinal study

Vaccine-preventable-diseases are major contributors to disease burden in Sub-Saharan Africa. There is dearth of knowledge on the drivers of childhood vaccine hesitancy in Nigeria and its impact on coverage. Although understudied, pregnant women are a particularly important vulnerable group and very relevant for childhood vaccination decisions. This study’s aims are to adapt Confidence, Complacency, Constraints, Calculation, and Collective Responsibility, also known as the 5C psychological antecedence scale for the Nigerian context and to measure predictors of intention to vaccinate among pregnant women (prenatal) and subsequent vaccination behavior (postnatal). It is a longitudinal study that used multi-stage sampling procedure. One healthcare facility was selected from each district in five regional clusters, from which 255 pregnant women were randomly drawn. A standardized questionnaire was used to collect relevant data, including the 5C and some additional variables. Multiple linear regression using backward elimination analysis was performed to identify intention at prenatal and behavior at postnatal. Pregnant women’s intention to vaccinate unborn children was lower if they were Muslims, had lower confidence in public health system, if husband approval was important, and if they believed in rumor. At postnatal, vaccination behavior was more likely to follow mothers’ religious beliefs, when confidence in vaccine effectiveness was high and when mothers felt responsible for the collective. However, everyday stress (constraints) related to less vaccination behavior, and intention did not predict actual vaccination behavior. The 5C scale needs revision before being widely used in Nigeria. Yet, it is a better tool for measuring vaccination behavior than intention.

A Precision Adjuvant Approach to Enhance Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Vaccines Optimized for Immunologically Distinct Vulnerable Populations

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has caused significant mortality, especially among older adults whose distinct immune system reflects immunosenescence. Multiple SARS-CoV-2 vaccines have received emergency use authorization and/or licensure from the US Food and Drug Administration and throughout the world. However, their deployment has heighted significant limitations, such by age-dependent immunogenicity, requirements for multiple vaccine doses, refrigeration infrastructure that is not universally available, as well as waning immunity. Thus, there was, and continues to be a need for continued innovation during the pandemic given the desire for dose-sparing, formulations stable at more readily achievable temperatures, need for robust immunogenicity in vulnerable populations, and development of safe and effective pediatric vaccines. In this context, optimal SARS-CoV-2 vaccines may ultimately rely on inclusion of adjuvants as they can potentially enhance protection of vulnerable populations and provide dose-sparing effects enabling single shot protection.

Immune defects associated with lower SARS-CoV-2 BNT162b2 mRNA vaccine response in elderly people

The immune factors associated with impaired SARS-CoV-2 vaccine response in the elderly are mostly unknown. We studied >60 and <60 years old people vaccinated with SARS-CoV-2 BNT162b2 mRNA before and after the first and second dose. Aging was associated with a lower anti-RBD IgG levels and a decreased magnitude and polyfunctionality of SARS-CoV-2 specific T cell response. The dramatic decrease in thymic function in aged people with >60 years of age, which fueled alteration in T cell homeostasis, and lower CD161+ T cell levels were associated with decreased T cell response two months after vaccination. Additionally, a deficient dendritic cell (DC) homing, activation and Toll like receptor (TLR)-mediated function, along with a proinflammatory functional profile in monocytes, were observed in the >60 years old group, which was also related to lower specific T cell response after vaccination. These findings might be relevant for the improvement of the current vaccination strategies and for the development of new vaccine prototypes.

Microneedle-based two-step transdermal delivery of Langerhans cell-targeting immunoliposomes induces a Th1-biased immune response

Novel Coronavirus is affecting human's life globally and vaccines are one of the most effective ways to combat the epidemic. Transcutaneous immunization based on microneedle (MN) has attracted much attention because of its painlessness, rapidity, high efficiency and good compliance. In this study, CD11c monoclonal antibody-immunoliposomes (OVA@CD11c-ILP) actively targeting to Langerhans cells (LCs) were successfully prepared and were delivered by the microchannels of skin produced by MN to induce an immune response in vivo. OVA@CD11c-ILP could be targeted to LCs by conjugating CD11c monoclonal antibody to the surface of the ILP. OVA@CD11c-ILP promoted the maturation of dendritic cells (DCs) and the uptake and endocytosis of antigen by LCs. Moreover, OVA@CD11c-ILP immunization can significantly inhibit tumor growth and prolong overall survival. Furthermore, a higher antibody's titer ratio of IgG1/IgG2a indicated that the immune response stimulated by this immunization method was Th1-biased and the liposomes showed Th1-type adjuvant effect. In conclusion, the combination delivery system of immunoliposomes and microneedle can significantly improve the efficiency of antigen presentation and effectively activate cellular immune responses in the body, which is expected to be a promising transdermal immune strategy.

Critical success factors for routine immunization performance: A case study of Zambia 2000 to 2018

Introduction

The essential components of a vaccine delivery system are well-documented, but robust evidence on how and why the related processes and implementation strategies prove effective at driving coverage is not well-established. To address this gap, we identified critical success factors associated with advancing key policies and programs that may have led to the substantial changes in routine childhood immunization coverage in Zambia between 2000 and 2018.

Methods

We identified Zambia as an exemplar in the delivery of childhood vaccines through analysis of DTP1 and DTP3 coverage data. Through interviews and focus group discussions at the national and subnational levels, we investigated factors that contributed to high and sustained vaccination coverage. We conducted a thematic analysis through application of implementation science frameworks to determine critical success factors. We triangulated these findings with quantitative analyses using publicly available data.

Results

The following success factors emerged: 1) the Inter-agency Coordinating Committee was strengthened for long-term engagement which, complemented by the Zambia Immunization Technical Advisory Group, is valued by the government and integrated into national-level decision-making; 2) the Ministry of Health improved the coordination of data collection and review for informed decision-making across all levels; 3) Regional multi-actor committees identified development priorities, strategies, and funding, and iteratively adjusted policies to account for facilitators, barriers, and lessons learned; 4) Vaccine messaging was disseminated through multiple channels, including the media and community leaders, increasing trust in the government by community members; 5) The Zambia Ministry of Health and Churches Health Association of Zambia formalized a long-term organizational relationship to leverage the strengths of faith-based organizations; and 6) Neighborhood Health Committees spearheaded community-driven strategies via community action planning and ultimately strengthened the link between communities and health facilities.

Conclusion

Broader health systems strengthening and strong partnerships between various levels of the government, communities, and external organizations were critical factors that accelerated vaccine coverage in Zambia. These partnerships were leveraged to strengthen the overall health system and healthcare governance.

The Addis Declaration on Immunization: A binding reminder of the political support needed to achieve universal immunization in Africa

While African countries have improved access to immunization since the start of the millennium, progress has stagnated in the last few years. One in five African children is not vaccinated with life-saving vaccines, and recent outbreaks of vaccine-preventable diseases (VPDs) including yellow fever, measles, and meningitis, among others point to gaps in immunization coverage as well as disease surveillance. In 2017, African Heads of State endorsed the Addis Declaration on Immunization (ADI) at the 28th African Union Summit and committed to ensuring universal access to immunization across the continent. Since then, countries have taken several steps to translate the ADI commitments into tangible progress. However, the continent continues to face challenges in delivering immunization services, including limited vaccine-related funding, inequitable access to immunization services and weak surveillance systems. In the absence of concerted political will, COVID-19 threatens to reverse progress made so far. This paper reflects on the effects of political will in shaping the immunization agenda on the continent and the continued need for political commitment to deliver on the ADI commitments in a post-COVID world. Data were gathered from the regular national immunization reports, WHO/UNICEF estimates of immunization coverage as well as case studies of country implementation on ADI.

Vaccines and the social amplification of risk

In 2019, the World Health Organization (WHO) named "Vaccine Hesitancy" one of the top 10 threats to global health. Shortly afterward, the COVID-19 pandemic emerged as the world's predominant health concern. COVID-19 vaccines of several types have been developed, tested, and partially deployed with remarkable speed; vaccines are now the primary control measure and hope for a return to normalcy. However, hesitancy concerning these vaccines, along with resistance to masking and other control measures, remains a substantial obstacle. The previous waves of vaccine hesitancy that led to the WHO threat designation, together with recent COVID-19 experience, provide a window for viewing new forms of social amplification of risk (SAR). Not surprisingly, vaccines provide fertile ground for questions, anxieties, concerns, and rumors. These appear in new globalized hyperconnected communications landscapes and in the context of complex human (social, economic, and political) systems that exhibit evolving concerns about vaccines and authorities. We look at drivers, impacts, and implications for vaccine initiatives in several recent historical examples and in the current efforts with COVID-19 vaccination. Findings and insights were drawn from the Vaccine Confidence Project's decade long monitoring of media and social media and its related research efforts. The trends in vaccine confidence and resistance have implications for updating the social amplification of risk framework (SARF); in turn, SARF has practical implications for guiding efforts to alleviate vaccine hesitancy and to mitigate harms from intentional and unintentional vaccine scares.

Immunization of Rabbits with a Quadrivalent Shigella Bioconjugate Vaccine Induces Functional Antibodies Reactive with Shigella Isolates from Kenya

Diarrheal diseases are a leading cause of global morbidity and mortality, disproportionately affecting children in resource-limited settings. Although improvements in hygiene and access to clean water are helpful, vaccines are considered essential due to the low infectious dose of Shigella species and increasing antibiotic resistance. Building on achievements with conjugate vaccines, a safe and immunogenic novel bioconjugate vaccine linking Shigella O-antigen to Pseudomonas aeruginosa exoprotein A has been developed to induce immunity against Shigella flexneri 2a, 3a, and 6 and S. sonnei. This study evaluated the breadth of reactivity and functionality of pooled serum from rabbits immunized with monovalent and quadrivalent Shigella bioconjugates formulated with or without an adjuvant against Shigella serotypes isolated in Kenya. Rabbit sera were assayed by colony blot for reactivity with 67 isolates of Shigella serotypes targeted by the vaccine, S. flexneri (2a, 3a, and 6) and S. sonnei, and 42 isolates of Shigella serotypes not targeted by the vaccine, S. flexneri (1b, 2b, 4a, and 4b), S. boydii, and S. dysenteriae. Shigella isolates testing positive in the colony blot assay were then used to assess functional activity using a bactericidal assay. Of the 41 Shigella isolates targeted by the vaccine, 22 were reactive with the adjuvanted quadrivalent and the respective monovalent rabbit sera. The S. flexneri 2a and 3a monovalent rabbit serum cross-reacted with S. flexneri 3a, 2b, and 2a, respectively. Immunization with the adjuvanted quadrivalent vaccine also induced cross-reactivity with isolates of S. flexneri 2b, 4a, and 4b. Collectively, these results suggest that the Shigella quadrivalent vaccine may be more broadly protective than designed, offering a promising solution to Shigella infections.

IMPORTANCE Diarrheal diseases are the third leading cause of death globally, disproportionally affecting low- to middle-income countries like Kenya, with Shigella species being the leading cause of bacterial diarrhea, especially in children. The low infectious dose and high antibiotic resistance levels complicate treatment, leading to long-term sequelae that necessitate control measures such as vaccines to reduce morbidity and mortality rates, especially among children under 5 years of age. A quadrivalent bioconjugate Shigella vaccine was recently developed to safely and effectively induce immunity against four important Shigella spp. This study demonstrates the breadth of reactivity and functionality of the parenterally administered bioconjugate vaccine by evaluating the ability of rabbit sera to bind and kill Shigella isolates recently collected in Kenya. These results suggest that the Shigella quadrivalent vaccine may be more broadly protective than designed and may offer a promising solution to the morbidity and mortality associated with Shigella infections.

Immunization with CSP and a RIG-I Agonist is Effective in Inducing a Functional and Protective Humoral Response Against Plasmodium

Malaria is a major public health concern, as a highly effective human vaccine remains elusive. The efficacy of a subunit vaccine targeting the most abundant protein of the sporozoite surface, the circumsporozoite protein (CSP) has been hindered by difficulties in generating an effective humoral response in both quantity and quality. Using the rodent Plasmodium yoelii model we report here that immunization with CSP adjuvanted with 5’ppp-dsRNA, a RIG-I agonist, confers early and long-lasting sterile protection in mice against stringent sporozoite and mosquito bite challenges. The immunization induced high levels of antibodies, which were functional in targeting and killing the sporozoites and were sustained over time through the accumulation of long-lived plasma cells in the bone marrow. Moreover, 5’ppp-dsRNA-adjuvanted immunization with the CSP of P. falciparum was also significantly protective against challenges using a transgenic PfCSP-expressing P. yoelii parasite. Conversely, using the TLR3 agonist poly(A:U) as adjuvant resulted in a formulation that despite inducing high antibody levels was unable to generate equally functional antibodies and was, consequently, less protective. In conclusion, we demonstrate that using 5’ppp-dsRNA as an adjuvant to vaccines targeting CSP induces effective anti-Plasmodium humoral immunity.

Building the concept for WHO Evidence Considerations for Vaccine Policy (ECVP): Tuberculosis vaccines intended for adults and adolescents as a test case

Currently, no formal mechanisms or systematic approaches exist to inform developers of new vaccines of the evidence anticipated to facilitate global policy recommendations, before a vaccine candidate approaches regulatory approval at the end of pre-licensure efficacy studies. Consequently, significant delays may result in vaccine introduction and uptake, while post-licensure data are generated to support a definitive policy decision. To address the uncertainties of the evidence-to-recommendation data needs and to mitigate the risk of delays between vaccine recommendation and use, WHO is evaluating the need for and value of a new strategic alignment tool: Evidence Considerations for Vaccine Policy (ECVP). EVCPs aim to fill a critical current gap by providing early (pre-phase 3 study design) information on the anticipated clinical trial and observational data or evidence that could support WHO and/or policy decision making for new vaccines in priority disease areas. The intent of ECVPs is to inform vaccine developers, funders, and other key stakeholders, facilitating stakeholder alignment in their strategic planning for late stage vaccine development. While ECVPs are envisaged as a tool to support dialogue on evidence needs between regulators and policy makers at the national, regional and global level, development of an ECVP will not preclude or supersede the independent WHO's Strategic Advisory Group of Experts on Immunization (SAGE) evidence to recommendation (EtR) process that is required for all vaccines seeking WHO policy recommendation. Tuberculosis (TB) vaccine candidates intended for use in the adolescent and adult target populations comprise a portfolio of priority vaccines in late-stage clinical development. As such, TB vaccines intended for use in this target population provide a 'test case' to further develop the ECVP concept, and develop the first WHO ECVP considerations guidance.

Characterization of memory T cell subsets and common γ-chain cytokines in convalescent COVID-19 individuals

T cells are thought to be an important correlates of protection against SARS‐CoV2 infection. However, the composition of T cell subsets in convalescent individuals of SARS‐CoV2 infection has not been well studied. The authors determined the lymphocyte absolute counts, the frequency of memory T cell subsets, and the plasma levels of common γ−chain in 7 groups of COVID‐19 individuals, based on days since RT‐PCR confirmation of SARS‐CoV‐2 infection. The data show that both absolute counts and frequencies of lymphocytes as well as, the frequencies of CD4⁺ central and effector memory cells increased, and the frequencies of CD4⁺ naïve T cells, transitional memory, stem cell memory T cells, and regulatory cells decreased from Days 15–30 to Days 61–90 and plateaued thereafter. In addition, the frequencies of CD8⁺ central memory, effector, and terminal effector memory T cells increased, and the frequencies of CD8⁺ naïve cells, transitional memory, and stem cell memory T cells decreased from Days 15–30 to Days 61–90 and plateaued thereafter. The plasma levels of IL‐2, IL‐7, IL‐15, and IL‐21—common γc cytokines started decreasing from Days 15–30 till Days 151–180. Severe COVID‐19 patients exhibit decreased levels of lymphocyte counts and frequencies, higher frequencies of naïve cells, regulatory T cells, lower frequencies of central memory, effector memory, and stem cell memory, and elevated plasma levels of IL‐2, IL‐7, IL‐15, and IL‐21. Finally, there was a significant correlation between memory T cell subsets and common γc cytokines. Thus, the study provides evidence of alterations in lymphocyte counts, memory T cell subset frequencies, and common γ−chain cytokines in convalescent COVID‐19 individuals.

Replacing vaccine paper package inserts: a multi-country questionnaire study on the acceptability of an electronic replacement in different target groups

Background

In the European Union it is mandatory to include paper package leaflets (PPL) with all medicines, including vaccines, to inform the recipient. However, it is difficult to meet the necessity for localized PPLs in each of the 24 official European languages. Replacing PPLs with electronic versions offers many advantages including redistribution across nations, reduced storage space, accessibility by the visually impaired, easily updated information or the addition of video content. We wanted to assess the attitudes of patients (vaccine recipients or their parents) to the potential of replacing PPL with electronic versions.

Methods

We surveyed vaccinees or their parents in four European countries—Belgium, Italy, Bulgaria and France—for their actual use of vaccine PPLs and their opinions about switching to an electronic package leaflet. Our survey was conducted online because of the COVID-19 pandemic and resulted in 2518 responses to a questionnaire targeted at three specific groups with particular information needs: parents of young children, pregnant women and the elderly (≥ 60 years).

Results

Our main findings are that currently vaccine PPLs are rarely used and frequently unavailable for the vaccinee. Across the four countries surveyed 55–82% of vaccinees would accept an electronic version, as did 64% when there was an option to request a printout of the leaflet.

Conclusions

We found that switching to electronic versions of vaccine PPLs is an acceptable alternative for the public, potentially increasing the quality and amount of information reaching vaccinees while eliminating some barriers to redistribution of vaccines between countries.

Trends of the Global, Regional, and National Incidence of Measles, Vaccine Coverage, and Risk Factors in 204 Countries From 1990 to 2019

Background

Measles is a highly contagious disease that has caused global morbidity and mortality. Though great progress has been made in measles elimination, the resurgence of measles has been observed in recent years. As extant literature were mainly confined to data of local area, we conducted a systematic analysis to explore the trends of the incidence of measles, coverage rate, and the risk factors from 1990 to 2019 on global, regional, and national levels.

Methods

Data on cases of incidence, age standardized rate (ASR), vaccine coverage, and risk factors of measles were retrieved from the Global Burden of Disease (GBD) Study 2019 database. Estimated averaged percentage change (EAPC) of ASR was calculated to quantify the trends of measles incidence. Pearson correlation was applied to assess the association of EAPC and measles-containing vaccine coverage rate with socio-demographic index (SDI) in 2019, and the correlation between ASR and measles-containing vaccine coverage rate.

Results

Globally, there was a significant decrease in the number (84.18%) and ASR (6.13%, 95% CI: 5.41–6.84%) of measles incidence from 1990 to 2019. More than 80% of incidence cases were attributed to children under 5 and the proportion was highest in low SDI region. Countries and territories with low ASRs are mostly clustered in North America, Southern Latin America, and Western Europe, whereas those with high ASRs are mainly clustered in Africa, East Asia, and South Asia. Lower SDI was associated with higher ASR and lower vaccine coverage rate. The more the SDI value was further away from 0.6, the smaller the absolute value did EAPC have. Child wasting accounted for the most measles-related death cases, followed by child underweight, child stunting, and vitamin A deficiency.

Conclusions

Measles eradication is feasible, but urgently demands political commitment, financial support, and public engagement. In the context of COVID-19 pandemic and the global resurgence of measles, surveillance systems and routine immunization programs should be improved, while vaccine hesitancy needs to be addressed.