Vaccines against poverty

Global Streptococcus pyogenes strain diversity, disease associations, and implications for vaccine development: a systematic review

The high strain diversity of Streptococcus pyogenes serves as a major obstacle to vaccine development against this leading global pathogen. We did a systematic review of studies in PubMed, MEDLINE, and Embase that reported the global distribution of S pyogenes emm-types and emm-clusters from Jan 1, 1990, to Feb 23, 2023. 212 datasets were included from 55 countries, encompassing 74 468 bacterial isolates belonging to 211 emm-types. Globally, an inverse correlation was observed between strain diversity and the UNDP Human Development Index (HDI; r=-0·72; p<0·0001), which remained consistent upon subanalysis by global region and site of infection. Greater strain diversity was associated with a lower HDI, suggesting the role of social determinants in diseases caused by S pyogenes. We used a population-weighted analysis to adjust for the disproportionate number of epidemiological studies from high-income countries and identified 15 key representative isolates as vaccine targets. Strong strain type associations were observed between the site of infection (invasive, skin, and throat) and several streptococcal lineages. In conclusion, the development of a truly global vaccine to reduce the immense burden of diseases caused by S pyogenes should consider the multidimensional diversity of the pathogen, including its social and environmental context, and not merely its geographical distribution.

Public-private partnerships influencing the initiation and duration of clinical trials for neglected tropical diseases

Public-private partnerships (PPPs) for neglected tropical diseases (NTDs) are often studied as an organizational form that facilitates the management and control of the huge costs of drug research and development. Especially the later stages of drug development, including clinical trials, become very expensive. This present study investigates whether and how the type of PPPs influences the initiation and duration of NTD clinical trials. Using the ClinicalTrials.gov database, a dataset of 1175 NTD clinical studies that started between 2000 and 2021 is analyzed based on affiliation information and project duration. For the NTD clinical trials that resulted from PPPs, the collaborating types were determined and analyzed, including the public sector-, private sector-, governmental sector-, and nongovernmental organization-led collaborations. The determinants for the discontinuation of all stopped clinical trials were categorized into scientific-, funding-, political-, and logistic dimensions. The results reveal that public sector-led PPPs were the most common collaborative types, and logistic and scientific issues were the most frequent determinants of stopped clinical trials. Trial registration: ClinicalTrials.gov.

The Case for Human Challenge Trials in COVID-19

The COVID-19 pandemic has necessitated rapid research to aid in the understanding of the disease and the development of novel therapeutics. One option is to conduct controlled human infection trials (CHITs). In this article I examine the history of deliberate human infection and CHITs and their utilization prior to the COVID-19 pandemic, key ethical considerations of CHITs in the COVID-19 setting, an analysis of the World Health Organization's (WHO) Key criteria for the ethical acceptability of COVID-19 human challenge studies, and a review of the two COVID-19 CHITs that have already commenced, their compliance with the WHO criteria and other ethical considerations.

M cell maturation and cDC activation determine the onset of adaptive immune priming in the neonatal Peyer's patch

Early-life immune development is critical to long-term host health. However, the mechanisms that determine the pace of postnatal immune maturation are not fully resolved. Here, we analyzed mononuclear phagocytes (MNPs) in small intestinal Peyer's patches (PPs), the primary inductive site of intestinal immunity. Conventional type 1 and 2 dendritic cells (cDC1 and cDC2) and RORgt+ antigen-presenting cells (RORgt+ APC) exhibited significant age-dependent changes in subset composition, tissue distribution, and reduced cell maturation, subsequently resulting in a lack in CD4+ T cell priming during the postnatal period. Microbial cues contributed but could not fully explain the discrepancies in MNP maturation. Type I interferon (IFN) accelerated MNP maturation but IFN signaling did not represent the physiological stimulus. Instead, follicle-associated epithelium (FAE) M cell differentiation was required and sufficient to drive postweaning PP MNP maturation. Together, our results highlight the role of FAE M cell differentiation and MNP maturation in postnatal immune development.

Toward a Shigella Vaccine: Opportunities and Challenges to Fight an Antimicrobial-Resistant Pathogen

Shigellosis causes more than 200,000 deaths worldwide and most of this burden falls on Low- and Middle-Income Countries (LMICs), with a particular incidence in children under 5 years of age. In the last decades, Shigella has become even more worrisome because of the onset of antimicrobial-resistant strains (AMR). Indeed, the WHO has listed Shigella as one of the priority pathogens for the development of new interventions. To date, there are no broadly available vaccines against shigellosis, but several candidates are being evaluated in preclinical and clinical studies, bringing to light very important data and information. With the aim to facilitate the understanding of the state-of-the-art of Shigella vaccine development, here we report what is known about Shigella epidemiology and pathogenesis with a focus on virulence factors and potential antigens for vaccine development. We discuss immunity after natural infection and immunization. In addition, we highlight the main characteristics of the different technologies that have been applied for the development of a vaccine with broad protection against Shigella.

The value of public-private collaborative real-world evidence platforms to monitor vaccine performance post authorization: DRIVE - a European initiative

INTRODUCTION

Fighting pandemics requires an established infrastructure for pandemic preparedness, with existing, sustainable platforms ready to be activated. This includes platforms for disease surveillance, virus circulation, and vaccine performance monitoring based on Real-World data, to complement clinical trial evidence.

AREAS COVERED

Because of its complexity, this can best be done by combining efforts between public and private sectors, developing a multi-stakeholder approach. Public-Private-Partnerships increasingly play a critical role in combating infectious diseases but are still looked at with hesitancy. The Development of Robust and Innovative Vaccine Effectiveness (DRIVE) project, which established a platform for measuring brand-specific influenza vaccine effectiveness in Europe, exemplifies how to build a collaborative platform with transparent governance, state-of-the-art methodology, and a large network of participating sites. Lessons learned from DRIVE have been cardinal to set up COVIDRIVE, a platform for brand-specific COVID-19 vaccine effectiveness monitoring.

EXPERT OPINION

The DRIVE partners propose that a debate on the benefits of Public-Private-Partnership-generated real-world evidence for vaccine effectiveness monitoring should be pursued to clarify roles and responsibilities, set up expectations, and decide the future environment for vaccine monitoring in Europe. In parallel, the driving factors behind PPP hesitancy should be studied.

Younger Children Develop Higher Effector Antibody Responses to SARS-CoV-2 Infection

Background

The basis of the less severe clinical presentation of coronavirus disease 2019 (COVID-19) in children as compared with adults remains incompletely understood. Studies have suggested that a more potent boosting of immunity to endemic common cold coronaviruses (HCoVs) may protect children.

Methods

To test this hypothesis, we conducted a detailed analysis of antibodies induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in children aged 2 months to 14 years.

Results

Younger children had higher titers of antibodies to SARS-CoV-2 receptor binding domain (RBD), S1 but not S2 domain, and total spike (S) protein, higher avidity RBD immunoglobulin G, and higher titers of neutralizing and complement-activating antibodies as compared with older children. In contrast, older children had higher titers of antibodies to HCoVs, which correlated with antibodies to the SARS-CoV-2 S2 domain but not with neutralizing or complement-activating antibodies.

Conclusions

These results reveal a unique capacity of young children to develop effector antibody responses to SARS-CoV-2 infection independently of their immunity to HCoVs.

Immunization of preterm infants: current evidence and future strategies to individualized approaches

Preterm infants are at particularly high risk for infectious diseases. As this vulnerability extends beyond the neonatal period into childhood and adolescence, preterm infants benefit greatly from infection-preventive measures such as immunizations. However, there is an ongoing discussion about vaccine safety and efficacy due to preterm infants' distinct immunological features. A significant proportion of infants remains un- or under-immunized when discharged from primary hospital stay. Educating health care professionals and parents, promoting maternal immunization and evaluating the potential of new vaccination tools are important means to reduce the overall burden from infectious diseases in preterm infants. In this narrative review, we summarize the current knowledge about vaccinations in premature infants. We discuss the specificities of early life immunity and memory function, including the role of polyreactive B cells, restricted B cell receptor diversity and heterologous immunity mediated by a cross-reactive T cell repertoire. Recently, mechanistic studies indicated that tissue-resident memory (Trm) cell populations including T cells, B cells and macrophages are already established in the fetus. Their role in human early life immunity, however, is not yet understood. Tissue-resident memory T cells, for example, are diminished in airway tissues in neonates as compared to older children or adults. Hence, the ability to make specific recall responses after secondary infectious stimulus is hampered, a phenomenon that is transcriptionally regulated by enhanced expression of T-bet. Furthermore, the microbiome establishment is a dominant factor to shape resident immunity at mucosal surfaces, but it is often disturbed in the context of preterm birth. The proposed function of Trm T cells to remember benign interactions with the microbiome might therefore be reduced which would contribute to an increased risk for sustained inflammation. An improved understanding of Trm interactions may determine novel targets of vaccination, e.g., modulation of T-bet responses and facilitate more individualized approaches to protect preterm babies in the future.

Holistic Characterization of a Salmonella Typhimurium Infection Model Using Integrated Molecular Imaging

A more complete and holistic view on host-microbe interactions is needed to understand the physiological and cellular barriers that affect the efficacy of drug treatments and allow the discovery and development of new therapeutics. Here, we developed a multimodal imaging approach combining histopathology with mass spectrometry imaging (MSI) and same section imaging mass cytometry (IMC) to study the effects of Salmonella Typhimurium infection in the liver of a mouse model using the S. Typhimurium strains SL3261 and SL1344. This approach enables correlation of tissue morphology and specific cell phenotypes with molecular images of tissue metabolism. IMC revealed a marked increase in immune cell markers and localization in immune aggregates in infected tissues. A correlative computational method (network analysis) was deployed to find metabolic features associated with infection and revealed metabolic clusters of acetyl carnitines, as well as phosphatidylcholine and phosphatidylethanolamine plasmalogen species, which could be associated with pro-inflammatory immune cell types. By developing an IMC marker for the detection of Salmonella LPS, we were further able to identify and characterize those cell types which contained S. Typhimurium.

Vaccination as a Strategy to Prevent Bluetongue Virus Vertical Transmission

Bluetongue virus (BTV) produces an economically important disease in ruminants of compulsory notification to the OIE. BTV is typically transmitted by the bite of Culicoides spp., however, some BTV strains can be transmitted vertically, and this is associated with fetus malformations and abortions. The viral factors associated with the virus potency to cross the placental barrier are not well defined. The potency of vertical transmission is retained and sometimes even increased in live attenuated BTV vaccine strains. Because BTV possesses a segmented genome, the possibility of reassortment of vaccination strains with wild-type virus could even favor the transmission of this phenotype. In the present review, we will describe the non-vector-based BTV infection routes and discuss the experimental vaccination strategies that offer advantages over this drawback of some live attenuated BTV vaccines.

Long-Term Anti-Bacterial Immunity against Systemic Infection by Salmonella enterica Serovar Typhimurium Elicited by a GMMA-Based Vaccine

Salmonella Typhimurium (STm) represents the most prevalent cause of invasive non-typhoidal Salmonella (iNTS) disease, and currently no licensed vaccine is available. In this work we characterized the long-term anti-bacterial immunity elicited by a STm vaccine based on Generalized Modules of Membrane Antigens (GMMA) delivering O:4,5 antigen, using a murine model of systemic infection. Subcutaneous immunization of mice with STmGMMA/Alhydrogel elicited rapid, high, and persistent antigen-specific serum IgG and IgM responses. The serum was bactericidal in vitro. O:4,5-specific IgG were also detected in fecal samples after immunization and positively correlated with IgG observed in intestinal washes. Long-lived plasma cells and O:4,5-specific memory B cells were detected in spleen and bone marrow. After systemic STm challenge, a significant reduction of bacterial load in blood, spleen, and liver, as well as a reduction of circulating neutrophils and G-CSF glycoprotein was observed in STmGMMA/Alhydrogel immunized mice compared to untreated animals. Taken together, these data support the development of a GMMA-based vaccine for prevention of iNTS disease.

COVID-19 and vaccines in Africa: a descriptive and thematic analysis of Twitter content

Introduction: As coronavirus disease 2019 (COVID-19) vaccines become available, it becomes important to understand public perceptions of the vaccines and implementation plans. The social media platform TwitterTM, which publicly shares information, serves as an important source of content related to COVID-19 vaccines. This study employed a qualitative descriptive design to examine content related to COVID-19 vaccines posted by Twitter users located in Africa. Methods: Data were collected from Twitter between the 11th and the 16th of December 2020 using the NCapture tool. We searched Twitter using the terms 'coronavirus', 'COVID-19 vaccine' and 'Africa' to identify the nature and content of tweets related to COVID-19 and vaccines shared by Twitter users from the African region. Descriptive statistics were used to describe the characteristics of Twitter accounts and thematic analysis helped determine, analyse, and clarify patterns of meaning (themes) emerging from the tweets. Results: The study found n=208 Twitter accounts, the majority (n=69; 33%) from South Africa and most (42%; n=87) from news agencies. The final dataset included n=212 tweets. The most used hashtag was #Covid19vaccine(s). Four themes were identified: i) capacity for vaccine production, ii) vaccine procurement, iii) vaccine logistics, and iv) perceived safety and efficacy of vaccines. The capacity of countries in Africa to manufacture a COVID-19 vaccine was deemed minimal and most tweets questioned Africa’s ability to procure vaccines based on the costs. Tweets also centred around the distribution of vaccines, storage and roll-out and the need to leverage existing solar-powered technologies to enhance the cold supply chain in Africa's remote locations. Questions about the safety and efficacy of vaccines developed in under one year were also raised. Conclusions: Concerns about vaccine procurement and readiness for distribution were dominant topics. These public concerns can be important in informing policymakers in preparation for the roll-out of vaccines in these contexts.

Immunogenicity, safety and reactogenicity of ROTAVAC® in healthy infants aged 6-8 weeks in Vietnam

BACKGROUND

ROTAVAC® is derived from human 116E rotavirus (RV) neonatal strain. In this study, we evaluated the immunogenicity, safety and reactogenicity of ROTAVAC® in Vietnam.

METHOD

We conducted a phase IV clinical trial in healthy infants aged 6-8 weeks using the complete regimen of ROTAVAC® with three doses. Serum anti-RV IgA was measured by enzyme-linked immunosorbent assay to assess the geometric mean concentration in infants who received the complete regimen of the vaccine.

RESULTS

A total of 360 participants were enrolled in this clinical trial. The mean age ± standard deviation at enrollment was 6.9 ± 0.6 weeks. The anti-RV IgA titer was 4.01 ± 3.74 mg/ml pre-vaccination and substantially increased to 29.27 ± 80.64 mg/ml post-vaccination. The value of logIgA significantly increased (p = 0.003) from 0.28 ± 0.79 to 1.03 ± 0.54. The proportion of participants with equal to and greater than 3-fold and 4-fold shifts in pre- to post-vaccination antibody titer (IgA) were 55.4% and 48.3%, respectively. No adverse events or serious adverse events were recorded immediately within 30 min after the administration of each dose. The most common adverse events within 14 days after each visit were fever, unusual crying and irritability. Other adverse events occurred at a low rate, and no case of intussusception was noted.

CONCLUSIONS

The complete regimen of ROTAVAC® demonstrated an immunological response with clinically acceptable safety profile. Post-completion of this study, ROTAVAC® is now a WHO-prequalified vaccine and available in Vietnam.

Outer membrane vesicle vaccines

Outer Membrane Vesicles (OMV) have received increased attention in recent years as a vaccine platform against bacterial pathogens. OMV from Neisseria meningitidis serogroup B have been extensively explored. Following the success of the MeNZB OMV vaccine in controlling an outbreak of N. meningitidis B in New Zealand, additional research and development resulted in the licensure of the OMV-containing four-component 4CMenB vaccine, Bexsero. This provided broader protection against multiple meningococcal B strains. Advances in the field of genetic engineering have permitted further improvements in the platform resulting in increased yields, reduced endotoxicity and decoration with homologous and heterologous antigens to enhance immuno genicity and provide broader protection. The OMV vaccine platform has been extended to many other pathogens. In this review, we discuss progress in the development of the OMV vaccine delivery platform, highlighting successful applications, together with potential challenges and gaps.

Within-host spatiotemporal dynamic of systemic salmonellosis: Ways to track infection, reaction to vaccination and antimicrobial treatment

During the last two decades our understanding of the complex in vivo host-pathogen interactions has increased due to technical improvements and new research tools. The rapid advancement of molecular biology, flow cytometry and microscopy techniques, combined with mathematical modelling, have empowered in-depth studies of systemic bacterial infections across scales from single molecules, to cells, to organs and systems to reach the whole organism level. By tracking subpopulations of bacteria in vivo using molecular or fluorescent tags, it has been possible to reconstruct the spread of infection within and between organs, allowing unprecedented quantification of the effects of antimicrobial treatment and vaccination. This review illustrates recent advances in the study of heterogeneous traits of the infection process and illustrate approaches to investigate the reciprocal interactions between antimicrobial treatments, bacterial growth/death as well as inter- and intra-organ spread. We also discuss how vaccines impact the in vivo behaviour of bacteria and how these findings can guide vaccine design and rational antimicrobial treatment.

Vaccination strategies to enhance immunity in neonates

Neonates are particularly susceptible to infection. This vulnerability occurs despite their responsiveness to most vaccines. However, current vaccines do not target the pathogens responsible for most of the severe neonatal infections, and the time it takes to induce protective pathogen-specific immunity after vaccination limits protection in the first days to weeks of life. Alternative strategies include using vaccines to broadly stimulate neonatal immunity in a pathogen-agnostic fashion or vaccinating women during pregnancy to induce protective antibodies that are vertically transferred to offspring within their window of vulnerability. Protection may be further improved by integrating these approaches, namely vaccinating the neonate under the cover of vertically transferred maternal immunity. The rationale for and knowledge gaps related to each of these alternatives are discussed.

Identification of lipid A deacylase as a novel, highly conserved and protective antigen against enterohemorrhagic Escherichia coli

Enterohemorrhagic E. coli (EHEC) is a major cause of large outbreaks worldwide associated with hemorrhagic colitis and hemolytic uremic syndrome. While vaccine development is warranted, a licensed vaccine, specific for human use, against EHEC is not yet available. In this study, the reverse vaccinology approach combined with genomic, transcriptional and molecular epidemiology data was applied on the EHEC O157:H7 genome to select new potential vaccine candidates. Twenty-four potential protein antigens were identified and one of them (MC001) was successfully expressed onto Generalized Modules for Membrane Antigens (GMMA) delivery system. GMMA expressing this vaccine candidate was immunogenic, raising a specific antibody response. Immunization with the MC001 candidate was able to reduce the bacterial load of EHEC O157:H7 strain in feces, colon and caecum tissues after murine infection. MC001 is homologue to lipid A deacylase enzyme (LpxR), and to our knowledge, this is the first study describing it as a potential vaccine candidate. Gene distribution and sequence variability analysis showed that MC001 is present and conserved in EHEC and in enteropathogenic E. coli (EPEC) strains. Given the high genetic variability among and within E. coli pathotypes, the identification of such conserved antigen suggests that its inclusion in a vaccine might represent a solution against major intestinal pathogenic strains.

Preformulation Characterization and Stability Assessments of Secretory IgA Monoclonal Antibodies as Potential Candidates for Passive Immunization by Oral Administration

Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrheal disease among children in developing countries, and there are no licensed vaccines to protect against ETEC. Passive immunization by oral delivery of ETEC-specific secretory IgAs (sIgAs) could potentially provide an alternative approach for protection in targeted populations. In this study, a series of physiochemical techniques and an in vitro gastric digestion model were used to characterize and compare key structural attributes and stability profiles of 3 anti-heat-labile enterotoxin mAbs (sIgA1, sIgA2, and IgG1 produced in CHO cells). The mAbs were evaluated in terms of primary structure, N-linked glycan profiles, size and aggregate content, relative apparent solubility, conformational stability, and in vitro antigen binding. Compared to IgG1 mAb, sIgA1 and sIgA2 mAbs showed increased sample heterogeneity, especially in terms of N-glycan composition and the presence of higher molecular weight species. The sIgA mAbs showed overall better physical stability and were more resistant to loss of antigen binding activity during incubation at low pH, 37°C with pepsin. These results are discussed in terms of future challenges to design stable, low-cost formulations of sIgA mAbs as an oral supplement for passive immunization to protect against enteric diseases in the developing world.

A randomized, open-labelled, non-inferiority phase 4 clinical trial to evaluate the immunogenicity and safety of the live, attenuated, oral rotavirus vaccine, ROTAVAC® in comparison with a licensed rotavirus vaccine in healthy infants

BACKGROUND

ROTAVAC® (nHRV), derived naturally from the human 116E rotavirus (RV) neonatal strain, was licensed in India in 2015 based on promising results of a phase 3, safety and efficacy vaccine trial. As a pre-requisite for WHO prequalification, we compared the immunogenicity and safety of ROTAVAC® to those of a WHO-prequalified, Rotarix®.

METHODS

We conducted a multicentre, open-labeled, randomized phase 4 clinical trial where 464 infants, 6-8 weeks of age were equally randomized to receive as licensed, the complete regimen of ROTAVAC® (3 doses; Group I) or Rotarix® (2 doses; Group II). Antibody responses (serum anti-RV Immunoglobulin A [IgA]) were measured by enzyme-linked immunosorbent assay (ELISA). The primary analysis was an assessment of non-inferiority of ROTAVAC® to Rotarix® for geometric mean concentration (GMC) for infants who received the complete regimen of either vaccine.

RESULTS

The GMC for Group I was 20.4 (95%CI: 17.6, 23.6) and that for Group II was 24.8 (95%CI: 20.3, 30.3), the GMC ratio was 0.82 (95% CI: 0.64, 1.05), thus meeting the non-inferiority criterion. Site-wise analysis of GMC titres revealed that one site had a peculiar pre-vaccination titre affecting only ROTAVAC® post-vaccination GMCs. Seroconversion rates were 35.3% (95%CI: 29.0, 41.9) and 31.0% (95%CI: 25.1, 37.4) for Groups I and Group II, respectively. There was no substantive difference in safety profiles between both vaccines.

CONCLUSIONS

The complete regimen of ROTAVAC® demonstrated immunological non-inferiority to the complete regimen of Rotarix® with a clinically acceptable safety profile. Because the demand for RV vaccines is increasing as more countries are expanding their immunization schedules, the lack of need of a buffering agent, low dose volume (0.5 mL), non-interference with other concomitantly administered vaccines, and conformance with WHO-prequalification requirements provide ROTAVAC® the potential for widespread global usage. Post completion of this study, ROTAVAC® is now a WHO-prequalified vaccine.

CLINICAL TRIALS REGISTRATION

(CTRI Number: CTRI/2015/12/006428).

Vaccine Production in Africa: A Feasible Business Model for Capacity Building and Sustainable New Vaccine Introduction

Africa has the highest incidence of mortality caused by infectious diseases, and remarkably does not have the capacity to manufacture vaccines that are essential to reduce mortality, improving life expectancy, and promoting economic growth. GAVI has significantly helped introduction of new vaccines in Africa but its sustainability is questionable, and new vaccines introduction post-graduation is rare. Conversely, Africa with its high population and economy growth is an increasing potential market for vaccines. This study aimed to investigate how investment for vaccine production in Africa could be triggered and in which way it could be affordable to most African governments or investors. The investigation was based on a literature review and supplemented by online questionnaires directed to global vaccine stakeholders, African governments and regulatory authorities. In-depth interviews with experts in manufacturing capacity implementation and regulatory capacity building in Africa complemented the study. We also developed business plan scenarios including facility costs calculations and a possible investment plan based on expert opinions and publicly available information from pertinent sources. We saw that, governments in Africa, show interest in vaccine production establishments but only with external support for investment. The common regulatory functionality gap was the quality control laboratories to test vaccine lots before regulatory release. The global vaccine stakeholders showed less preference in investment for vaccine production establishment in Africa. The diverse political ambitions among African governments make it difficult to predict and access the market, a prerequisite for competitive production. A feasible solution could be a small production facility that would use technologies with high yield at low costs of goods to cover the regional needs. A respective antigen production facility is estimated to cost USD 25 Million, an affordable dimension for investors or interested African governments. Attractiveness for the African market is deemed to be high when targeting diseases almost exclusively for Africa (e.g., malaria or invasive non-typhoidal salmonella). With a smart 5 years tangible implementation plan, marketing agreements within existing regional collaborations and with a strong political will, an African government alone or together with an investor could convince global vaccine stakeholders and investors to support.

Knowledge and Perceptions of Adverse Events Following Immunization among Healthcare Professionals in Africa: A Case Study from Ghana

The spontaneous reporting of suspected adverse events following immunization (AEFI) by healthcare professionals (HCPs) is vital in monitoring post-licensure vaccine safety. The main objective of this study was to assess the knowledge and perceptions of AEFIs among healthcare professionals (HCPs) in Africa, using the situation in Ghana as a case study. The study was of a cross-sectional quantitative design, and was carried out from 1 July 2017 to 31 December 2017 with doctors, pharmacists, and nurses as the study participants. A 28-item paper-based questionnaire, delivered by hand to study participants, was the data collection tool in the study. The study was conducted in 4 hospitals after ethical approval was granted. The desired sample size was 686; however, 453 consented to partake in the study. Data were analyzed using SPSS (software version 22, IBM, Armonk, NY, USA), and chi-square and binary logistic regression tests were used for tests of association between HCPs’ characteristics and their knowledge and perceptions. Detailed knowledge of AEFIs was ascertained with a set of 9 questions, with 8 or 9 correctly answered questions signifying high knowledge, 5 to 7 correctly answered questions signifying moderate knowledge, and below 5 correctly answered questions signifying low knowledge. A set of 10 questions also ascertained HCPs’ positive and negative perceptions of AEFI. Results revealed that knowledge of AEFIs was high in 49 (10.8%) participants, moderate in 213 (47.0%) participants, and low in 191 (42.2%) participants. There was no statistically significant correlation between AEFI knowledge and professions. The highest negative perception was the lack of desire to learn more about how to diagnose, report, investigate, and manage AEFI, whereas the lowest was the lack of belief that surveillance improves public trust in immunization programs. There was a general awareness of AEFIs among HCPs in this study. However, negative perceptions and the lack of highly knowledgeable HCPs regarding AEFIs were possible setbacks to AEFI diagnosis, management, prevention, and reporting. More training and sensitization of HCPs on AEFIs and vaccine safety will be beneficial in improving the situation. Future research should focus on assessing the training materials and methodology used in informing HCPs about AEFIs and vaccine safety.

The Effect of Aromatherapy by Lavender Oil on Infant Vaccination Pain: a Double Blind Randomized Controlled Trial

Introduction: Exposure to noxious stimuli can cause pain in infants. This study was conducted to evaluate the effects of the lavender oil inhalation on the pain resulting from the pentavalent vaccination. Methods: This clinical trial consisted of two groups: the lavender oil group with 42 infants and the placebo group with 57 infants. The healthy infants without congenital abnormalities in need of pentavalent vaccine also participated in our study. The infants started the lavender oil or placebo aromatherapy one minute before injection. The pain was assessed three times, using the Neonatal Infant pain Scale (NIPS): before vaccination, 15 s, and 5 min after vaccination. Also, the duration of crying was measured in both groups. Results: At baseline, the two groups were similar in relation to the NIPS scores. While, after 5 minutes, the NIPS score was significantly lower in the lavender group. Based on the repeated measures analysis, the NIPS score changed over time totally. However, the two groups were significantly different in relation to the NIPS score over time. The duration of crying was 75.47 (60.675) second in the lavender group and 105.22 (75.739) s in the control group. The statistical test showed a significant difference between the two groups. Conclusion: A low concentration of the lavender oil inhalation can reduce the pain and improve soothing in the infants with the pentavalent vaccine injection.

The essential role of complement in antibody-mediated resistance to Salmonella

Vaccines can serve as essential tools to prevent bacterial diseases via the induction of long-lasting IgG responses. The efficacy of such vaccines depends on the effector mechanisms triggered by IgG. The complement system and Fc-gamma receptors (FcγRs) can potentially play a crucial role in IgG-mediated immunity against bacterial diseases. However, their relative importance in vivo is unclear, and has been the object of controversy and debate. In this brief study, we have used gene-targeted mice lacking either FcγRI, II, II and IV or the C3 complement component as well as a novel mouse strain lacking both C3 and FcγRs to conclusively show the essential role of complement in antibody-mediated host resistance to Salmonella enterica systemic infection. By comparing the effect of IgG2a antibodies against Salmonella O-antigen in gene-targeted mice, we demonstrate that the complement system is essential for the IgG-mediated reduction of bacterial numbers in the tissues.

Comparative immunogenicity and efficacy of equivalent outer membrane vesicle and glycoconjugate vaccines against nontyphoidal Salmonella

Nontyphoidal Salmonellae cause a devastating burden of invasive disease in sub-Saharan Africa with high levels of antimicrobial resistance. Vaccination has potential for a major global health impact, but no licensed vaccine is available. The lack of commercial incentive makes simple, affordable technologies the preferred route for vaccine development. Here we compare equivalent Generalized Modules for Membrane Antigens (GMMA) outer membrane vesicles and O-antigen-CRM₁₉₇ glycoconjugates to deliver lipopolysaccharide O-antigen in bivalent Salmonella Typhimurium and Enteritidis vaccines. Salmonella strains were chosen and tolR deleted to induce GMMA production. O-antigens were extracted from wild-type bacteria and conjugated to CRM₁₉₇ Purified GMMA and glycoconjugates were characterized and tested in mice for immunogenicity and ability to reduce Salmonella infection. GMMA and glycoconjugate O-antigen had similar structural characteristics, O-acetylation, and glucosylation levels. Immunization with GMMA induced higher anti-O-antigen IgG than glycoconjugate administered without Alhydrogel adjuvant. With Alhydrogel, antibody levels were similar. GMMA induced a diverse antibody isotype profile with greater serum bactericidal activity than glycoconjugate, which induced almost exclusively IgG1. Immunization reduced bacterial colonization of mice subsequently infected with SalmonellaS Typhimurium numbers were lower in tissues of mice vaccinated with GMMA compared with glycoconjugate. S. Enteritidis burden in the tissues was similar in mice immunized with either vaccine. With favorable immunogenicity, low cost, and ability to induce functional antibodies and reduce bacterial burden, GMMA offer a promising strategy for the development of a nontyphoidal Salmonella vaccine compared with established glycoconjugates. GMMA technology is potentially attractive for development of vaccines against other bacteria of global health significance.

Fusion to Tetrahymena thermophila granule lattice protein 1 confers solubility to sexual stage malaria antigens in Escherichia coli

A transmission-blocking vaccine targeting the sexual stages of Plasmodium species could play a key role in eradicating malaria. Multiple studies have identified the P. falciparum proteins Pfs25 and Pfs48/45 as prime targets for transmission-blocking vaccines. Although significant advances have been made in recombinant expression of these antigens, they remain difficult to produce at large scale and lack strong immunogenicity as subunit antigens. We linked a self-assembling protein, granule lattice protein 1 (Grl1p), from the ciliated protozoan, Tetrahymena thermophila, to regions of the ectodomains of either Pfs25 or Pfs48/45. We found that resulting protein chimera could be produced in E. coli as nanoparticles that could be readily purified in soluble form. When produced in the E. coli SHuffle strain, fusion to Grl1p dramatically increased solubility of target antigens while at the same time directing the formation of particles with diameters centering on 38 and 25 nm depending on the antigen. In a number of instances, co-expression with chaperone proteins and induction at a lower temperature further increased expression and solubility. Based on Western blotting and ELISA analysis, Pfs25 and Pfs48/45 retained their transmission-blocking epitopes within E. coli-derived particles, and the particles themselves elicited strong antibody responses in rabbits when given with an aluminum-based adjuvant. Antibodies against Pfs25-containing nanoparticles blocked parasite transmission in standard membrane-feeding assays. In conclusion, fusion to Grl1p can act as a solubility enhancer for proteins with limited solubility while retaining correct folding, which may be useful for applications such as the production of vaccines and other biologics.

Within-host spatiotemporal dynamics of systemic Salmonella infection during and after antimicrobial treatment

Objectives

We determined the interactions between efficacy of antibiotic treatment, pathogen growth rates and between-organ spread during systemic Salmonella infections.

Methods

We infected mice with isogenic molecularly tagged subpopulations of either a fast-growing WT or a slow-growing ΔaroC Salmonella strain. We monitored viable bacterial numbers and fluctuations in the proportions of each bacterial subpopulation in spleen, liver, blood and mesenteric lymph nodes (MLNs) before, during and after the cessation of treatment with ampicillin and ciprofloxacin.

Results

Both antimicrobials induced a reduction in viable bacterial numbers in the spleen, liver and blood. This reduction was biphasic in infections with fast-growing bacteria, with a rapid initial reduction followed by a phase of lower effect. Conversely, a slow and gradual reduction of the bacterial load was seen in infections with the slow-growing strain, indicating a positive correlation between bacterial net growth rates and the efficacy of ampicillin and ciprofloxacin. The viable numbers of either bacterial strain remained constant in MLNs throughout the treatment with a relapse of the infection with WT bacteria occurring after cessation of the treatment. The frequency of each tagged bacterial subpopulation was similar in the spleen and liver, but different from that of the MLNs before, during and after treatment.

Conclusions

In Salmonella infections, bacterial growth rates correlate with treatment efficacy. MLNs are a site with a bacterial population structure different to those of the spleen and liver and where the total viable bacterial load remains largely unaffected by antimicrobials, but can resume growth after cessation of treatment.

Using preceding hospital admissions to identify children at risk of developing acute rheumatic fever

AIMS

New Zealand (NZ) Māori and Pacific children have high rates of acute rheumatic fever (ARF). Around 150 new cases arise each year. As part of the national ARF prevention programme, funding is available to improve housing. To obtain maximum benefit from interventions, an effective tool is needed for targeting high-risk children. This study aimed to assess the effectiveness of using hospitalisations for identifying children at risk of subsequent ARF.

METHODS

Three potentially avoidable hospitalisation (PAH) groups were investigated, including diseases thought to be influenced by housing. All were developed using expert opinion or systematic reviews. These were: (i) the PAH conditions associated with the housing environment (PAHHE) group; (ii) the Crowding group; and (iii) the Ministry of Health (MoH) group. We analysed NZ public hospital discharge data (2000-2014). The prevalence of ARF among patients hospitalised in each group was calculated to estimate sensitivity and potential effectiveness. The number needed to screen (NNS) to identify one ARF case was estimated as a measure of efficiency.

RESULTS

Nearly one-third of ARF patients experienced a PAH as children (before developing ARF). Sensitivity for detecting future ARF ranged from <5% (MoH group) to 27% (PAHHE group). NNS ranged from 502.4 (PAHHE) to 707.5 (MoH).

CONCLUSIONS

Because ARF is relatively rare, observing hospitalisations is not particularly efficient for targeting prevention activities for this condition alone. However, housing interventions are likely to improve multiple outcomes; thus, the hospital setting is still useful for identifying at-risk children who could benefit from such programmes.

Poverty reduction and equity benefits of introducing or scaling up measles, rotavirus and pneumococcal vaccines in low-income and middle-income countries: a modelling study

Introduction

Beyond their impact on health, vaccines can lead to large economic benefits. While most economic evaluations of vaccines have focused on the health impact of vaccines at a national scale, it is critical to understand how their impact is distributed along population subgroups.

Methods

We build a financial risk protection model to evaluate the impact of immunisation against measles, severe pneumococcal disease and severe rotavirus for birth cohorts vaccinated over 2016-2030 for three scenarios in 41 Gavi-eligible countries: no immunisation, current immunisation coverage forecasts and the current immunisation coverage enhanced with funding support. We distribute modelled disease cases per socioeconomic group and derive the number of cases of: (1) catastrophic health costs (CHCs) and (2) medical impoverishment.

Results

In the absence of any vaccine coverage, the number of CHC cases attributable to measles, severe pneumococcal disease and severe rotavirus would be approximately 18.9 million, 6.6 million and 2.2 million, respectively. Expanding vaccine coverage would reduce this number by up to 90%, 30% and 40% in each case. More importantly, we find a higher share of CHC incidence among the poorest quintiles who consequently benefit more from vaccine expansion.

Conclusion

Our findings contribute to the understanding of how vaccines can have a broad economic impact. In particular, we find that immunisation programmes can reduce the proportion of households facing catastrophic payments from out-of-pocket health expenses, mainly in lower socioeconomic groups. Thus, vaccines could have an important role in poverty reduction.

Intestinal Pathogenic Escherichia coli: Insights for Vaccine Development

Diarrheal diseases are one of the major causes of mortality among children under five years old and intestinal pathogenic Escherichia coli (InPEC) plays a role as one of the large causative groups of these infections worldwide. InPECs contribute significantly to the burden of intestinal diseases, which are a critical issue in low- and middle-income countries (Asia, Africa and Latin America). Intestinal pathotypes such as enteropathogenic E. coli (EPEC) and enterotoxigenic E. coli (ETEC) are mainly endemic in developing countries, while ETEC strains are the major cause of diarrhea in travelers to these countries. On the other hand, enterohemorrhagic E. coli (EHEC) are the cause of large outbreaks around the world, mainly affecting developed countries and responsible for not only diarrheal disease but also severe clinical complications like hemorrhagic colitis and hemolytic uremic syndrome (HUS). Overall, the emergence of antibiotic resistant strains, the annual cost increase in the health care system, the high incidence of traveler diarrhea and the increased number of HUS episodes have raised the need for effective preventive treatments. Although the use of antibiotics is still important in treating such infections, non-antibiotic strategies are either a crucial option to limit the increase in antibiotic resistant strains or absolutely necessary for diseases such as those caused by EHEC infections, for which antibiotic therapies are not recommended. Among non-antibiotic therapies, vaccine development is a strategy of choice but, to date, there is no effective licensed vaccine against InPEC infections. For several years, there has been a sustained effort to identify efficacious vaccine candidates able to reduce the burden of diarrheal disease. The aim of this review is to summarize recent milestones and insights in vaccine development against InPECs.

Genetic fusion protein 3×STa-ovalbumin is an effective coating antigen in ELISA to titrate anti-STa antibodies

Heat-stable toxin type I (STa)-ovalbumin chemical conjugates are currently used as the only coating antigen in ELISA to titrate anti-STa antibodies for ETEC vaccine candidates. STa-ovalbumin chemical conjugation requires STa toxin purification, a process that can be carried out by only a couple of laboratories and often with a low yield. Alternative ELISA coating antigens are needed for anti-STa antibody titration for ETEC vaccine development. In the present study, we genetically fused STa toxin gene (three copies) to a modified chicken ovalbumin gene for genetic fusion 3×STa-ovalbumin, and examined application of this fusion protein as an alternative coating antigen of anti-STa antibody titration ELISA. Data showed fusion protein 3×STa-ovalbumin was effectively expressed and extracted, and anti-STa antibody titration ELISA using this recombinant protein (25 ng per well) or STa-ovalbumin chemical conjugates (10 ng/well) showed the same levels of sensitivity and specificity. Furthermore, mice immunized with this fusion protein developed anti-STa antibodies; induced antibodies showed in vitro neutralization activity against STa toxin. These results indicate that recombinant fusion protein 3×STa-ovalbumin is an effective ELISA coating antigen for anti-STa antibody titration, enabling a reliable reagent supply to make standardization of STa antibody titration assay feasible and to accelerate ETEC vaccine development.

Efficacy of a Low-Cost, Heat-Stable Oral Rotavirus Vaccine in Niger

BACKGROUND

Each year, rotavirus gastroenteritis is responsible for about 37% of deaths from diarrhea among children younger than 5 years of age worldwide, with a disproportionate effect in sub-Saharan Africa.

METHODS

We conducted a randomized, placebo-controlled trial in Niger to evaluate the efficacy of a live, oral bovine rotavirus pentavalent vaccine (BRV-PV, Serum Institute of India) to prevent severe rotavirus gastroenteritis. Healthy infants received three doses of the vaccine or placebo at 6, 10, and 14 weeks of age. Episodes of gastroenteritis were assessed through active and passive surveillance and were graded on the basis of the score on the Vesikari scale (which ranges from 0 to 20, with higher scores indicating more severe disease). The primary end point was the efficacy of three doses of vaccine as compared with placebo against a first episode of laboratory-confirmed severe rotavirus gastroenteritis (Vesikari score, ≥11) beginning 28 days after dose 3.

RESULTS

Among the 3508 infants who were included in the per-protocol efficacy analysis, there were 31 cases of severe rotavirus gastroenteritis in the vaccine group and 87 cases in the placebo group (2.14 and 6.44 cases per 100 person-years, respectively), for a vaccine efficacy of 66.7% (95% confidence interval [CI], 49.9 to 77.9). Similar efficacy was seen in the intention-to-treat analyses, which showed a vaccine efficacy of 69.1% (95% CI, 55.0 to 78.7). There was no significant between-group difference in the risk of adverse events, which were reported in 68.7% of the infants in the vaccine group and in 67.2% of those in the placebo group, or in the risk of serious adverse events (in 8.3% in the vaccine group and in 9.1% in the placebo group); there were 27 deaths in the vaccine group and 22 in the placebo group. None of the infants had confirmed intussusception.

CONCLUSIONS

Three doses of BRV-PV, an oral rotavirus vaccine, had an efficacy of 66.7% against severe rotavirus gastroenteritis among infants in Niger. (Funded by Médecins sans Frontières Operational Center and the Kavli Foundation; ClinicalTrials.gov number, NCT02145000 .).

Prioritizing vaccines for developing world diseases

A major disparity in the burden of health will need to be addressed to achieve the "Grand Convergence" by 2035. In particular people living in low and middle income countries have a much higher burden of infectious diseases. Although vaccines have been very effective in reducing the global burden of infectious disease, there are no registered vaccines to address 60% of the current burden of infectious disease, especially in developing countries. Thus there is a pressing need for new vaccines and for prioritizing vaccine development given that resources for developing new vaccines are strictly limited. As part of the GLOBAL HEALTH 2035: Mission Grand Convergence meeting one working group assessed the SMART vaccine algorithm as a mechanism for prioritizing vaccine development for diseases of priority in the developing world. In particular, the working group considered which criteria in the standard SMART set were considered "key" criteria and whether other criteria should be considered, when prioritizing vaccines for this important set of countries.

An efficient cell free enzyme-based total synthesis of a meningococcal vaccine candidate

Invasive meningococcal disease (IMD) is a global health problem and vaccination has proven the most effective way of disease control. Neisseria meningitidis serogroup X (NmX) is an emerging threat in the African sub-Saharan meningitis belt, but no vaccine is available today. Leading vaccines against Nm are glycoconjugates, in which capsular polysaccharides isolated from large-scale pathogen cultures are conjugated to adjuvant proteins. Though safe and efficacious even in infants, high costs and biohazard associated with the production limit abundant application of glycoconjugate vaccines particularly in the most afflicted nations. An existing NmX vaccine candidate (CPSXn-CRM₁₉₇) produced by established protocols from NmX capsule polysaccharide (CPSX) has been shown to elicit high bactericidal immunoglobulin G titres in mice. Here we describe the scalable in vitro synthesis of CPSXiv from chemically pure precursors by the use of recombinant NmX capsule polymerase. Application of the described coupling chemistry gives CPSXiv-CRM₁₉₇, which in mouse vaccination experiments behaves identical to the benchmark CPSXn-CRM₁₉₇. Excluding any biohazards, this novel process represents a paradigm shift in vaccine production and a premise towards vaccine manufacturing in emerging economies.

Challenges and Opportunities While Developing a Group A Meningococcal Conjugate Vaccine Within a Product Development Partnership: A Manufacturer's Perspective From the Serum Institute of India

Background. In 2002, the Meningitis Vaccine Project (MVP) chose the Serum Institute of India, Ltd (SIIL), as its manufacturing partner to establish a product development partnership (PDP) with the Meningitis Vaccine Project (MVP). MVP was a collaboration between PATH and the World Health Organization (WHO) to develop meningococcal conjugate vaccines for sub-Saharan Africa.

Method. From the outset, SIIL recognized that a partnership with MVP carried some risk but also offered important opportunities for accessing new conjugate vaccine technology and know-how. Over 3 years, SIIL successfully accepted technology transfer for the group A meningococcal polysaccharide from SynCo Bio Partners and a conjugation method from the US Food and Drug Administration.

Results. SIIL successfully scaled up production of a group A meningococcal conjugate vaccine that used SIIL tetanus toxoid as the carrier protein. Phase 1 studies began in India in 2005, followed by phase 2/3 studies in Africa and India. A regulatory dossier was submitted to the Indian authorities in April 2009 and WHO in September 2009. Export license was granted in December 2009, and WHO prequalification was obtained in June 2010. Vaccine was introduced at public scale in Burkina Faso that December. The group A meningococcal conjugate vaccine was named MenAfriVac, and is the first internationally qualified vaccine developed outside of big pharma.

Conclusions. The project proved to be a sound investment for SIIL and is a concrete example of the potential for PDPs to provide needed products for resource-poor countries.

Status of vaccine research and development for norovirus

The global health community is beginning to gain an understanding of the global burden of norovirus-associated disease, which appears to have significant burden in both developed- and developing-country populations. Of particular importance is the growing recognition of norovirus as a leading cause of gastroenteritis and diarrhea in countries where rotavirus vaccine has been introduced. While not as severe as rotavirus disease, the sheer number of norovirus infections not limited to early childhood makes norovirus a formidable global health problem. This article provides a landscape review of norovirus vaccine development efforts. Multiple vaccine strategies, mostly relying on virus-like particle antigens, are under development and have demonstrated proof of efficacy in human challenge studies. Several are entering phase 2 clinical development. Norovirus vaccine development challenges include, but are not limited to: valency, induction of adequate immune responses in pediatric and elderly populations, and potential for vaccine-strain mismatch. Given current strategies and global health interest, the outlook for a norovirus vaccine is promising. Because a norovirus vaccine is expected to have a dual market in both developed and developing countries, there would likely be scale-up advantages for commercial development and global distribution. Combination with or expression by another enteric pathogen, such as rotavirus, could also enhance uptake of a norovirus vaccine.

Did Neoliberalizing West African Forests Produce a New Niche for Ebola?

A recent study introduced a vaccine that controls Ebola Makona, the Zaire ebolavirus variant that has infected 28,000 people in West Africa. We propose that even such successful advances are insufficient for many emergent diseases. We review work hypothesizing that Makona, phenotypically similar to much smaller outbreaks, emerged out of shifts in land use brought about by neoliberal economics. The epidemiological consequences demand a new science that explicitly addresses the foundational processes underlying multispecies health, including the deep-time histories, cultural infrastructure, and global economic geographies driving disease emergence. The approach, for instance, reverses the standard public health practice of segregating emergency responses and the structural context from which outbreaks originate. In Ebola's case, regional neoliberalism may affix the stochastic "friction" of ecological relationships imposed by the forest across populations, which, when above a threshold, keeps the virus from lining up transmission above replacement. Export-led logging, mining, and intensive agriculture may depress such functional noise, permitting novel spillovers larger forces of infection. Mature outbreaks, meanwhile, can continue to circulate even in the face of efficient vaccines. More research on these integral explanations is required, but the narrow albeit welcome success of the vaccine may be used to limit support of such a program.

Epidemiology, Clinical Presentation, Laboratory Diagnosis, Antimicrobial Resistance, and Antimicrobial Management of Invasive Salmonella Infections

Salmonella enterica infections are common causes of bloodstream infection in low-resource areas, where they may be difficult to distinguish from other febrile illnesses and may be associated with a high case fatality ratio. Microbiologic culture of blood or bone marrow remains the mainstay of laboratory diagnosis. Antimicrobial resistance has emerged in Salmonella enterica, initially to the traditional first-line drugs chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole. Decreased fluoroquinolone susceptibility and then fluoroquinolone resistance have developed in association with chromosomal mutations in the quinolone resistance-determining region of genes encoding DNA gyrase and topoisomerase IV and also by plasmid-mediated resistance mechanisms. Resistance to extended-spectrum cephalosporins has occurred more often in nontyphoidal than in typhoidal Salmonella strains. Azithromycin is effective for the management of uncomplicated typhoid fever and may serve as an alternative oral drug in areas where fluoroquinolone resistance is common. In 2013, CLSI lowered the ciprofloxacin susceptibility breakpoints to account for accumulating clinical, microbiologic, and pharmacokinetic-pharmacodynamic data suggesting that revision was needed for contemporary invasive Salmonella infections. Newly established CLSI guidelines for azithromycin and Salmonella enterica serovar Typhi were published in CLSI document M100 in 2015.

Current Progress in Developing Subunit Vaccines against Enterotoxigenic Escherichia coli-Associated Diarrhea

Diarrhea continues to be a leading cause of death in children <5 years of age, and enterotoxigenic Escherichia coli (ETEC) is the most common bacterial cause of children's diarrhea. Currently, there are no available vaccines against ETEC-associated diarrhea. Whole-cell vaccine candidates have been under development but require further improvements because they provide inadequate protection and produce unwanted adverse effects. Meanwhile, a newer approach using polypeptide or subunit vaccine candidates focusing on ETEC colonization factor antigens (CFAs) and enterotoxins, the major virulence determinants of ETEC diarrhea, shows substantial promise. A conservative CFA/I adhesin tip antigen and a CFA MEFA (multiepitope fusion antigen) were shown to induce cross-reactive antiadhesin antibodies that protected against adherence by multiple important CFAs. Genetic fusion of toxoids derived from ETEC heat-labile toxin (LT) and heat-stable toxin (STa) induced antibodies neutralizing both enterotoxins. Moreover, CFA-toxoid MEFA polypeptides, generated by fusing CFA MEFA to an STa-LT toxoid fusion, induced antiadhesin antibodies that broadly inhibited adherence of the seven most important ETEC CFAs associated with about 80% of the diarrhea cases caused by ETEC strains with known CFAs. This same antigen preparation also induced antitoxin antibodies that neutralized both toxins that are associated with all cases of ETEC diarrhea. Results from these studies suggest that polypeptide or subunit vaccines have the potential to effectively protect against ETEC diarrhea. In addition, novel adhesins and mucin proteases have been investigated as potential alternatives or, more likely, additional antigens for ETEC subunit vaccine development.

Delivering vaccines to the people who need them most

Thanks to the Global Alliance for Vaccines and Immunization (GAVI), the Vaccine Fund and the Bill & Melinda Gates Foundation, the global health community has made enormous progress in providing already existing vaccines to developing countries. However, there still exists a gap to develop vaccines for which there is no market in the Western world, owing to low economic incentives for the private sector to justify the investments necessary for vaccine development. In many cases, industry has the technologies, but lacks the impetus to direct resources to develop these vaccine products. The present emergency with the Ebola vaccine provides us an excellent example where a vaccine was feasible several years ago, but the global health community waited for a humanitarian disaster to direct efforts and resources to develop this vaccine. In the beginning of 2015, the first large-scale trials of two experimental vaccines against Ebola virus disease have begun in West Africa. During the past few years, several institutions have dedicated efforts to the development of vaccines against diseases present only in low-income countries. These include the International Vaccine Institute, the Novartis Vaccines Institute for Global Health, the Hilleman Institute, the Sabin Vaccine Institute and the Infectious Disease Research Institute. Nevertheless, solving this problem requires a more significant global effort than that currently invested. These efforts include a clear policy, global coordination of funds dedicated to the development of neglected disease and an agreement on regulatory strategies and incentives for the private sector.

Vaccines, new opportunities for a new society

Vaccination is the most effective medical intervention ever introduced and, together with clean water and sanitation, it has eliminated a large part of the infectious diseases that once killed millions of people. A recent study concluded that since 1924 in the United States alone, vaccines have prevented 40 million cases of diphtheria, 35 million cases of measles, and a total of 103 million cases of childhood diseases. A report from the World Health Organization states that today vaccines prevent 2.5 million deaths per year: Every minute five lives are saved by vaccines worldwide. Overall, vaccines have done and continue to do an excellent job in eliminating or reducing the impact of childhood diseases. Furthermore, thanks to new technologies, vaccines now have the potential to make an enormous contribution to the health of modern society by preventing and treating not only communicable diseases in all ages, but also noncommunicable diseases such as cancer and neurodegenerative disorders. The achievement of these results requires the development of novel technologies and health economic models able to capture not only the mere cost-benefit of vaccination, but also the value of health per se.