Background incidence rates of health outcomes in populations at risk for Lyme disease using US administrative claims data

BACKGROUND

Background incidence rates (IRs) of health outcomes in Lyme disease endemic regions are useful to contextualize events reported during Lyme disease vaccine clinical trials or post-marketing. The objective of this study was to estimate and compare IRs of health outcomes in Lyme disease endemic versus non-endemic regions in the US during pre-COVID and COVID era timeframes.

METHODS

IQVIA PharMetrics® Plus commercial claims database was used to estimate IRs of 64 outcomes relevant to vaccine safety monitoring in the US during January 1, 2017-December 31, 2019 and January 1, 2020-December 31, 2021. Analyses included all individuals aged ≥ 2 years with ≥ 1 year of continuous enrollment. Outcomes were defined by International Classification of Diseases Clinical Modification, 10th Revision (ICD-10-CM) diagnosis codes. IRs and 95 % confidence intervals (CIs) were calculated for each outcome and compared between endemic vs. non-endemic regions, and pre-COVID vs. COVID era using IR ratios (IRR).

RESULTS

The study population included 8.7 million (M) in endemic and 27.8 M in non-endemic regions. Mean age and sex were similar in endemic and non-endemic regions. In both study periods, the IRs were statistically higher in endemic regions for anaphylaxis, meningoencephalitis, myocarditis/pericarditis, and rash (including erythema migrans) as compared with non-endemic regions. Conversely, significantly lower IRs were observed in endemic regions for acute kidney injury, disseminated intravascular coagulation, heart failure, myelitis, myopathies, and systemic lupus erythematosus in both study periods. Most outcomes were statistically less frequent during the COVID-era.

CONCLUSION

This study identified potential differences between Lyme endemic and non-endemic regions of the US in background IRs of health conditions during pre-COVID and COVID era timeframes to inform Lyme disease vaccine safety monitoring. These regional and temporal differences in background IRs should be considered when contextualizing possible safety signals in clinical trials and post-marketing of a vaccine targeted at Lyme disease prevention.

Efficacy Evaluation of an Intradermally Delivered Enterotoxigenic Escherichia coli CF Antigen I Fimbrial Tip Adhesin Vaccine Coadministered with Heat-Labile Enterotoxin with LT(R192G) against Experimental Challenge with Enterotoxigenic E. coli H10407 in Healthy Adult Volunteers

BACKGROUND

Enterotoxigenic E. coli (ETEC) is a principal cause of diarrhea in travelers, deployed military personnel, and children living in low to middle-income countries. ETEC expresses a variety of virulence factors including colonization factors (CF) that facilitate adherence to the intestinal mucosa. We assessed the protective efficacy of a tip-localized subunit of CF antigen I (CFA/I), CfaE, delivered intradermally with the mutant E. coli heat-labile enterotoxin, LTR192G, in a controlled human infection model (CHIM).

METHODS

Three cohorts of healthy adult subjects were enrolled and given three doses of 25 μg CfaE + 100 ng LTR192G vaccine intradermally at 3-week intervals. Approximately 28 days after the last vaccination, vaccinated and unvaccinated subjects were admitted as inpatients and challenged with approximately 2 × 107 cfu of CFA/I+ ETEC strain H10407 following an overnight fast. Subjects were assessed for moderate-to-severe diarrhea for 5 days post-challenge.

RESULTS

A total of 52 volunteers received all three vaccinations; 41 vaccinated and 43 unvaccinated subjects were challenged and assessed for moderate-to-severe diarrhea. Naïve attack rates varied from 45.5% to 64.7% across the cohorts yielding an overall efficacy estimate of 27.8% (95% confidence intervals: -7.5-51.6%). In addition to reducing moderate-severe diarrhea rates, the vaccine significantly reduced loose stool output and overall ETEC disease severity.

CONCLUSIONS

This is the first study to demonstrate protection against ETEC challenge after intradermal vaccination with an ETEC adhesin. Further examination of the challenge methodology is necessary to address the variability in naïve attack rate observed among the three cohorts in the present study.

Gut microbiome and antibiotic resistance effects during travelers' diarrhea treatment and prevention

IMPORTANCE

The travelers' gut microbiome is potentially assaulted by acute and chronic perturbations (e.g., diarrhea, antibiotic use, and different environments). Prior studies of the impact of travel and travelers' diarrhea (TD) on the microbiome have not directly compared antibiotic regimens, and studies of different antibiotic regimens have not considered travelers' microbiomes. This gap is important to be addressed as the use of antibiotics to treat or prevent TD-even in moderate to severe cases or in regions with high infectious disease burden-is controversial based on the concerns for unintended consequences to the gut microbiome and antimicrobial resistance (AMR) emergence. Our study addresses this by evaluating the impact of defined antibiotic regimens (single-dose treatment or daily prophylaxis) on the gut microbiome and resistomes of deployed servicemembers, using samples collected during clinical trials. Our findings indicate that the antibiotic treatment regimens that were studied generally do not lead to adverse effects on the gut microbiome and resistome and identify the relative risks associated with prophylaxis. These results can be used to inform therapeutic guidelines for the prevention and treatment of TD and make progress toward using microbiome information in personalized medical care.

Reassessing potential economic value and health impact of effective Shigella vaccines

The gram-negative bacterium Shigella is a leading cause of diarrheal morbidity and mortality in children in low- and middle-income countries. Several promising vaccine candidates are in late stages of clinical development against this increasingly antibiotic-resistant pathogen. However, considering the increasingly crowded and costly paediatric immunization schedule, and likely advent of other important new vaccines, it is unclear whether introduction of a Shigella vaccine would represent a high priority for international agencies or health ministries in low- and middle-income countries. To determine whether there is a compelling public health value proposition for a Shigella vaccine, we used the World Health Organization's Full Value of Vaccine Assessment analytic framework and formulated five broad scientific, policy, economic and commercial-related propositions regarding the development of a Shigella vaccine. We also explored the current regulatory, clinical, policy and commercial challenges to a Shigella-containing combination vaccine development and adoption. Through a series of literature reviews, expert consultations, social science field studies and model-based analyses, we addressed each of these propositions. As described in a series of separate publications that are synthesized here, we concluded that the economic and public health value of a Shigella vaccine may be greater than previously recognized, particularly if it is found to also be effective against less severe forms of diarrheal disease and childhood stunting. The decision by pharmaceutical companies to develop a standalone vaccine or a multipathogen combination will be a key factor in determining its relative prioritization by various stakeholders in low- and middle-income countries.

Vaccine value profile for norovirus

Norovirus is attributed to nearly 1 out of every 5 episodes of diarrheal disease globally and is estimated to cause approximately 200,000 deaths annually worldwide, with 70,000 or more among children in developing countries. Noroviruses remain a leading cause of sporadic disease and outbreaks of acute gastroenteritis even in industrialized settings, highlighting that improved hygiene and sanitation alone may not be fully effective in controlling norovirus. Strengths in global progress towards a Norovirus vaccine include a diverse though not deep pipeline which includes multiple approaches, including some with proven technology platforms (e.g., VLP-based HPV vaccines). However, several gaps in knowledge persist, including a fulsome mechanistic understanding of how the virus attaches to human host cells, internalizes, and induces disease.

Serum antibody levels to SARS-CoV-2 receptor-binding domain (RBD) in convalescent patients and vaccinated individuals of northern Nevada

Antibodies reactive with the SARS-CoV-2 receptor-binding domain (RBD) of the spike protein are associated with viral neutralization, however low antibody titers, specifically against SARS-CoV-2 variants, may result in reduced viral immunity post naturally acquired infection. A cohort study comprised of 121 convalescent individuals from northern Nevada was conducted looking at anti-RBD antibody levels by enzyme-linked immunosorbent assay. Serum was collected from volunteers by staff at the University of Nevada, Reno School of Medicine Clinical Research Center and assessed for antibodies reactive to various SARS-CoV-2 RBD domains relevant to the time of the study (2020-2021). A nonpaired group of vaccinated individuals were assessed in parallel. The goal of the study was to identify antibody levels against the RBD subunit in convalescent and vaccinated individuals from northern Nevada.

A First in Human Clinical Trial Assessing the Safety and Immunogenicity of Two Intradermally Delivered Enterotoxigenic Escherichia coli CFA/I Fimbrial Tip Adhesin Antigens with and without Heat-Labile Enterotoxin with Mutation LT(R192G)

INTRODUCTION

Enterotoxigenic E. coli (ETEC) is a leading cause of diarrhea in travelers as well as for children living in low- to middle-income countries. ETEC adhere to intestinal epithelium via colonization factors (CFs). CFA/I, a common CF, is composed of a polymeric stalk and a tip-localized minor adhesive subunit, CfaE. Vaccine delivery by the transcutaneous immunization of dscCfaE was safe but was poorly immunogenic in a phase 1 trial when administered to volunteers with LTR(192G) and mLT. To potentially enhance the immunogenicity of CfaE while still delivering via a cutaneous route, we evaluated the safety and immunogenicity of two CfaE constructs administered intradermally (ID) with or without mLT.

METHODS

CfaE was evaluated as a donor strand-complemented construct (dscCfaE) and as a chimeric construct (Chimera) in which dscCfaE replaces the A1 domain of the cholera toxin A subunit and assembles non-covalently with the pentamer of heat-labile toxin B (LTB). Subjects received three ID vaccinations three weeks apart with either dscCfaE (1, 5, and 25 µg) or Chimera (2.6 and 12.9 µg) with and without 0.1 µg of mLT. Subjects were monitored for local and systemic adverse events. Immunogenicity was evaluated by serum and antibody-secreting cell (ASC) responses.

RESULTS

The vaccine was well-tolerated with predominantly mild and moderate local vaccine site reactions characterized by erythema, induration and post-inflammatory hyperpigmentation. High rates of serologic and ASC responses were seen across study groups with the most robust responses observed in subjects receiving 25 µg of dscCfaE with 0.1 mcg of LT(R192G).

CONCLUSION

Both ETEC adhesin vaccine prototypes were safe and immunogenic when co-administered with mLT by the ID route. The observed immune responses induced with the high dose of dscCfaE and mLT warrant further assessment in a controlled human infection model.

Clinical and regulatory development strategies for Shigella vaccines intended for children younger than 5 years in low-income and middle-income countries

Shigellosis causes considerable public health burden, leading to excess deaths as well as acute and chronic consequences, particularly among children living in low-income and middle-income countries (LMICs). Several Shigella vaccine candidates are advancing in clinical trials and offer promise. Although multiple target populations might benefit from a Shigella vaccine, the primary strategic goal of WHO is to accelerate the development and accessibility of safe, effective, and affordable Shigella vaccines that reduce mortality and morbidity in children younger than 5 years living in LMICs. WHO consulted with regulators and policy makers at national, regional, and global levels to evaluate pathways that could accelerate regulatory approval in this priority population. Special consideration was given to surrogate efficacy biomarkers, the role of controlled human infection models, and the establishment of correlates of protection. A field efficacy study in children younger than 5 years in LMICs is needed to ensure introduction in this priority population.

GMP manufacture of Shigella flexneri 2a Artificial Invaplex (InvaplexAR) and evaluation in a Phase 1 Open-label, dose escalating study administered intranasally to healthy, adult volunteers

Shigella species cause severe disease among travelers to, and children living in, endemic countries. Although significant efforts have been made to improve sanitation, increased antibiotic resistance and other factors suggest an effective vaccine is a critical need. Artificial Invaplex (InvaplexAR) is a subunit vaccine approach complexing Shigella LPS with invasion plasmid antigens. In pre-clinical studies, the InvaplexAR vaccine demonstrated increased immunogenicity as compared to the first generation product and was subsequently manufactured under cGMP for clinical testing in a first-in-human Phase 1 study. The primary objective of this study was the safety of S. flexneri 2a InvaplexAR given by intranasal (IN) immunization (without adjuvant) in a single-center, open-label, dose-escalating Phase 1 trial and secondarily to assess immunogenicity to identify a dose of InvaplexAR for subsequent clinical evaluations. Subjects received three IN immunizations of InvaplexAR, two weeks apart, in increasing dose cohorts (10 µg, 50 µg, 250 µg, and 500 μg). Adverse events were monitored using symptom surveillance, memory aids, and targeted physical exams. Samples were collected throughout the study to investigate vaccine-induced systemic and mucosal immune responses. There were no adverse events that met vaccination-stopping criteria. The majority (96%) of vaccine-related adverse events were mild in severity (most commonly nasal congestion, rhinorrhea, and post-nasal drip). Vaccination with InvaplexAR induced anti-LPS serum IgG responses and anti-Invaplex IgA and IgG antibody secreting cell (ASC) responses at vaccine doses ≥250 µg. Additionally, mucosal immune responses and functional antibody responses were seen from the serum bactericidal assay measurements. Notably, the responder rates and the kinetics of ASCs and antibody lymphocyte secretion (ALS) were similar, suggesting that either assay may be employed to identify IgG and IgA secreting cells. Further studies with InvaplexAR will evaluate alternative immunization routes, vaccination schedules and formulations to further optimize immunogenicity. (Clinical Trial Registry Number NCT02445963).

Preclinical Serological Signatures are Associated With Complicated Crohn's Disease Phenotype at Diagnosis

BACKGROUND

At diagnosis, up to one-third of patients with Crohn's disease (CD) have a complicated phenotype with stricturing (B2) or penetrating (B3) behavior or require early surgery. We evaluated protein biomarkers and antimicrobial antibodies in serum archived years before CD diagnosis to assess whether complicated diagnoses were associated with a specific serological signature.

METHODS

Prediagnosis serum was obtained from 201 patients with CD and 201 healthy controls. Samples were evaluated with a comprehensive panel of 1129 proteomic markers (SomaLogic) and antimicrobial antibodies. CD diagnosis and complications were defined by the International Classification of Diseases-Ninth Revision and Current Procedural Terminology codes. Cox regression models were utilized to assess the association between markers and the subsequent risk of being diagnosed with complicated CD. In addition, biological pathway and network analyses were performed.

RESULTS

Forty-seven CD subjects (24%) had a B2 (n = 36) or B3 (n = 9) phenotype or CD-related surgery (n = 2) at diagnosis. Subjects presenting with complicated CD at diagnosis had higher levels of antimicrobial antibodies six years before diagnosis as compared with those diagnosed with noncomplicated CD. Twenty-two protein biomarkers (reflecting inflammatory, fibrosis, and tissue protection markers) were found to be associated with complicated CD. Pathway analysis of the altered protein biomarkers identified higher activation of the innate immune system and complement or coagulation cascades up to six years before diagnosis in complicated CD.

CONCLUSIONS

Proteins and antimicrobial antibodies associated with dysregulated innate immunity, excessive adaptive response to microbial antigens, and fibrosis precede and predict a complicated phenotype at the time of diagnosis in CD patients.

Anti-Integrin αvβ6 Autoantibodies Are a Novel Biomarker That Antedate Ulcerative Colitis

BACKGROUND & AIMS

Better biomarkers for prediction of ulcerative colitis (UC) development and prognostication are needed. Anti-integrin αvβ6 (anti-αvβ6) autoantibodies have been described in patients with UC. We tested for the presence of anti-αvβ6 antibodies in the preclinical phase of UC and studied their association with disease-related outcomes after diagnosis.

METHODS

Anti-αvβ6 autoantibodies were measured in 4 longitudinal serum samples collected from 82 subjects who later developed UC and 82 matched controls from a Department of Defense preclinical cohort (PREDICTS [Proteomic Evaluation and Discovery in an IBD Cohort of Tri-service Subjects]). In a distinct, external validation cohort (Crohn's and Colitis Canada Genetic Environmental Microbial project cohort), we tested 12 pre-UC subjects and 49 matched controls. Furthermore, anti-αvβ6 autoantibodies were measured in 2 incident UC cohorts (COMPASS [Comprehensive Care for the Recently Diagnosed IBD Patients], n = 55 and OSCCAR [Ocean State Crohn's and Colitis Area Registry], n = 104) and associations between anti-αvβ6 autoantibodies and UC-related outcomes were defined using Cox proportional hazards model.

RESULTS

Anti-αvβ6 autoantibodies were significantly higher among individuals who developed UC compared with controls up to 10 years before diagnosis in PREDICTS. The anti-αvβ6 autoantibody seropositivity was 12.2% 10 years before diagnosis and increased to 52.4% at the time of diagnosis in subjects who developed UC compared with 2.7% in controls across the 4 time points. Anti-αvβ6 autoantibodies predicted UC development with an area under the curve of at least 0.8 up to 10 years before diagnosis. The presence of anti-αvβ6 autoantibodies in preclinical UC samples was validated in the GEM cohort. Finally, high anti-αvβ6 autoantibodies was associated with a composite of adverse UC outcomes, including hospitalization, disease extension, colectomy, systemic steroid use, and/or escalation to biologic therapy in recently diagnosed UC.

CONCLUSIONS

Anti-integrin αvβ6 autoantibodies precede the clinical diagnosis of UC by up to 10 years and are associated with adverse UC-related outcomes.

Challenges and opportunities in developing a Shigella-containing combination vaccine for children in low- and middle-income countries: Report of an expert convening

The gram-negative bacterium Shigella is an enteric pathogen responsible for significant morbidity and mortality due primarily to severe diarrhea and dysentery, mainly among children younger than five years of age living in low- and middle-income countries (LMICs). Long considered a priority target for vaccine development, recent scientific advances have led to a number of promising Shigella vaccine candidates now entering advanced stages of clinical testing. Yet, there is no guarantee that even a highly efficacious Shigella vaccine will be recommended, prioritized, purchased, and widely adopted-especially if it requires additional doses in the immunization schedule and/or visits within the immunization program. This uncertainty is due to a variety of factors, including continuing declines in Shigella-specific and overall diarrheal disease mortality rates, the increasing complexity and cost of infant immunization programs in LMICs, and the recent availability of other high-priority vaccines. Since combining a Shigella vaccine with an existing infant vaccine would conceivably increase its attractiveness, there is a need to systematically consider the challenges determining the public health value, clinical development, manufacturing, licensure, policy recommendations, and financing for a Shigella-containing combination vaccine. The international non-governmental health organization PATH convened an independent panel of 34 subject matter experts across academic, industry, philanthropic, and global health sectors to discuss hypothetical combinations of a notional parenteral Shigella vaccine with three existing vaccines in order to begin exploring the challenges associated with their development. The resulting insights and recommendations from this meeting contribute to PATH's broader effort to evaluate the public health value of potential Shigella vaccines. They may also help guide future combination vaccine development efforts more broadly.

Neutralizing Anti-Granulocyte Macrophage-Colony Stimulating Factor Autoantibodies Recognize Post-Translational Glycosylations on Granulocyte Macrophage-Colony Stimulating Factor Years Before Diagnosis and Predict Complicated Crohn's Disease

BACKGROUND & AIMS

Anti-granulocyte macrophage-colony stimulating factor autoantibodies (aGMAbs) are detected in patients with ileal Crohn's disease (CD). Their induction and mode of action during or before disease are not well understood. We aimed to investigate the underlying mechanisms associated with aGMAb induction, from functional orientation to recognized epitopes, for their impact on intestinal immune homeostasis and use as a predictive biomarker for complicated CD.

METHODS

We characterized using enzyme-linked immunosorbent assay naturally occurring aGMAbs in longitudinal serum samples from patients archived before the diagnosis of CD (n = 220) as well as from 400 healthy individuals (matched controls) as part of the US Defense Medical Surveillance System. We used biochemical, cellular, and transcriptional analysis to uncover a mechanism that governs the impaired immune balance in CD mucosa after diagnosis.

RESULTS

Neutralizing aGMAbs were found to be specific for post-translational glycosylation on granulocyte macrophage-colony stimulating factor (GM-CSF), detectable years before diagnosis, and associated with complicated CD at presentation. Glycosylation of GM-CSF was altered in patients with CD, and aGMAb affected myeloid homeostasis and promoted group 1 innate lymphoid cells. Perturbations in immune homeostasis preceded the diagnosis in the serum of patients with CD presenting with aGMAb and were detectable in the noninflamed CD mucosa.

CONCLUSIONS

Anti-GMAbs predict the diagnosis of complicated CD long before the diagnosis of disease, recognize uniquely glycosylated epitopes, and impair myeloid cell and innate lymphoid cell balance associated with altered intestinal immune homeostasis.

The role of state breastfeeding laws and programs on exclusive breastfeeding practice among mothers in the special supplemental nutrition program for Women, Infants, and Children (WIC)

Background

It is unclear if state laws supporting breastfeeding are associated with exclusive breastfeeding (EBF) practice among low-income mothers participating in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). The main objectives of our study were to assess the relationship between such laws and EBF among WIC-participating mothers and to assess whether this association varied by employment status. We also assessed how mother’s exposure to WIC breastfeeding consultation was associated with EBF.

Methods

A cross-sectional study was conducted across seven WIC program locations (i.e., Georgia, Massachusetts, Nevada, Pennsylvania, Wisconsin, Wyoming, Chickasaw Nation) between July–August 2020. Data were collected using convenient sampling from each program location and surveys were administered electronically or on paper to WIC-participating mothers. We restricted our analysis to data from 1161 WIC-participating mothers with infants aged zero to five months old. Multivariable mixed models were used to estimate the relationship between our exposures of interest (i.e., number of laws supporting breastfeeding, employment-related breastfeeding laws, WIC breastfeeding consultation) and EBF, while controlling for potential confounders and accounting for clustering by program location. Effect modification by employment status was assessed on the additive and multiplicative scales.

Results

Among WIC-participating mothers living in program locations with no employment-related breastfeeding laws, EBF was 26% less prevalent for employed mothers compared to unemployed mothers (adjusted prevalence ratios [aPR]: 0.74, 95% CI: 0.67,0.83). Among all mothers, a one-unit increase in laws supporting breastfeeding was not associated with EBF (aPR: 0.88, 95% CI: 0.71,1.10). However, among employed mothers, living in areas with more employment-related laws was associated with a higher prevalence of EBF (aPR: 1.43, 95% CI: 0.83, 2.44). Infants whose mothers received a WIC breastfeeding consultation had 33% higher prevalence of being exclusively breastfed compared to infants whose mothers did not receive a WIC breastfeeding consultation (aPR: 1.33, 95% CI: 1.05,1.70).

Conclusions

Infants whose WIC-participating mothers were employed, were less likely to be exclusively breastfed, but our effect modification analyses showed that laws supporting breastfeeding at the workplace may promote EBF among employed women. EBF was more prevalent among mothers who received a WIC breastfeeding consultation compared to those who did not receive such a consultation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13006-022-00490-9.

Serological Biomarkers of Progression towards Diagnosis of Rheumatoid Arthritis in Active Component Military Personnel

OBJECTIVE

Our aim was to identify a panel of serum biomarkers that could specifically identify imminent cases of RA prior to diagnosis.

METHODS

Serum samples collected at 4 timepoints were obtained from active component US military personnel, including 157 anti-citrullinated protein antibody seropositive and 50 seronegative RA cases, 100 reactive arthritis (ReA) cases, and 76 healthy controls. The cohorts were split into two phases, with samples tested on independent proteomic platforms. Classification models of RA diagnosis based on samples from within 6 months before diagnosis were developed in univariate analyses and from multivariate random forest modeling utilizing training and test sample sets within each phase.

RESULTS

Increases in serum analytes, including CRP, SAA, and soluble programmed cell death receptor-1 (sPD-1), could be observed in seropositive RA cases at the timepoint closest to diagnosis, up to several years earlier. Only a small fraction of RA cases had levels above the 95^th percentile of healthy control levels until within 6 months of diagnosis. For classification of RA diagnosis based on samples from within 6 months before diagnosis, sPD-1 per se provided the best specificity compared to ReA cases (>89%), with sensitivity of 48% for RA classification. An 8-analyte model provided superior sensitivity of 69% with comparable specificity relative to ReA (>82%).

CONCLUSIONS

We have demonstrated that imminent diagnosis of RA could be classified with high specificity for healthy controls and ReA cases based on a panel of cytokines measured in serum samples collected within 6 months before actual diagnosis.

Critical Needs in Advancing Shigella Vaccines for Global Health

Advancing new O-antigen-based Shigella vaccines is critically dependent on development of an international standard serum and harmonized ELISA, demonstration of field efficacy in young children in low- and middle-income countries, and early engagement with regulators and policy makers.

From Kiyoshi Shiga to Present-Day Shigella Vaccines: A Historical Narrative Review

We are at an exciting moment in time with the advancement of many vaccines, including a shigella vaccine for the world. It is instructive to look at the long road that some vaccines have traveled to recognize the remarkable accomplishments of those who were pioneers, appreciate the evolution of scientific and applied technology, and inform the future history of a vaccine that would have great potential for global health. To achieve this valuable retrospective, a narrative historical literature review was undertaken utilizing PubMed and Embase databases with relevant search terms. Retrieved articles were reviewed and information was organized into historical themes, landmark discoveries, and important vaccine development parallels. The literature reviewed was synthesized into major eras of shigella vaccine development from pathogen discovery and first attempts to empirical approaches of killed whole-cell and live-attenuated approaches, and a modern era that applied recombinant DNA engineering and structural vaccinology. The history of shigella vaccine development has largely followed the evolutionary path of vaccine development over the last 120 years, but with important lessons learned that should be considered as we embark on the future chapters of bringing to the world a safe and effective vaccine for global health.

Military and Civilian Sector Practice Patterns for Short-Term Travelers' Diarrhea Self-Treatment in Adults

The Deployment and Travel Medicine Knowledge, Attitude, Practice and Outcomes Study investigates the various clinician and traveler contributions to medical outcomes within the U.S. Military Health System. Travelers' diarrhea is among the most common travel-related illnesses, making travelers' diarrhea self-treatment (TDST) important for traveler health. A cohort of 80,214 adult travelers receiving malaria chemoprophylaxis for less than 6 weeks of travel were identified within the U.S. Department of Defense Military Health System Data Repository. Associated prescriptions for TDST medications within 2 weeks of chemoprophylaxis prescriptions were identified. Prescription patterns were compared by service member versus beneficiary status and site of care, military facility versus civilian facility. At military facilities, medical provider demographics were analyzed by clinical specialty and categorized as travel medicine specialists versus nonspecialists. Overall, there was low prescribing of TDST, particularly among civilian providers and military nonspecialists, despite guidelines recommending self-treatment of moderate to severe travelers' diarrhea. This practice gap was largest among service member travelers, but also existed for beneficiaries. Compared with nonspecialists, military travel medicine specialists were more likely to prescribe a combination of an antibiotic and antimotility agent to beneficiaries, more likely to provide any form of TDST to service members, and more likely to prescribe azithromycin than quinolones when using antibiotics. Our study suggests that enhancing provider knowledge and use of travelers' diarrhea treatment recommendations combined with improved access to formal travel medicine services may be important to increase the quality of care.

TaqMan Array Card testing of participant-collected stool smears to determine the pathogen-specific epidemiology of travellers' diarrhoea†

BACKGROUND

We assessed the compliance with self-collection of stool smears on Whatman® FTA® Elute Card (FTA Card) and detection of travellers' diarrhoea (TD)-associated pathogens by using a quantitative Polymerase Chain Reaction (PCR) assay [customized TaqMan® array card (TAC)] in a prospective, observational cohort of travellers.

METHODS

Enrolled travellers documented symptoms on a travel diary and collected an FTA Card during a diarrhoeal episode, or at the end of travel if they remained asymptomatic. TAC testing was performed on FTA Cards from TD cases and 1:1 matched asymptomatic controls and 1:1 matched loose stool cases that did not meet TD criteria. Odds ratios were used to determine the association between detected pathogens and TD.

RESULTS

Of 2456 travellers, 484 (19.7%) completed an illness diary and met TD criteria, and 257 (53.1%) collected an FTA Card during the TD episode. FTA Cards were stored for a median of 2 years at room temperature (IQR: 1-4 years) before extraction and testing. The overall TAC detection rate in TD cases was 58.8% (95% CI: 52.5-64.8). Enterotoxigenic Escherichia coli was the most common pathogen in TD cases (26.8%), and 3.5% of samples were positive for norovirus. The odds of detecting TD-associated pathogens in 231 matched cases and asymptomatic controls were 5.4 (95% CI: 3.6-8.1) and 2.0 (95% CI: 1.1-3.7) in 121 matched TD and loose stool cases (P < 0.05). Enteroaggregative E. coli was the most common pathogen detected in asymptomatic controls and loose stool cases. Detection of diarrhoeagenic E. coli, Shigella/enteroinvasive E. coli and Campylobacter spp. was significantly associated with TD.

CONCLUSION

FTA Cards are a useful adjunct to traditional stool collection methods for evaluating the pathogen-specific epidemiology of TD in austere environments. Qualitative detection of pathogens was associated with TD. Measures to improve compliance and quality of FTA Card collection with decreased storage duration may further optimize detection.

A disease severity scale for the evaluation of vaccine and other preventive or therapeutic interventions for travellers' diarrhoea

BACKGROUND

Travellers' diarrhoea (TD) is the most common travel-related illness with an estimated 10 million people afflicted annually. Outcome measures to assess the efficacy of primary and secondary TD interventions were historically based on diarrhoea frequency with ≥1 associated gastrointestinal symptom. Furthermore, efficacy determination is often made on the presence or absence of TD, rather than on TD illness severity. Current severity classifications are based on subjective consideration of impact of illness on activity. We sought to develop a standardized scoring system to characterize TD severity to potentially apply as a secondary outcome in future field studies.

METHODS

Data on multiple signs and symptoms were obtained from a previously published multisite TD treatment trial conducted by the US Department of Defense (TrEAT TD). Correlation, regression and multiple correspondence analyses were performed to assess impact on activity and a TD severity score was established.

RESULTS

Numerous signs and symptoms were associated with impaired function, with malaise and nausea most strongly associated [odds ratio (OR) 5.9-44.3, P < 0.0001 and OR 2.8-37.1, P < 0.0001, respectively). Based on co-varying symptomatology, a TD severity score accounting for diarrhoea frequency in addition to several signs and symptoms was a better predictor of negative impact on function than any single sign/symptom (X2 = 127.16, P < 0.001). Additionally, there was a significant difference (P < 0.0001) in the mean TD severity score between those with acute watery diarrhoea (3.9 ± 1.9) and those with dysentery or acute febrile illness (6.2 ± 2.0).

CONCLUSIONS

The newly developed disease severity score better predicted a negative impact on activity due to TD than did any single sign or symptom. Incorporating multiple parameters into the TD severity score better captures illness severity and moves the field towards current recommendations for TD management by considering symptoms with high functional impact. Further validation of this score is needed in non-military travellers and other settings.

What's new in travellers' diarrhoea: updates on epidemiology, diagnostics, treatment and long-term consequences

BACKGROUND

Travellers' diarrhoea (TD) is the most common clinical syndrome affecting travellers. This narrative review summarizes key discoveries reported in the last two years related to TD and suggests areas for future research.

METHODS

A PubMed literature search was conducted for novel data in TD research published between 12 January 2018 and 12 January 2020. Inclusion was based on contribution to epidemiology, aetiology, diagnostics, management and long-term consequences and relevance to public health, discovery and clinical practice.

RESULTS

The initial literature search yielded 118 articles. We retrieved 72 and reviewed 31 articles for inclusion. The findings support our understanding that TD incidence varies by traveller group and environment with students and military-travel remaining moderately high risk, and control of food and water in mass gathering events remain an important goal. The growth of culture-independent testing has led to a continued detection of previously known pathogens, but also an increased detection frequency of norovirus. Another consequence is the increase in multi-pathogen infections, which require consideration of clinical, epidemiological and diagnostic data. Fluoroquinolone resistant rates continue to rise. New data on non-absorbable antibiotics continue to emerge, offering a potential alternative to current recommendations (azithromycin and fluoroquinolones), but are not recommended for febrile diarrhoea or dysentery or regions/itineraries where invasive pathogens are likely to cause illness. Recent studies investigated the interaction of the microbiome in TD prevention and consequences, and while discriminating features were identified, much uncertainty remains. The prevalence of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) acquisition and carriage is increasing. Finally, continued research documents the post-infectious consequences, whereas mechanisms of reactive arthritis and post-infectious IBS necessitate further investigation.

CONCLUSIONS

Globally, TD remains an important travel health issue and advances in our understanding continue. More research is needed to mitigate risk factors where possible and develop risk-based management strategies to reduce antibiotic usage and its attendant consequences.

World Health Organization Expert Working Group: Recommendations for assessing morbidity associated with enteric pathogens

BACKGROUND

Diarrhoeal infections are one of the leading causes of child's mortality and morbidity. Vaccines against Shigella, enterotoxigenic E. coli (ETEC), norovirus and invasive non-typhoidal Salmonella are in clinical development, however, their full value in terms of short and long-term health and socio-economic burden needs to be evaluated and communicated, to rationalise investment in vaccine development, and deployment. While estimates of mortality of enteric infections exist, the long-term morbidity estimates are scarce and have not been systematically collected.

METHODS

The World Health Organization (WHO) has convened a Burden of Enteric Diseases Morbidity Working Group (BoED MWG) who identified key workstreams needed to characterise the morbidity burden of enteric infections. The group also identified four criteria for the prioritisation of pathogens of which impact on long-term morbidity needs to be assessed.

RESULTS

The BoED MWG suggested to identify and analyse the individual level data from historical datasets to estimate the impact of enteric infections and confounders on long-term morbidity, including growth faltering and cognitive impairment in children (workstream 1); to conduct a systematic review of evidence on the association of aetiology specific diarrhoea with short- and long- term impact on growth, including stunting, and possibly cognitive impairment in children, while accounting for potential confounders (workstream 2); and to conduct a systematic review of evidence on the association of aetiology specific diarrhoea with short- and long- term impact on health outcomes in adults. The experts prioritised four pathogens for this work: Campylobacter jejuni, ETEC (LT or ST), norovirus (G1 or G2), and Shigella (dysenteriae, flexneri, sonnei).

CONCLUSIONS

The proposed work will contribute to improving the understanding of the impact of enteric pathogens on long-term morbidity. The timing of this work is critical as all four pathogens have vaccine candidates in the clinical pipeline and decisions about investments in development, manufacturing or vaccine procurement and use are expected to be made soon.

Safety and immunogenicity of intramuscularly administered CS6 subunit vaccine with a modified heat-labile enterotoxin from enterotoxigenic Escherichia coli

INTRODUCTION

Enterotoxigenic Escherichia coli (ETEC) is a common cause of infectious diarrhoea and a leading cause of morbidity and mortality in children living in resource-limited settings. It is also the leading cause of travellers' diarrhoea among civilian and military travellers. Its dual importance in global public health and travel medicine highlights the need for an effective vaccine. ETEC express colonization factors (CFs) that mediate adherence to the small intestine. An epidemiologically prevalent CF is coli surface antigen 6 (CS6). We assessed the safety and immunogenicity of a CS6-targeted candidate vaccine, CssBA, co-administered intramuscularly with the double-mutant heat-labile enterotoxin, dmLT [LT(R192G/L211A)].

METHODS

This was an open-label trial. Fifty subjects received three intramuscular injections (Days 1, 22 and 43) of CssBA alone (5 µg), dmLT alone (0.1 µg) or CssBA (5, 15, 45 µg) + dmLT (0.1 and 0.5 µg). Subjects were actively monitored for adverse events for 28 days following the third vaccination. Antibody responses (IgG and IgA) were characterized in the serum and from lymphocyte supernatants (ALS) to CS6 and the native ETEC heat labile enterotoxin, LT.

RESULTS

Across all dose cohorts, the vaccine was safe and well-tolerated with no vaccine-related severe or serious adverse events. Among vaccine-related adverse events, a majority (98%) were mild with 79% being short-lived vaccine site reactions. Robust antibody responses were induced in a dose-dependent manner with a clear dmLT adjuvant effect. Response rates in subjects receiving 45 µg CssBA and 0.5 µg dmLT ranged from 50 to 100% across assays.

CONCLUSION

This is the first study to demonstrate the safety and immunogenicity of CssBA and/or dmLT administered intramuscularly. Co-administration of the two components induced robust immune responses to CS6 and LT, paving the way for future studies to evaluate the efficacy of this vaccine target and development of a multivalent, subunit ETEC vaccine.

A prospective observational study describing severity of acquired diarrhea among U.S. military and Western travelers participating in the Global Travelers' Diarrhea Study

BACKGROUND

Travelers' diarrhea (TD) is one of the most common illnesses affecting modern-day travelers, including military personnel. Previous work has shown that afflicted travelers may alter their itineraries and be confined to bed rest due to symptoms, and military personnel may become incapable of completing operational requirements. Examination of signs, symptoms, and severity of diarrheagenic pathogens can inform clinical diagnosis and prioritization of future surveillance and research activities.

METHODS

Utilizing a global laboratory network, culture and molecular testing were performed in parallel at each site on a group of core pathogens, and definitions for acute diarrhea (AD), severe AD, acute gastroenteritis (AGE), and severe AGE were determined using data elements in the modified Vesikari scale. We included 210 cases of TD reporting all variables of interest in our severity assessment analysis.

RESULTS

Out of all cases, 156/210 (74%) met criteria for severe AD and 35/210 (17%) for severe AGE. Examination of severity by pathogen revealed that, at non-military sites, 17/19 (89%) of enteropathogenic Escherichia coli (E. coli) (EPEC) infections, 28/32 (88%) of enterotoxigenic E. coli (ETEC) infections, and 13/15 (87%) of Shigella/enteroinvasive E. coli (EIEC) infections resulted in severe AD cases. At the military site, all infections of ETEC (6/6), Shigella-EIEC (4/4), and enteroaggregative E. coli (EAEC) resulted in AD. Norovirus infections at non-military and military sites resulted in 27% (14/51) and 33% (3/9) severe AGE cases, respectively.

CONCLUSIONS

This study found a high percentage of participants enrolled at both military and non-military sites experienced severe AD with concerning numbers of severe cases at non-military sites reporting hospitalization and reductions in performance. Since travelers with mild TD symptoms are less likely to present to health care workers than those with more severe TD, there is a potential selection bias in this study that may have overestimated the proportion of more severe outcomes among all individuals who could have participated in the GTD study. Future research should examine other covariates among pathogen and host, such as treatment and comorbid conditions, that may contribute to the presence of signs and symptoms and their severity.

Global diarrhoea-associated mortality estimates and models in children: Recommendations for dataset and study selection

BACKGROUND

Multiple factors contribute to variation in disease burden, including the type and quality of data, and inherent properties of the models used. Understanding how these factors affect mortality estimates is crucial, especially in the context of public health decision making. We examine how the quality of the studies selected to provide mortality data, influence estimates of burden and provide recommendations about the inclusion of studies and datasets to calculate mortality estimates.

METHODS

To determine how mortality estimates are affected by the data used to generate model outputs, we compared the studies used by The Institute of Health Metrics and Evaluation (IHME) and Maternal and Child Epidemiology Estimation (MCEE) modelling groups to generate enterotoxigenic Escherichia coli (ETEC) and Shigella-associated mortality estimates for 2016. Guided by an expert WHO Working Group, we applied a modified Newcastle-Ottawa Scale (NOS) to evaluate the quality of studies used by both modelling groups.

RESULTS

IHME and MCEE used different sets of ETEC and Shigella studies in their models and the majority of studies were high quality. The distribution of the NOS scores was similar between the two modelling groups. We observed an overrepresentation of studies from some countries in SEAR, AFR and WPR compared to other WHO regions.

CONCLUSION

We identified key differences in study inclusion and exclusion criteria used by IHME and MCEE and discuss their impact on datasets used to generate diarrhoea-associated mortality estimates. Based on these observations, we provide a set of recommendations for future estimates of mortality associated with enteric diseases.

Fecal Microbiota Functional Gene Effects Related to Single-Dose Antibiotic Treatment of Travelers' Diarrhea

Background

Travelers' diarrhea (TD) is common among military personnel deployed to tropical and subtropical regions. It remains unclear how TD and subsequent antibiotic treatment impact the resident microflora within the gut, especially given increased prevalence of antibiotic resistance among enteric pathogens and acquisition of multidrug-resistant organisms. We examined functional properties of the fecal microflora in response to TD, along with subsequent antibiotic treatment.

Methods

Fecal samples from US and UK military service members deployed to Djibouti, Kenya, and Honduras who presented with acute watery diarrhea were collected. A sample was collected at acute presentation to the clinic (day 0, before antibiotics), as well as 7 and/or 21 days following a single dose of antibiotics (azithromycin [500 mg], levofloxacin [500 mg], or rifaximin [1650 mg], all with loperamide). Each stool sample underwent culture and TaqMan reverse transcription polymerase chain reaction analyses for pathogen and antibiotic resistance gene detection. Purified DNA from each sample was analyzed using the HumiChip3.1 functional gene array.

Results

In total, 108 day 1 samples, 50 day 7 samples, and 94 day 21 samples were available for analysis from 119 subjects. Geographic location and disease severity were associated with distinct functional compositions of fecal samples. There were no overt functional differences between pre- and postantibiotic treatment samples, nor was there increased acquisition of antibiotic resistance determinants for any of the antibiotic regimens.

Conclusions

These results indicate that single-dose antibiotic regimens may not drastically alter the functional or antibiotic resistance composition of fecal microflora, which should inform clinical practice guidelines and antimicrobial stewardship.

Clinical Trials Registration Number

NCT01618591.

Human challenge study with a Shigella bioconjugate vaccine: Analyses of clinical efficacy and correlate of protection

BACKGROUND

Shigellosis is a major cause of moderate to severe diarrhoea and dysentery in children under 5 years of age in low and middle-income countries. The Flexyn2a vaccine conjugates the O-polysaccharide of Shigella flexneri 2a to Pseudomonas aeruginosa exotoxin A. We describe a Phase 2b proof-of-concept challenge study that evaluated safety, immunogenicity, and efficacy of the Flexyn2a vaccine to protect against shigellosis.

METHODS

In this randomized, double blind, placebo-controlled trial, healthy adults were randomized 1:1 to receive Flexyn2a (10 µg) or placebo intramuscularly, twice, 4 weeks apart, followed by challenge 4 weeks later with 1500 colony forming units (CFUs) of S. flexneri 2a strain 2457T. The primary outcome was vaccine-induced protection. S. flexneri 2a lipopolysaccharide (LPS)-specific immune responses were assessed.

FINDINGS

Sixty-seven subjects were enrolled, 34 received vaccine and 33 placebo. The vaccine was well tolerated; the majority of adverse events were mild in nature. Thirty vaccinees and 29 placebo recipients received the S. flexneri 2a challenge. Vaccination resulted in a 30.2% reduction in shigellosis compared with placebo (13/30 vs. 18/29; p = 0.11; 95% CI -15 to 62.6). Vaccine efficacy was more robust against severe disease, reaching 51.7% (p = 0.015, 95% CI 5.3 to 77.9) against moderate/severe diarrhoea or dysentery concurrent with fever or severe enteric symptoms and 72.4% (p = 0.07) against more severe diarrhoea (≥10 lose stools or ≥1000 g loose stools/24 h). Vaccinated subjects were less likely to need early antibiotic intervention following challenge (protective efficacy 51.7%, p = 0.01; 95% CI 9 to 76.8). In those who developed shigellosis, vaccinated subjects had a lower disease severity score (p = 0.002) than placebo-recipients. Additionally, LPS-specific serum IgG responses in Flexyn2a recipients were associated with protection against disease (p = 0.0016) and with a decreased shigellosis disease score (p = 0.002).

INTERPRETATION

The Flexyn2a bioconjugate vaccine was immunogenic, well tolerated and protected against severe illness after Shigella challenge and is a promising Shigella vaccine construct. We identified a strong association between anti-S. flexneri 2a serum IgG and a reduction in disease outcomes. (Clinicaltrials.gov, NCT02646371.) FUNDING: Funding for this study was through a grant from the Wellcome Trust.

Immune response characterization in a human challenge study with a Shigella flexneri 2a bioconjugate vaccine

BACKGROUND

Diarrheal diseases are a leading cause of global morbidity and mortality affecting all ages, but especially children under the age of five in resource-limited settings. Shigella is a leading contributor to diarrheal diseases caused by bacterial pathogens and is considered a significant antimicrobial resistance threat. While improvements in hygiene, and access to clean water help as control measures, vaccination remains one of the most viable options for significantly reducing morbidity and mortality.

METHODS

Flexyn2a is a bioconjugate vaccine manufactured using novel conjugation methodologies enzymatically linking the O-polysaccharide of S. flexneri 2a to exotoxin A of Pseudomonas aeruginosa. The protective capacity of Flexyn2a was assessed in a controlled human infection model after two intramuscular immunizations. Immune responses pre- and post-immunization and/or infection were investigated and are described here.

FINDINGS

Flexyn2a induced lipopolysaccharide (LPS)-specific serum IgG responses post-immunization which were associated with protection against shigellosis. Additionally, several other immune parameters, including memory B cell responses, bactericidal antibodies and serum IgA, were also elevated in vaccinees protected against shigellosis. Immunization with Flexyn2a also induced gut-homing, LPS-specific IgG and IgA secreting B cells, indicating the vaccine induced immune effectors functioning at the site of intestinal infection.

INTERPRETATION

Collectively, the results of these immunological investigations provide insights into protective immune mechanisms post-immunization with Flexyn2a which can be used to further guide vaccine development and may have applicability to the larger Shigella vaccine field.

FUNDING

Funding for this study was provided through a Wellcome Trust grant.

A Retrospective Case Series of Thiamine Deficiency in Non-Alcoholic Hospitalized Veterans: An Important Cause of Delirium and Falling?

Thiamine deficiency (TD) in non-alcoholic hospitalized patients causes a variety of non-specific symptoms. Studies suggest it is not rare in acutely and chronically ill individuals in high income countries and is underdiagnosed. Our aim is to demonstrate data which help define the risk factors and constellation of symptoms of TD in this population. We describe 36 cases of TD in hospitalized non-alcoholic veterans over 5 years. Clinical and laboratory data were extracted by chart review +/− 4 weeks of plasma thiamine level 7 nmol/L or less. Ninety-seven percent had two or more chronic inflammatory conditions (CICs) and 83% had one or more acute inflammatory conditions (AICs). Of possible etiologies of TD 97% had two or more of: insufficient intake, inflammatory stress, or increased losses. Seventy-five percent experienced 5% or more weight loss. Ninety-two percent had symptoms with the most common being weakness or falling (75%) followed by neuropsychiatric manifestations (72%), gastrointestinal dysfunction (53%), and ataxia (42%). We conclude that TD is underdiagnosed in this population with consequent morbidity and mortality. TD likely develops because of inflammatory stress from CIC’s compounded by AIC’s combined with decreased energy intake or increased nutrient losses.

The interrelationship between water access, exclusive breastfeeding and diarrhea in children: a cross-sectional assessment across 19 African countries

Background

Access to an improved water supply and practicing exclusive breastfeeding are essential for improving maternal and child health outcomes. However, few studies have been equipped to assess the interdependencies between access to improved water, practicing exclusive breastfeeding, and child health. The primary aim of our study was to assess whether access to an improved water supply and water-fetching were associated with mothers’ practice of exclusive breastfeeding.

Methods

We analyzed data on 247 090 mothers with children 5 months old or less using Multiple Indicator Cluster Surveys from 19 African countries. Multivariable logistic regression was used to estimate the relationship between our exposures and exclusive breastfeeding practice, while meta-analytic methods were used to pool adjusted estimates across 19 countries.

Results

The prevalence of exclusive breastfeeding ranged from 22% in Nigeria to 70% in Malawi. Pooled results showed water-fetching was not associated with exclusive breastfeeding (adjusted prevalence odds ratios (aPOR) = 1.04, 95% confidence interval (CI) = 0.89, 1.21). Access to an improved water source was also not associated with exclusive breastfeeding (aPOR = 1.06, 95% CI = 0.94, 1.21). Across all countries many women were spending a significant amount of time water-fetching each day (mean time varied from 20 minutes in Ghana to 115 minutes in Mauritania). Exclusively breastfed children had 33% lower odds of diarrhea than those who were not exclusively breastfed (aPOR = 0.67, 95% CI = 0.56, 0.78).

Conclusion

Our study is the first to assess the relationship between access to improved water supply, water-fetching and exclusive breastfeeding. We found that access to water supply and time spent by mothers fetching water were not associated with exclusive breastfeeding practice, even though mothers spent significant time fetching water.

The interrelationship between water access, exclusive breastfeeding and diarrhea in children: a cross-sectional assessment across 19 African countries

BACKGROUND

Access to an improved water supply and practicing exclusive breastfeeding are essential for improving maternal and child health outcomes. However, few studies have been equipped to assess the interdependencies between access to improved water, practicing exclusive breastfeeding, and child health. The primary aim of our study was to assess whether access to an improved water supply and water-fetching were associated with mothers' practice of exclusive breastfeeding.

METHODS

We analyzed data on 247 090 mothers with children 5 months old or less using Multiple Indicator Cluster Surveys from 19 African countries. Multivariable logistic regression was used to estimate the relationship between our exposures and exclusive breastfeeding practice, while meta-analytic methods were used to pool adjusted estimates across 19 countries.

RESULTS

The prevalence of exclusive breastfeeding ranged from 22% in Nigeria to 70% in Malawi. Pooled results showed water-fetching was not associated with exclusive breastfeeding (adjusted prevalence odds ratios (aPOR) = 1.04, 95% confidence interval (CI) = 0.89, 1.21). Access to an improved water source was also not associated with exclusive breastfeeding (aPOR = 1.06, 95% CI = 0.94, 1.21). Across all countries many women were spending a significant amount of time water-fetching each day (mean time varied from 20 minutes in Ghana to 115 minutes in Mauritania). Exclusively breastfed children had 33% lower odds of diarrhea than those who were not exclusively breastfed (aPOR = 0.67, 95% CI = 0.56, 0.78).

CONCLUSION

Our study is the first to assess the relationship between access to improved water supply, water-fetching and exclusive breastfeeding. We found that access to water supply and time spent by mothers fetching water were not associated with exclusive breastfeeding practice, even though mothers spent significant time fetching water.

Using COVID-19 cycle threshold and other lab values as predictors of hospitalization need

SARS-COV-2 (COVID-19) is a novel virus that has caused over 28 million cases worldwide and over 900,000 deaths since early 2020, rightfully being classified as a pandemic. COVID-19 is diagnosed via polymerase chain reaction testing which looks at cycle threshold (CT) values of two genes, N2 and E. This study examined CT values of COVID-positive patients at the VA hospital in Reno as well as other lab values and comorbidities to determine if any could aid clinicians in predicting the need for hospitalization and higher levels of care. Multiple variables, including N2 CT value, absolute lymphocyte count (ALC), D-dimer, erythrocyte sedimentation rate, C-reactive protein, fibrinogen, and ferritin were evaluated for potential associations with N2 CT value as well as required level of care (based on World Health Organization [WHO] ordinal score). The results suggest that patients with a N2 CT value less than 34 are four times more likely to have WHO ordinal scores of 4-8 (p = .0021) while controlling for age and comorbidities (DM, cardiac, kidney, and lung disease). Patients of age 55 or greater were 15.18 times more likely to have WHO ordinal scores of 4-8 (p = .012) controlling for N2 CT value and comorbidities. Furthermore, patients with ALC less than 1 were 5.88 times more likely to have WHO ordinal score of 4-8 (p = .00024). N2 CT values also appear to be associated with many commonly obtained markers such as ALC, white blood cell count, C-reactive protein, and D-dimer. Patients with N2 CT values less than 34 were 3.49 times more likely to have ALC values less than 1, controlling for age and comorbidities (p = .0072) while patients 55 or older were 6.66 times more likely to have ALC less than 1 (p = .027). Finally, this study confirms previous conclusions that patients with advanced age had more severe infections and thus will likely require higher levels of care.

Refinement of the CS6-expressing enterotoxigenic Escherichia coli strain B7A human challenge model: A randomized trial

Background

Human challenge models for enterotoxigenic Escherichia coli (ETEC) facilitate vaccine down-selection. The B7A (O148:H28 CS6⁺LT⁺ST⁺) strain is important for vaccine development. We sought to refine the B7A model by identifying a dose and fasting regimen consistently inducing moderate-severe diarrhea.

Methods

An initial cohort of 28 subjects was randomized (1:1:1:1) to receive B7A following an overnight fast at doses of 10⁸ or 10⁹ colony forming units (cfu) or a 90-minute fast at doses of 10⁹ or 10¹⁰ cfu. A second cohort included naïve and rechallenged subjects who had moderate-severe diarrhea and were given the target regimen. Immune responses to important ETEC antigens were assessed.

Results

Among subjects receiving 10⁸ cfu of B7A, overnight fast, or 10⁹ cfu, 90-minute fast, 42.9% (3/7) had moderate-severe diarrhea. Higher attack rates (71.4%; 5/7) occurred in subjects receiving 10⁹ cfu, overnight fast, or 10¹⁰ cfu, 90-minute fast. Upon rechallenge with 10⁹ cfu of B7A, overnight fast, 5/11 (45.5%) had moderate-severe diarrhea; the attack rate among concurrently challenge naïve subjects was 57.9% (11/19). Anti-CS6, O148 LPS and LT responses were modest across all groups.

Conclusions

An overnight fast enabled a reduction in the B7A inoculum dose; however, the attack rate was inconsistent and protection upon rechallenge was minimal.

A Multisite Network Assessment of the Epidemiology and Etiology of Acquired Diarrhea among U.S. Military and Western Travelers (Global Travelers' Diarrhea Study): A Principal Role of Norovirus among Travelers with Gastrointestinal Illness

U.S. military personnel must be ready to deploy to locations worldwide, including environments with heightened risk of infectious disease. Diarrheal illnesses continue to be among the most significant infectious disease threats to operational capability. To better prevent, detect, and respond to these threats and improve synchronization across the Department of Defense (DoD) overseas laboratory network, a multisite Global Travelers’ Diarrhea protocol was implemented with standardized case definitions and harmonized laboratory methods to identify enteric pathogens. Harmonized laboratory procedures for detection of Norovirus (NoV), enterotoxigenic Escherichia coli (ETEC), enteroaggregative E. coli, Shiga toxin–producing E. coli, enteropathogenic E. coli, Salmonella enterica, Shigella/enteroinvasive E. coli, and Campylobacter jejuni have been implemented at six DoD laboratories with surveillance sites in Egypt, Honduras, Peru, Nepal, Thailand, and Kenya. Samples from individuals traveling from wealthy to poorer countries were collected between June 2012 and May 2018, and of samples with all variables of interest available (n = 410), most participants enrolled were students (46%), tourists (26%), U.S. military personnel (13%), or other unspecified travelers (11%). One or more pathogens were detected in 59% of samples tested. Of samples tested, the most commonly detected pathogens were NoV (24%), ETEC (16%), and C. jejuni (14%), suggesting that NoV plays a larger role in travelers’ diarrhea than has previously been described. Harmonized data collection and methods will ensure identification and characterization of enteric pathogens are consistent across the DoD laboratory network, ultimately resulting in more comparable data for global assessments, preventive measures, and treatment recommendations.

Oral delivery of Hyperimmune bovine serum antibodies against CS6-expressing enterotoxigenic Escherichia coli as a prophylactic against diarrhea

BACKGROUND

. Oral administration of bovine antibodies active against enterotoxigenic Escherichia coli (ETEC) have demonstrated safety and efficacy against diarrhea in human challenge trials. The efficacy of bovine serum immunoglobulins (BSIgG) against recombinant colonization factor CS6 or whole cell ETEC strain B7A was assessed against challenge with the CS6-expressing B7A.

METHODS

. This was a randomized, double-blind, placebo-controlled trial in which healthy adults received oral hyperimmune BSIgG anti-CS6, anti-B7A whole cell killed or non-hyperimmune BSIgG (placebo) in a 1:1:1 ratio then challenged with ETEC B7A. Two days pre-challenge, volunteers began a thrice daily, seven day course of immunoprophylaxis. On day 3, subjects received 1 × 10¹⁰ CFUs of B7A. Subjects were observed for safety and the primary endpoint of moderate-severe diarrhea (MSD).

RESULTS

. A total of 59 volunteers received product and underwent ETEC challenge. The BSIgG products were well-tolerated across all subjects. Upon challenge, 14/20 (70%) placebo recipients developed MSD, compared to 12/19 (63%; p = .74) receiving anti-CS6 BSIgG and 7/20 (35%; p = .06) receiving anti-B7A BSIgG. Immune responses to the ETEC infection were modest across all groups.

CONCLUSIONS

. Bovine-derived serum antibodies appear safe and well tolerated. Antibodies derived from cattle immunized with whole cell B7A provided 50% protection against MSD following B7A challenge; however, no protection was observed in subjects receiving serum antibodies targeting CS6. The lack of observed efficacy in this group may be due to low CS6 surface expression on B7A, the high dose challenge inoculum and/or the use of serum derived antibodies versus colostrum-derived antibodies.

Performance characteristics of a quantitative PCR assay on repository stool specimens and smeared filter-paper cards

Objective

Stool repositories are a valuable resource for retrospective analyses including quantitative PCR assays to distinguish between asymptomatic shedding and clinical disease. The suitability of archival specimens for this purpose is unclear and requires assessment. We conducted a pilot study to evaluate pathogen detection by TaqMan Array Card (TAC) in travelers’ diarrhea (TD) stool specimens stored for 1–13 years, as well as the impact of transporting specimens on Whatman FTA Elute cards (FTA Cards) on detection.

Results

The positive percent agreement (PPA) for TAC on stool vs. microbiologic testing was lower than our a priori PPA estimate of 80% for most pathogens: Shigella spp. (100% [95%CI 69–100%]), enterotoxigenic E coli (ETEC) (63% [95%CI 49–75%]), Campylobacter spp. (66% [95%CI 43–85%]) and Norovirus (37% [95%CI 16–61%]). Use of the FTA card resulted in a further reduction of PPA. Our findings suggest that archival specimens may lead to insensitive detection on quantitative PCR assays due to degradation of nucleic acid with prolonged storage, although our limited sample size precluded us from evaluating the impact of storage duration on nucleic acid yield. Additional studies are needed to understand the impact of storage duration on quantitative PCR data.

Consensus Report on Shigella Controlled Human Infection Model: Clinical Endpoints

The Shigella controlled human infection model (CHIM) is valuable for assessing candidate Shigella vaccine efficacy and potentially accelerating regulatory approval. The Shigella CHIM is currently being conducted at 3 sites in the United States using Shigella flexneri 2a strain 2457T and Shigella sonnei strain 53G. Shigellosis can present variably as watery diarrhea alone or with dysentery, and can be accompanied by manifestations including fever, abdominal cramps, tenesmus, and malaise. For comparability, it is important to harmonize the primary clinical endpoint. An expert working group was convened on 2 February 2018 to review clinical data from Shigella CHIM studies performed to date and to develop a consensus primary endpoint. The consensus endpoint enabled "shigellosis" to present as severe diarrhea or moderate diarrhea or dysentery. The latter 2 criteria are met when concurrent with fever of 38.0°C and/or vomiting, and/or a constitutional/enteric symptom graded at least as "moderate" severity. The use of a blinded independent committee to adjudicate the primary endpoint by subject was also regarded as important. As safety of volunteers in challenge studies is of paramount importance and treatment timing can affect primary outcomes, a standard for early antibiotic administration was established as follows: (1) when the primary endpoint is met; (2) if a fever of ≥39.0°C develops; or (3) if the study physician deems it appropriate. Otherwise, antibiotics are given at 120 hours postinfectious challenge. The working group agreed on objective and subjective symptoms to be solicited, and standardized methods for assessing subject-reported severity of symptoms.

Epidemiology and associated microbiota changes in deployed military personnel at high risk of traveler's diarrhea

Travelers’ diarrhea (TD) is the most prevalent illness encountered by deployed military personnel and has a major impact on military operations, from reduced job performance to lost duty days. Frequently, the etiology of TD is unknown and, with underreporting of cases, it is difficult to accurately assess its impact. An increasing number of ailments include an altered or aberrant gut microbiome. To better understand the relationships between long-term deployments and TD, we studied military personnel during two nine-month deployment cycles in 2015–2016 to Honduras. To collect data on the prevalence of diarrhea and impact on duty, a total of 1173 personnel completed questionnaires at the end of their deployment. 56.7% reported reduced performance and 21.1% reported lost duty days. We conducted a passive surveillance study of all cases of diarrhea reporting to the medical unit with 152 total cases and a similar pattern of etiology. Enteroaggregative E. coli (EAEC, 52/152), enterotoxigenic E. coli (ETEC, 50/152), and enteropathogenic E. coli (EPEC, 35/152) were the most prevalent pathogens detected. An active longitudinal surveillance of 67 subjects also identified diarrheagenic E. coli as the primary etiology (7/16 EPEC, 7/16 EAEC, and 6/16 ETEC). Eleven subjects were recruited into a nested longitudinal substudy to examine gut microbiome changes associated with deployment. A 16S rRNA amplicon survey of fecal samples showed differentially abundant baseline taxa for subjects who contracted TD versus those who did not, as well as detection of taxa positively associated with self-reported gastrointestinal distress. Disrupted microbiota was also qualitatively observable for weeks preceding and following the incidents of TD. These findings illustrate the complex etiology of diarrhea amongst military personnel in deployed settings and its impacts on job performance. Potential factors of resistance or susceptibility can provide a foundation for future clinical trials to evaluate prevention and treatment strategies.

Diarrhea and associated illness characteristics and risk factors among British active duty service members at Askari Storm training exercise, Nanyuki, Kenya, January-June 2014

Travelers' diarrhea (TD) has historically been common among deployed military personnel and remains a leading infectious disease threat to this population. The risk factors, work performance, and illness associated with TD among British active duty service members exercising at British Army Training Unit Kenya (BATUK) were assessed. Members of the British Army who were finishing a 6-week combined arms training exercise in Nanyuki, Kenya, completed routine public health surveillance questionnaires. Survey data included information on demographics, rank, risk factors, illness characteristics, and impact on work performance. Among 1,227 survey respondents, 21.9% (n=269) reported having diarrhea, with an estimated 824 days of total missed work and 1,215 days of work underperformance. The majority of cases (54.6%) had multiple diarrheal episodes. One quarter (24.9%) of the respondents with TD sought medical care and 19.7% were bedded down because of their illness. There were no statistically significant differences between the TD and no TD groups on the demographic characteristics examined. The strongest risk factor for diarrhea was having a colleague with diarrhea (adjusted odds ratio=51.78; 95% confidence interval: 29.44-91.06). TD had a notable impact on duty status and operational capability. Efforts are needed to improve BATUK's participant education on the importance of diarrheal disease prevention and management.

Deployment Infectious Disease Threats: IDCRP Initiatives and Vision Forward

BACKGROUND

Infectious diseases pose a significant threat to health and readiness of military personnel deployed globally during wartime and peacekeeping activities. Surveillance and improvement in mitigation through research of infectious disease threats remain an integral part of Force Health Protection. Herein, we review research efforts of the Infectious Disease Clinical Research Program related to deployment and travel-related infections.

METHODS

The objectives of the Deployment and Travel-Related Infections Research Area are to (1) provide epidemiologic and clinical data, including pathogen-specific estimates of disease incidence among deployed troops, (2) execute clinical trials and effectiveness studies to improve recommendations regarding prevention and treatment of infections during deployment, and (3) evaluate the knowledge and practice patterns of health care providers engaged in deployment/travel medicine and the impact on outcomes. The centerpiece protocol of the research area is the Deployment and Travel-Related Infectious Disease Risk Assessment, Outcomes, and Prevention Strategies cohort study (TravMil), which was initiated in 2010 and collects data on a broad range of deployment-related infections.

RESULTS

To date, 4,154 deployed military personnel and traveling Department of Defense (DoD) beneficiaries have been enrolled in TravMil. Surveillance data collected through the TravMil study provide assessment of deployment and travel-related infectious disease threats, and the effectiveness of mitigation strategies. The incidence of travelers' diarrhea, influenza-like illness, and undifferentiated febrile illness is 20.48%, 9.34%, and 6.16%, respectively. The cohort study also provides necessary infrastructure to execute clinical trials. The TrEAT TD clinical trial evaluated the effectiveness of single-dose antibiotic therapy for travelers' diarrhea in the deployed setting. When compared to levofloxacin, azithromycin was not inferior; however, inferiority was not demonstrated with use of single dose of rifaximin. The trial findings supported the development of a deployment-related health guideline for the management of acute diarrheal disease. A clinical trial evaluating the effectiveness of rifaximin for prevention for travelers' diarrhea (Prevent TD) is underway.

CONCLUSIONS

The research area has proven its ability to conduct impactful research, including the development of field-expedient diagnostics, the largest DoD multi-site travelers' diarrhea randomized control trial in peacetime and combat settings, and informed Force Health Protection guidance. The research area continues to provide surveillance data to military commands via an established collaborative network of military treatment facilities, DoD laboratories (both within and outside the continental United States), foreign militaries, and academia. The conduct of clinical and translational research in a deployment setting presents significant challenges, most notably in recruitment/enrollment and compliance with study-related procedures during deployment.

Serum Biomarkers Identify Patients Who Will Develop Inflammatory Bowel Diseases Up to 5 Years Before Diagnosis

BACKGROUND & AIMS

Biomarkers are needed to identify patients at risk for development of inflammatory bowel diseases. We aimed to identify serum biomarkers of Crohn's disease and ulcerative colitis that can be detected and quantified before diagnosis.

METHODS

We obtained serum samples from patients archived before a diagnosis of Crohn's disease (n = 200) or ulcerative colitis (n = 199), as well as from 200 healthy individuals (controls), collected from 1998 through 2013 as part of the US Defense Medical Surveillance System. We measured levels of antibodies against microbes (anti-Saccharomyces cerevisiae IgA or IgG, anti-Escherichiacoli outer membrane porin C, anti-CBir1, anti-flagellin 2, anti-flagellin X, and perinuclear anti-neutrophil cytoplasmic antibodies) and 1129 proteins in each sample. We then used functional principal component analysis to derive the time-varying trajectory for each marker, which then was used in a multivariate model to predict disease status. Predictive performances at different prediagnosis timepoints were evaluated using area under the receiver operating characteristic curves (AUROCs). Biological pathways that were up-regulated in serum from patients with Crohn's disease were identified based on changes in protein abundance at different time periods preceding diagnosis.

RESULTS

We identified a panel of 51 protein biomarkers that were predictive of Crohn's disease within 5 years with an AUROC of 0.76 and a diagnosis within 1 year with an AUROC of 0.87. Based on the proteins included in the panel, imminent development of CD was associated with changes in the complement cascade, lysosomes, innate immune response, and glycosaminoglycan metabolism. Serum antibodies and proteins identified patients who received a diagnosis of ulcerative colitis within 5 years with an AUROC of only 0.56 and within 1 year with an AUROC of 0.72.

CONCLUSIONS

We identified a panel of serum antibodies and proteins that were predictive of patients who will receive a diagnosis of Crohn's disease within 5 years with high accuracy. By contrast we did not identify biomarkers associated with future diagnosis of ulcerative colitis.

Clinical outcomes in COVID-19 patients treated with tocilizumab: An individual patient data systematic review

Background

Current evidence suggests an important role of the interleukin‐6 (IL‐6) pathway in severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2)‐related cytokine release storm in severely ill coronavirus disease 2019 (COVID‐19) patients. Inhibition of the IL‐6 pathway with tocilizumab has been employed successfully in some of these patients but the data is mostly consistent of case reports and series.

Methods

We performed a systematic search of PubMed, Embase, and Medline from 22nd April 2020 and again on 27th April 2020 using the following search terms alone or in combination: “COVID‐19,” “coronavirus,” “SARS‐CoV‐2,” “COVID,” “anti‐interleukin‐6 receptor antibodies,” “anti‐IL‐6,” “tocilizumab,” “sarilumab,” “siltuximab.” We included studies that reported individual patient data. We extracted and analyzed individual level data on baseline characteristics, laboratory findings, and clinical outcomes. The primary endpoint was in‐hospital mortality. Secondary endpoints included in‐hospital complications, recovery rates, effect of patient characteristics on the primary outcome and changes in levels of inflammatory markers.

Results

Three hundred fifty‐two records were identified through a systematic search, of which 10 studies met the inclusion criteria. A single study currently under review was also added. Eleven observational studies encompassing 29 patients were included in the present review. There were more males (24 [82.8%]), and hypertension was the most common comorbidity (16 [48.3%]). Over an average of 5.4 hospital days, the primary endpoint occurred in 6 (20.7%) patients. Among surviving patients, about 10% had worsened disease and 17% recovered. The most common complication was acute respiratory distress syndrome (8 [27.6%]). The IL‐6 level was significantly higher after the initiation of tocilizumab with median (interquartile range) of 376.6 (148‐900.6) pg/mL compared to the baseline of 71.1 (31.9‐122.8) pg/mL (P = .002). Mean (standard deviation) levels of C‐reactive protein (CRP) were significantly decreased following treatment 24.6 (26.9) mg/L compared to baseline 140.4 (77) mg/L (P < .0001). Baseline demographics were not significantly different among survivors and nonsurvivors by Fisher's exact test.

Conclusion

In COVID‐19 patients treated with tocilizumab, IL‐6 levels are significantly elevated, which are supportive of cytokine storm. Following initiation of tocilizumab, there is elevation in the IL‐6 levels and CRP levels dramatically decrease, suggesting an improvement in this hyperinflammatory state. Ongoing randomized control trials will allow for further evaluation of this promising therapy.

Importance

Recent data indicate that severe COVID‐19 causes a cytokine release storm and is associated with worse clinical outcomes and IL‐6 plays an important role. It is suggestive that anti‐IL‐6 results in the improvement of this hyperinflammatory state. However, to our knowledge, there is no individual patient data systematic review performed to summarize baseline characteristics and clinical outcomes of COVID‐19 patients who received tocilizumab.

Interleukin‐6 (IL‐6) may play an important role in the pathogenesis of COVID‐19.

Data show that tocilizumab, an IL‐6 receptor antagonist, reduces COVID‐19 complications.

Our systematic review suggests that tocilizumab may improve survival in COVID‐19.

Genetic and Virulence Profiles of Enteroaggregative Escherichia coli (EAEC) Isolated From Deployed Military Personnel (DMP) With Travelers' Diarrhea

To discern if there was a particular genotype associated with clinical enteroaggregative Escherichia coli (EAEC) strains isolated from deployed military personnel (DMP) with travelers' diarrhea (TD), we characterized a collection of EAEC from DMP deployed to Afghanistan, Djibouti, Kenya, or Honduras. Although we did not identify a specific EAEC genotype associated with TD in DMP, we found that EAEC isolated at the first clinic visit were more likely to encode the dispersin gene aap than EAEC collected at follow-up visits. A majority of the EAEC isolates were typical EAEC that adhered to HEp-2 cells, formed biofilms, and harbored genes for aggregative adherence fimbriae (AAF), AggR, and serine protease autotransporters of Enterobacteriaceae (SPATEs). A separate subset of the EAEC had aggR and genes for SPATEs but encoded a gene highly homologous to that for CS22, a fimbriae more commonly found in enterotoxigenic E. coli. None of these CS22-encoding EAEC formed biofilms in vitro or adhered to HEp-2 cells. Whole genome sequence and single nucleotide polymorphism analyses demonstrated that most of the strains were genetically diverse, but that a few were closely related. Isolation of these related strains occurred within days to more than a year apart, a finding that suggests a persistent source and genomic stability. In an ampicillin-treated mouse model we found that an agg4A+ aar- isolate formed a biofilm in the intestine and caused reduced weight gain in mice, whereas a strain that did not form an in vivo biofilm caused no morbidity. Our diverse strain collection from DMP displays the heterogeneity of EAEC strains isolated from human patients, and our mouse model of infection indicated the genotype agg4A+ aar– and/or capacity to form biofilm in vivo may correlate to disease severity.

Deployment and Travel Medicine Knowledge, Attitudes, Practices, and Outcomes Study (KAPOS): Malaria Chemoprophylaxis Prescription Patterns in the Military Health System

The Deployment and Travel Medicine Knowledge, Attitudes, Practices, and Outcomes Study (KAPOS) examines the integrated relationship between provider and patient inputs and health outcomes associated with travel and deployments. This study describes malaria chemoprophylaxis prescribing patterns by medical providers within the U.S. Department of Defense’s Military Health System and its network of civilian healthcare providers during a 5-year period. Chemoprophylaxis varied by practice setting, beneficiary status, and providers’ travel medicine expertise. Whereas both civilian and military facilities prescribe an increasing proportion of atovaquone–proguanil, doxycycline remains the most prevalent antimalarial at military facility based practices. Civilian providers dispense higher rates of mefloquine than their military counterparts. Within military treatment facilities, travel medicine specialists vary their prescribing pattern based on service member versus beneficiary status of the patient, both in regards to primary prophylaxis, and use of presumptive anti-relapse therapy (PQ-PART). By contrast, nonspecialists appear to carry over practice patterns developed under force health protection (FHP) policy for service members, into the care of beneficiaries, particularly in high rates of prescribing doxycycline and PQ-PART compared with both military travel medicine specialists and civilian comparators. Force health protection policy plays an important role in standardizing and improving the quality of care for deployed service members, but this may not be the perfect solution outside of the deployment context. Solutions that broaden both utilization of decision support tools and travel medicine specialty care are necessary.

A grading system for local skin reactions developed for clinical trials of an intradermal and transcutaneous ETEC vaccine

BACKGROUND

Trials assessing the safety of novel vaccine candidates are essential in the evaluation and development of candidate vaccines. Immunogenicity and dose-sparing features of vaccination approaches which target skin and associated tissues have garnered increased interest; for enteric vaccines, cutaneous vaccination has been of particular interest. Cutaneous vaccine site reactions are among the most common and visible vaccine related adverse events (AEs) when skin routes are used. Regulatory guidelines governing classification of severity focus on functional impact but are insufficient to characterize a spectrum of skin reaction and allow for comparisons of routes, doses and products with similar local cutaneous AEs.

OBJECTIVES

Our group developed a grading scale to evaluate and compare cutaneous vaccine site reactions ahead of early-phase clinical trials of intradermal (ID) and transcutaneous immunization (TCI) with enterotoxigenic E.coli (ETEC) vaccine candidates (adhesin-based vaccine co-administered with LTR192G). We reviewed existing methods for characterizing the appearance and severity of local vaccine site reactions following TCI and ID vaccination and devised a standardized vaccine site appearance grading scale (VSAGS) for use in the clinical development of novel ETEC vaccine candidates which focused on pathophysiologic manifestation of skin findings.

RESULTS

Available data from published reports revealed erythematous papules and pruritus were the most common local AEs associated with TCI. Frequency of reactions varied notably across studies as did TCI vaccination methodologies and products. ID vaccination commonly results in erythema and induration at the vaccine site as well as pigmentation changes. There was no published methodology to characterize the spectrum of dermatologic findings.

CONCLUSION

ID and TCI vaccination are associated with a largely predictable range of cutaneous AEs. A grading scale focused on the appearance of cutaneous changes was useful in comparing cutaneous AEs. A standardized grading scale will facilitate documentation and comparison of cutaneous AEs.

Meeting Report: WHO Workshop on modelling global mortality and aetiology estimates of enteric pathogens in children under five. Cape Town, 28-29th November 2018

Investment in vaccine product development should be guided by up-to-date and transparent global burden of disease estimates, which are also fundamental to policy recommendation and vaccine introduction decisions. For low- and middle-income countries (LMICs), vaccine prioritization is primarily driven by the number of deaths caused by different pathogens. Enteric diseases are known to be a major cause of death in LMICs. The two main modelling groups providing mortality estimates for enteric diseases are the Institute for Health Metrics and Evaluation (IHME) at the University of Washington, Seattle and the Maternal Child Epidemiology Estimation (MCEE) group, led by Johns Hopkins Bloomberg School of Public Health. Whilst previous global diarrhoea mortality estimates for under five-year-olds from these two groups were closely aligned, more recent estimates for 2016 have diverged, particularly with respect to numbers of deaths attributable to different enteric pathogens. This has impacted prioritization and investment decisions for vaccines in the development pipeline.

The mission of the Product Development for Vaccines Advisory Committee (PDVAC) at the World Health Organisation (WHO) is to accelerate product development of vaccines and technologies that are urgently needed and ensure they are appropriately targeted for use in LMICs. At their 2018 meeting, PDVAC recommended the formation of an independent working group of subject matter experts to explore the reasons for the difference between the IHME and MCEE estimates, and to assess the respective strengths and limitations of the estimation approaches adopted, including a review of the data on which the estimates are based.

Here, we report on the proceedings and recommendations from a consultation with the working group of experts, the IHME and MCEE modelling groups, and other key stakeholders. We briefly review the methodological approaches of both groups and provide a series of proposals for investigating the drivers for the differences in enteric disease burden estimates.

Application of a cost-effectiveness analysis of pathogen-specific vaccines against gastroenteritis to a military population in a developing country setting

Vaccine implementation planning in low- and middle-income countries (LMIC) often focuses on children without considering special adult populations. We adapted an economic model developed by the United States Department of Defense (DoD) to evaluate the cost-effectiveness of vaccine acquisition strategies for Campylobacter-, ETEC-, Shigella-, and norovirus-associated gastroenteritis. We compared implementation costs with current medical management in the Peruvian armed forces, a special population of low- and middle-income (LMIC) adults with a high incidence of infectious gastroenteritis. Pathogen-specific vaccine implementation resulted in calculated cost-effectiveness ratio (CER) per duty day lost averted (CER_DDL) of $13,741; $1,272; $301; and $803, and a CER per diarrhea day averted of $2,130; $215; $51; and $199 for Campylobacter, ETEC, Shigella, and norovirus, respectively. These estimates compare favorably to CER_DDL estimates from high-income military population and suggest that implementing vaccines gastroenteritis may be cost-effective in the Peruvian military population.