Vaccine value profile for Shigella

Shigella is the leading bacterial cause of diarrhoea and the second leading cause of diarrhoeal mortality among all ages. It also exhibits increasing levels of antibiotic resistance. The greatest burden is among children under five in low- and middle-income countries (LMICs). As such, a priority strategic goal of the World Health Organization (WHO) is the development of a safe, effective and affordable vaccine to reduce morbidity and mortality from Shigella-attributable dysentery and diarrhea, including long term outcomes associated with chronic inflammation and growth faltering, in children under 5 years of age in LMICs. In addition, a safe and effective Shigella vaccine is of potential interest to travellers and military both to prevent acute disease and rarer, long-term sequelae. An effective Shigella vaccine is also anticipated to reduce antibiotic use and thereby help diminish further emergence of enteric pathogens resistant to antimicrobials. The most advanced vaccine candidates are multivalent, parenteral formulations in Phase 2 and Phase 3 clinical studies. They rely on O-antigen-polysaccharide protein conjugate technologies or, alternatively, outer membrane vesicles expressing penta-acylated lipopolysaccharide that has been detoxified. Other parenteral and oral formulations, many delivering a broader array of Shigella antigens, are at earlier stages of clinical development. These formulations are being assessed in alignment with the WHO Preferred Product Characteristics, which call for a 1 to 2 dose primary immunization series given during the first 12 months of life, ideally starting at 6 months of age. This 'Vaccine Value Profile' (VVP) for Shigella is intended to provide a high-level, holistic assessment of the information and data that are currently available to inform the potential public health, economic and societal value of pipeline vaccines and vaccine-like products. This VVP was developed by a working group of subject matter experts from academia, non-profit organizations, government agencies and multi-lateral organizations. All contributors have extensive expertise on various elements of the Shigella VVP and collectively aimed to identify current research and knowledge gaps. The VVP was developed using only existing and publicly available information.

A site assessment tool for inpatient controlled human infection models for enteric disease pathogens

The use of the controlled human infection model to facilitate product development and to advance understanding of host-pathogen interactions is of increasing interest. While administering a virulent (or infective) organism to a susceptible host necessitates an ongoing evaluation of safety and ethical considerations, a central theme in conducting these studies in a safe and ethical manner that yields actionable data is their conduct in facilities well-suited to address their unique attributes. To that end, we have developed a framework for evaluating potential sites in which to conduct inpatient enteric controlled human infection model to ensure consistency and increase the likelihood of success.

Site-specific interventions to improve prevention of mother-to-child transmission of human immunodeficiency virus programs in less developed settings

This article reviews the experiences of programs designed to provide access to prevention of mother-to-child transmission services with the goal of improving services in resource-constrained settings. The article reports new data from the Elizabeth Glaser Pediatric AIDS Foundation's prevention of mother-to-child transmission program in sub-Saharan Africa, which has provided human immunodeficiency virus testing to more than 1,300,000 pregnant women and antiretroviral prophylaxis to 134,000 human immunodeficiency virus-infected pregnant women and more than 78,000 human immunodeficiency virus-exposed infants. Review of qualitative program data highlights the practical innovations that sites are implementing to improve the uptake of prevention of mother-to-child transmission services. Recommendations discussed include opt-out counseling and testing, rapid human immunodeficiency virus testing in antenatal care, counseling and testing in maternity, and provision of antiretroviral prophylaxis for mother and infant at the time of human immunodeficiency virus testing. Successful programmatic innovations need to be disseminated widely as more aggressive prevention strategies must be implemented to increase access to more than 10% of pregnant women worldwide.