Developing new vaccines against diarrheal disease

Diarrhea is the second leading cause of death in children under the age of five. Each year, approximately 1.6 million children worldwide die from severe, dehydrating diarrhea, and millions more are hospitalized, most of whom are in developing countries. The leading bacterial causes of diarrhea are enterotoxigenic Escherichia coli (ETEC) and Shigella, which, combined, are responsible for nearly one million of these young deaths each year. In addition, many more children suffer from diarrheal disease-associated malnutrition and its adverse consequences on physical and cognitive development.

ETEC may be the first enteric illness encountered by many infants, and Shigella is one of the most frequent causes for hospitalization of infants and young children experiencing severe diarrhea in low-resource settings. Access to appropriate medical care for diarrhea and dehydration is limited in developing countries, and Shigella is becoming increasingly more resistant to the antibiotics most commonly used for treatment. Therefore, prevention through vaccination is a critical part of the strategy to reduce the incidence and severity of diarrheal disease.

PATH’s Enteric Vaccine Initiative is collaborating with public- and private-sector partners to advance the development of safe, effective, and affordable vaccines against Shigella and ETEC. PATH is identifying and prioritizing vaccine candidates and moving the most promising ones through rigorous preclinical and clinical studies in an effort to make these vaccines available in the world’s poorest countries as quickly as possible.

PATH’s target product profile is focused on vaccines for infants and children that are designed to be practical for low-resource countries. For this reason, PATH is optimizing vaccine stabilization and developing formulations that will be easily administered to infants in a developing-country setting. A combination ETEC and Shigella vaccine is also being pursued because of its potential to offer broader coverage against diarrhea-causing pathogens.

PATH also implements two projects focused on vaccines for rotavirus, another important and deadly diarrheal disease. One is helping developing countries access and afford two currently licensed rotavirus vaccines, while the other is working with emerging manufacturers in China and India to develop new rotavirus vaccines.

In addition, PATH wants to increase the level of disease awareness and prioritization for vaccines like these and is pursuing an advocacy and policy strategy that integrates information about enteric diseases within the broader public health priority of diarrheal disease control. This framework connects the problem of diarrheal disease with solutions that include new and forthcoming preventive vaccines as well as new and existing treatment interventions.

Through these projects and work to promote breastfeeding, child nutrition, and clean water systems, PATH is pursuing a comprehensive strategy to combat diarrheal disease burden in low-resource countries.