The vaccine, known as ETVAX, is designed to protect against enterotoxigenic Escherichia coli (ETEC), a major bacterial cause of diarrhoea in young children and the most common cause of travellers’ diarrhoea globally. ETEC infections contribute significantly to childhood illness in countries such as Nigeria, where recurrent diarrhoeal episodes remain a public health concern.
Strong Efficacy in Young Children
The phase IIb study, funded by the European & Developing Countries Clinical Trials Partnership, evaluated the safety and effectiveness of ETVAX in 4,936 children aged between six and 18 months across multiple regions of The Gambia.
In the randomised, double-blind, placebo-controlled trial, participants received a three-dose regimen of either ETVAX or a placebo and were monitored for up to 24 months.
Findings from the study demonstrated:
- Approximately 50% reduction in ETEC-positive moderate-to-severe diarrhoea, regardless of co-infections.
- 81% vaccine efficacy against ETEC-positive moderate-to-severe diarrhoea when enteroparasitic co-infections were excluded.
- 68% efficacy among children vaccinated before nine months of age, underscoring the importance of early immunisation.
- A 21% reduction in all-cause moderate-to-severe diarrhoea over the two-year follow-up period.
Researchers say the results indicate that ETVAX not only reduces disease severity but could also significantly lower the overall burden of diarrhoeal illness in early childhood.
Addressing a Major Cause of Childhood Illness
ETVAX is currently the most advanced ETEC vaccine candidate in clinical development. It is formulated to provide coverage against more than 90% of circulating ETEC strains in high-burden settings — a critical feature given the diversity of bacterial strains responsible for infection.
Debora Bade of the EDCTP Association described the findings as a major milestone.
“We are proud to see this project reach such an important milestone. These results provide a critical foundation for advancing into a phase III study and, if successful, will bring us closer to delivering a much-needed new vaccine to prevent diarrhoeal disease,” she said in a statement.
Pathway to Phase III and Wider Impact
With the successful completion of phase IIb trials, ETVAX is now considered phase III-ready for the prevention of moderate-to-severe ETEC diarrhoea in infants and young children in low- and middle-income countries.
If larger phase III trials confirm the vaccine’s safety and efficacy — and regulatory approval is secured — ETVAX could become a vital new tool in reducing ETEC-related diarrhoea in high-burden regions.
Beyond immediate illness prevention, experts note that reducing repeated diarrhoeal episodes in early childhood may help avert long-term developmental setbacks associated with malnutrition and impaired growth.
As global health stakeholders intensify efforts to curb preventable childhood diseases, the progress of ETVAX signals renewed optimism in the fight against one of the world’s most persistent and deadly childhood infections.