travellers' diarrhoea vaccine patch

The travellers' diarrhoea vaccine patch is a transcutaneous immunization (TCI) system developed to prevent moderate-to-severe diarrhoea caused by enterotoxigenic *Escherichia coli* (ETEC). The system utilizes a patch containing 37.5 μg of heat-labile toxin (LT) from ETEC as the active antigen. Delivery is achieved by first preparing the skin with a small abrasive device to disrupt the stratum corneum, followed by the application of the patch to the upper arm. The mechanism of action involves the LT antigen being taken up by Langerhans cells in the epidermis, which then migrate to regional lymph nodes to stimulate a mucosal and systemic immune response. Originally developed by Iomai Corporation (later acquired by Intercell, now Valneva), the vaccine reached Phase 3 clinical trials. However, a large field trial conducted in travellers from Europe to Mexico and Guatemala failed to demonstrate statistically significant protective efficacy against ETEC-associated diarrhoea, leading to the discontinuation of its development.

Other names

LT patchETEC vaccine patchtranscutaneous LT vaccineheat-labile toxin patch