A new experimental oral vaccine has shown strong protection against Shigella, a major bacterial cause of severe diarrhoea and dysentery. The result matters because no licensed Shigella vaccine exists, despite the disease posing a serious risk to young children in lower-income countries and becoming harder to treat as antibiotic resistance grows.

In a phase 2, double-blind US trial, the live-attenuated vaccine candidate WRSs2 was tested in healthy adults aged 18 to 49 using a controlled infection model. It reportedly provided 89% protection against Shigella sonnei infection; however, further studies will be needed to establish its safety and effectiveness in the children and settings most affected by the disease.