Experimental Shigella Vaccine Shows 89% Efficacy in Adult Trial, Offering Hope Against Deadly Diarrhea

An experimental vaccine named WRSs2, created by the Walter Reed Army Institute of Research, underwent a randomized trial with 108 adult volunteers at Cincinnati Children’s Hospital Medical Center and Emory Vaccine Center’s Hope Clinic. Administered in two oral doses of a weakened Shigella sonnei strain, the vaccine prevented infection in 89% of recipients, whereas 81% of the placebo group developed diarrhea and fever. Participants experienced mild adverse events, including headaches and transient diarrhea, but no serious illnesses required hospitalization.

Shigellosis remains a leading cause of fatal diarrheal illness, particularly among children under five in regions with poor sanitation, and rising antibiotic resistance hampers treatment. Experts praised the trial’s results but called for larger studies focused on young children in high-risk areas. The ultimate aim is a broader vaccine that could also target other bacterial diarrheal pathogens.