Oral Shigella Vaccine Shows 89% Efficacy In Human Challenge Trial
An oral Shigella vaccine developed at the Walter Reed Army Institute of Research showed 89% efficacy in a human challenge trial, offering a potential new tool against deadly diarrheal disease.[1]
The randomized study enrolled 108 adult volunteers at Cincinnati Children's Hospital and Emory's Hope Clinic; half received the WRSs2 vaccine and half a placebo.[1] After deliberate exposure to Shigella, 81% of placebo recipients developed shigellosis while nearly 90% of vaccinated participants were protected.[1] The results were published in The Lancet Infectious Diseases and were reported by NPR on August 7, 2026.[1]
WRSs2 was developed at the Walter Reed Army Institute of Research as an oral candidate meant to prevent Shigella infections.[1] Shigella causes severe diarrhea and is a leading cause of death among young children in low-resource settings, which is why an effective vaccine is considered a global health priority.[1]
Researchers say larger field trials and testing in children and in places where Shigella is common will be needed before the vaccine could be deployed widely.[1]
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📌 Key Facts
- The WRSs2 vaccine, developed at Walter Reed Army Institute of Research, was reported 89% effective against shigellosis.
- The randomized trial enrolled 108 adult volunteers at Cincinnati Children's and Emory's Hope Clinic, with half receiving vaccine and half placebo.
- After deliberate exposure, 81% of placebo recipients developed illness, while nearly 90% of vaccinated participants were protected.
- Results were published in The Lancet Infectious Diseases in summer 2026 and reported by NPR on August 7, 2026.
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