New vaccine could defeat a major cause of diarrheal disease : NPR

This summer, diarrhea made headlines in the United States with thousands of cases linked to Cyclospora from contaminated lettuce, resulting in the first two confirmed deaths in Michigan. Globally, diarrhea remains a persistent and deadly threat. Each year, over 1 million people succumb to diarrheal diseases like dysentery, with nearly half of the victims being children under five. Chad records the highest rate of childhood deaths, with approximately 1 in 140 children under five dying annually.

Despite its impact, diarrhea often receives inadequate attention in public health discussions due to the “poo taboo”—a reluctance to discuss the topic openly.

However, a new vaccine candidate brings hope.

“Rigorous” trial, “remarkable” response

The WRSs2 vaccine, developed by the Walter Reed Army Institute of Research, underwent trials at Cincinnati Children’s Hospital Medical Center and the Emory Vaccine Center’s Hope Clinic in Atlanta. This summer, The Lancet Infectious Diseases published the results, showing 89% efficacy against shigellosis, a leading cause of diarrheal deaths.

The study involved 108 adults, with half receiving the vaccine—a weakened form of the shigella bacteria in a liquid form, similar to yogurt. The dose, slightly less than a shot glass, was administered twice a month apart. The other half received salt water.

According to Dr. Robert Frenck, a professor of pediatrics at Cincinnati Children’s and co-leader of the trial, the weakened bacteria is designed to trigger an immune response without causing illness.

Dr. Kawsar Talaat, an infectious disease specialist at the Johns Hopkins Bloomberg School of Public Health, noted that despite the small number of participants, the trial’s rigorous design makes the 89% efficacy difficult to dismiss. In this trial, 81% of those in the placebo group fell ill, experiencing diarrhea and fever before receiving antibiotics.