Researchers are taking steps toward developing an live attenuated oral vaccine aimed at preventing invasive bacterial diarrhea caused by the Shigella bacteria.1
The Shigella bacteria can cause shigellosis—an intestinal infection characterized by diarrhea, fever and stomach cramps. It is one of four highly contagious bacteria that infects tens of millions of people around the world.2 Shigellosis spreads when fecal matter contaminates food, water, or surfaces. The bacteria can also be spready through sexual contact.
In the United States, Shigella causes an estimated 450,000 infections per year, and an estimated 38 to 40 deaths per year—a 0.008 to 0.009 percent death rate.2
A small phase two clinical trial has reported high-level protection in The Lancet Infectious Diseases. The protection is noted as being “higher than what has generally been reported for prior Shigella vaccine studies,” said study co-author Naine Rouphael, MD, professor of vaccinology and infectious diseases at Emory University.1
Two Study Participants Develop Severe Shigellosis Symptoms
The trial involved 108 healthy adults ages 18 to 49 who were randomly assigned to receive a live-attenuated oral vaccine targeting Shigella sonnei, or a placebo. The oral vaccine is known as WRS2 and contains a weakened live virus strain of the Shigella species. Two study participants who were given the vaccine developed symptoms of severe shigellosis and did not continue with the study.2
Epidemiologist Says Dosing May be Difficult Due to Bioindividuality
David Sack, MD, epidemiologist at John Hopkins Bloomberg School of Public Health, says that finding the right oral dose of the vaccine for the general population could prove to be difficult, as individuals could react to it differently.
The experimental vaccine has “highly encouraging results,” according to microbiologist Shangxin Yang, PhD. Dr. Yang notes that there is currently no approved vaccine for shigellosis, but the vaccine is far from being approved as the required large clinical trial would take three to six years to complete.1
Most treated cases of shigellosis are prescribed commonly used antibiotics. As with many other bacteria, Shigella is becoming increasingly resistant to antimicrobial drugs in large part due to the overprescription of antibiotics worldwide.3
Gates Foundation Funds Shigellosis Study
The World Health Organization (WHO) states that shigellosis is a leading bacterial cause of diarrhea worldwide, particularly in children under age five in developing countries. In March 2026, results from a Shigella study funded by the Bill and Melinda Gates Foundation were published in the Lancet Global Health. The author of the study, epidemiologist Patricia Pablinac, PhD, stated:
We have known Shigella is a major contributor to childhood diarrhea since the use of more sensitive diagnostic tools in the last decade. But until this study, we did not appreciate the incredibly high burden of antibiotic resistance in this bacteria, limiting treatment options and threatening global health.3
Unknown if Oral Vaccine will be Safe on Young Children
While the oral vaccine tested the dominant Shigella sonnei species found in the U.S., the dominant species worldwide is a different strain of Shigella known as Shigella flexneri. Yang states that because the vaccine was tested on adults and on the less common global bacterial strains, it is unclear whether the vaccine would be effective or safe in young children in low to middle income countries who bear the greatest burden of this illness.1
An additional intramuscular vaccine is in early stages of being developed and showing promise, according to Dr. Sack. He states these injectable vaccines could probably be safer.
Dr. Rouphael and her team plant to continue testing the oral vaccine and hope to test it in populations “that need it most, especially young children in places where Shigella is common.”1
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Click here to view References:1 Mehra S. An experimental oral vaccine may prevent invasive bacterial diarrhea. Science News July 21, 2026.
2 Dall C. Shigella vaccine shows promise in phase 2 trial. CIDRAP July 7, 2026.
3 Steelquist C. Drug-resistant Shigella threatens young children globally. UW Medicine Newroom Apr. 9, 2026.
2 Responses
Wonderful…another toxic vaccine pretending to be useful toward greater health.
Now we’ve graduated from the fallacy of public health, to global health. The health of the entire globe as mad scientists scurry around in little white lab coats pouring untold volumes of toxic chemicals down drains and waste untold volumes of human labor and non decomposable plastic resources on their ‘science’ experiments.
Here is an alternate pro tip to avoid ‘invasive bacterial diarrhea’. Don’t eat as much taco bell and stay away from all the legal and illegal migrants who’s cultural values of machismo and masculinity include not washing hands even after taking a two in the rest room. I swear the ladies have no idea how bad this is. Every single time we go anywhere with a high concentration of migrants I watch them stream endlessly right out of the urinals and toilets and but a scarce one or two of them may quick wash hands, most skip it entirely and don’t even bother with a paper towel either. They walk right back to the tables, touch all the public surface areas. Rather than asking for a vaccine to help with this we need to ask a much more pertinent question; When do the real deportations start? There is no fixing this. The cultural divides will never be bridged.