Scientists Are Testing a Vaccine for Food Poisoning. It Can’t Come Soon Enough

Few things in this world are more miserable than food poisoning. You go out to eat some delicious foods, or cook at home. You’re happy, full, and then… everything goes south. Sometimes literally.

But hark! This torturous fate may soon be vanquished, thanks to some scientists at the University of Maryland who might just have created a vaccine that protects against Salmonella bacteria, one of the most common sources of foodborne illness and potentially life-threatening infections.

So far, the researchers have tested out their vaccine in human volunteers in a Phase I clinical trial. Not only did the vaccine appear to be safe and well-tolerated, it also seemed to create a robust immune response to the target bacteria.

“These findings provide a strong foundation for future studies,” study co-author Myron Levine, professor emeritus at UM’s School of Medicine, said in a statement. The results were published Wednesday in Nature Medicine.

A pervasive threat

When people get Salmonella, it’s typically caused by a specific species of the bacteria, called Salmonella enterica. But there are many subtypes, or serovars, of Salmonella within this species. One notorious subtype (Salmonella Typhi) causes typhoid fever—an extreme form of food poisoning that causes a high fever (hence the name), a cough, rash, nausea, weakness, and diarrhea, and which can last as long as a month and require special antibiotics to treat. Other, non-typhoidal subtypes cause more typical food poisoning symptoms, including vomiting, diarrhea, and stomach pain.

The most common sources of Salmonella are undercooked meat, poultry, eggs, or unwashed fruit and vegetables, as well as through contact with infected people. Typhoid spreads similarly, and through water contaminated with the urine or feces of an infected person.

More than a million Americans are sickened by Salmonella every year, and tens of thousands are hospitalized as a result. Most Salmonella infections don’t last long—just a few days or a week—but they can sometimes lead to severe, even fatal illness. These severe cases tend to happen when the bacteria spreads beyond the digestive tract and invades other parts of the body. They’re also more likely to occur in children under five, the elderly, or people with weakened immune systems.

The team’s vaccine targets three different subtypes of Salmonella: the bacteria that cause typhoid fever and two other subtypes that are a common source of invasive infections in young children, especially in less developed areas of the world.

The team’s vaccine is a conjugate vaccine, meaning it combines polysaccharide antigens (sugar molecules, to put it plainly) from the outer coating of these bacteria with a carrier protein that boosts the immune system’s ability to recognize the bacteria. The vaccine is currently code-named the trivalent Salmonella conjugate vaccine, or TSCV.

Early promise

The researchers tested TSCV in a small, controlled trial involving 22 healthy adult volunteers from the U.S. Two groups received varying doses of the vaccine, while the third was given a placebo.

Phase I trials are primarily meant to vet a drug or vaccine’s safety, and TSCV passed with flying colors. The vaccine was found to be safe, with the most common adverse event being pain at the injection site. Importantly, the researchers also detected a immune response to the three subtypes in all the vaccinated volunteers, including the production of antibodies, suggesting that TSCV works as intended.

Importantly, the findings are based on a small sample size. There is still plenty more work needed to affirm the vaccine’s broader safety and effectiveness. But if it keeps hitting its milestones, then TSCV could be a boon to the world, and especially for the people most vulnerable to severe Salmonella infections.

“These results are highly encouraging,” lead researcher Wilbur Chen, a professor of medicine at UM, said in a statement. “They show that TSCV has the potential to protect children in regions where both typhoid and Salmonella are endemic and deadly.”

TSCV’s potential benefits could extend even beyond that. The subtypes it targets don’t just cause invasive infections, the researchers note, they’re also some of the most common strains of Salmonella that cause food poisoning in the U.S.

Still, it is always important to practice good food safety and proper hygiene no matter what (wash your hands and don’t undercook your chicken, people), but it’d be incredible to know that in the future, when you are chowing down, Salmonella could be one less thing to worry about.