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HOW DENTAL FLOSS COULD ONE DAY DELIVER VACCINES
Fear of needles is common, and it’s often a reason people avoid getting vaccinated or immunized. NC State University researchers contributed to a recent study finding that dental floss could be an effective way to administer vaccines and immunizations instead of shots.
Afraid of needles? If so, you’re not alone.
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In 2018, a meta-analysis of nearly 120 research articles estimated that, while needle fear generally lessens as we get older, up to 30% of the population still fears needles as young adults. The same study found that more than 15% of adults who don’t get their flu shot avoid it because they’re scared of needles.
Patients who fear needles might one day have another way to get a vaccine, though. In a recently published paper, researchers demonstrated a novel vaccine delivery method in an animal model — using dental floss.
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History of Syringes
The disposable syringe as we know it dates back to the mid-20th century, when inventors discovered how to combine hypodermic needles with syringes made of plastic. The syringe itself — a simple pump made of a plunger fit tightly inside a tube — has been around for thousands of years, though.
Many questions still need to be answered before the novel floss technique can be considered for clinical use, but the researchers see several potential advantages over other vaccine delivery methods.
“For example, it would be easy to administer, and it addresses concerns many people have about being vaccinated with needles,” says Harvinder Singh Gill, the Ronald B. and Cynthia J. McNeill Term Professor in Nanomedicine at NC State University, who’s a corresponding author of the paper on the work. “And we think this technique should be comparable in price to other vaccine delivery techniques.”
What’s more, by introducing a vaccine via the tissue between the teeth and gums, their testing showed it’s possible to stimulate antibody production in places of the body where it can make the most difference.
“Mucosal surfaces are important because they are a source of entry for pathogens, such as influenza,” Gill says. “However, if a vaccine is given by injection, antibodies are primarily produced in the bloodstream throughout the body, and relatively few antibodies are produced on mucosal surfaces.”
When a vaccine is delivered via a mucosal surface — such as the lining of the nose and lungs — Gill says that antibodies are stimulated both in the bloodstream and on the mucosal surfaces themselves.
“This improves the body’s ability to prevent infection, because there is an additional line of antibody defense before a pathogen enters the body,” Gill explains.
Illustration of vaccine-coated floss being delivered via the junctional epithelium.
Credit: Jie Sun, NC State University.
How it Works
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In the deepest part of the pockets between your teeth and gums, you’ll find a thin layer of tissue known as the junctional epithelium. Unlike other epithelial tissues, the junctional epithelium lacks a barrier — which allows it to release bacteria-fighting immune cells.
“Because the junctional epithelium is more permeable than other epithelial tissues — and is a mucosal layer — it presents a unique opportunity for introducing vaccines to the body in a way that will stimulate enhanced antibody production across the body’s mucosal layers,” Gill says.
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Not the Average Epithelium
The term epithelium applies to the tissue lining the surface of your lungs, gut and more. Most epithelial tissues include robust barriers designed to keep bad things from entering your bloodstream. But the junctional
epithelium is different.
The researchers applied a peptide flu vaccine to unwaxed dental floss and then flossed the teeth of lab mice to determine the viability of their novel delivery method. They compared the resulting antibody production in mice that received the vaccine through flossing the junctional epithelium with mice that received the vaccine via the nasal epithelium or mucosal tissue under the tongue.
“We found that applying vaccine via the junctional epithelium produces far superior antibody response on mucosal surfaces than the current gold standard for vaccinating via the oral cavity, which involves placing vaccine under the tongue,” says Rohan Ingrole, first author of the paper, who was a Ph.D. student under Gill at Texas Tech University. “The flossing technique also provides comparable protection against flu virus as compared to the vaccine being given via the nasal epithelium.”
The researchers also tested whether the junctional epithelium delivery method worked for three other prominent classes of vaccines: proteins, inactivated viruses and mRNA. In all three cases, the epithelial junction delivery technique produced robust antibody responses in the bloodstream and across mucosal surfaces.
Limitations and Next Steps
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While regular floss worked as an adequate vaccine delivery method for lab mice, the researchers were aware that it’s much less practical to ask people to hold vaccine-coated floss in their fingers.
To address that challenge, the researchers investigated whether floss picks would be a suitable alternative. They coated floss picks with fluorescent food dye and then recruited close to 30 study participants. After explaining the concept of delivering vaccines via floss, they asked the participants to try to deposit the food dye in their epithelial junctions.
“We found that approximately 60% of the dye was deposited in the gum pocket, which suggests that floss picks may be a practical vaccine delivery method to the epithelial junction,” Ingrole says.
By coating floss picks with fluorescent dye, the researchers showed that floss picks could be a practical way to deliver vaccines via the epithelial junction.
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Gill says that they’re optimistic about their preliminary results and, depending on their future findings, may attempt to move toward clinical trials.
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For all the potential advantages the flossing technique could offer, however, it does also come with some drawbacks. Namely, it wouldn’t work for infants and toddlers who don’t have teeth yet. Additionally, Gill says that further research would be needed to determine whether the approach might work for people with gum disease or other oral infections.
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The research paper, “Floss-based vaccination targets the gingival sulcus for mucosal and systemic immunization,” is published in the journal Nature Biomedical Engineering. Co-authors of the paper include Akhilesh Kumar Shakya, Chang Hyun Lee and Lazar Nesovic of Texas Tech; Gaurav Joshi of Texas Tech and NC State; and Richard Compans of Emory University.
Editor's note: This article was adapted from " How Dental Floss Could One Day Deliver Vaccines" which originally appeared at https://news.ncsu.edu/2025/08/how-dental-floss-could-one-day-deliver-vaccines/