Flossing teeth every day has long become standard for many people’s oral care. But can you imagine? This humble daily item may soon become a “new artifact” for vaccination.
Recently, a study published in the journal Nature Biomedical Engineering confirmed that dental floss coated with vaccine components can deliver vaccines through the gingival sulcus, triggering strong systemic and mucosal immune responses in mice, even providing 100% protection against lethal influenza viruses. This needle-free, painless vaccination method not only makes getting vaccinated as simple as brushing teeth but also offers new possibilities for rapid immunization during pandemics.
Why Dental Floss?
The secret lies in the “junctional epithelium” (JE) deep in the gingival sulcus. This specialized tissue at the junction of the gums and teeth is inherently “highly permeable”—it has larger intercellular spaces and looser junctional structures, acting like a “natural small gate” that allows foreign substances to easily enter the body. What’s more, the area beneath the junctional epithelium is filled with immune cells such as neutrophils and dendritic cells, making it a “gathering place for immune cells.” Once these cells recognize antigens in the vaccine, they can quickly initiate immune responses.
The research team capitalized on this feature. They chose flat ribbon floss (instead of braided floss) as the carrier because its smooth surface can uniformly adsorb vaccine components, avoiding the “trapping and waste” between the fibers of braided floss. Experiments showed that the floss coating adheres stably: even after mice chewed and drank water, vaccine components remained in the gingival sulcus for up to 72 hours, whereas vaccines applied directly via drops disappeared within 24 hours—meaning the floss enables sustained and efficient vaccine delivery.
“Flossing” for Mice
In mouse experiments, the research team tested various vaccine types, with encouraging results:
- Influenza vaccine: After three vaccinations using floss coated with inactivated influenza virus, all mice survived exposure to a lethal dose of the influenza virus, while all unvaccinated mice died. Crucially, antibodies were detected in the mice’s blood, feces, saliva, and even bone marrow. Antibody-secreting cells in the bone marrow indicated the formation of immune memory, which can provide long-term protection.
- Universal influenza vaccine: A nanoparticle vaccine designed targeting the highly conserved M2e protein, when delivered via dental floss, provided 100% protection against two different influenza subtypes (H1N1 and H3N2) in mice, regardless of whether they ate or drank immediately afterward. Its protective effect was comparable to nasal vaccination but with better safety (avoiding potential neurological side effects of nasal vaccination).
- mRNA vaccine: Floss coated with GFP-mRNA successfully expressed proteins in mouse gingival tissues and induced serum antibody production, demonstrating that floss is also suitable for emerging vaccine platforms like mRNA.
Subsequently, in tests with human volunteers, 27 healthy adults used floss sticks coated with fluorescent dye. The average delivery efficiency of the dye in the gingival sulcus reached 59%, and even with only 2 uses, the delivery rate reached 48.5%. More pleasantly, 93% of volunteers reported no pain during use, 78% found the operation “extremely simple,” and 93% preferred floss-based vaccination over traditional injections.
Three Key Advantages of Floss Vaccines
Compared to traditional injections or other mucosal vaccination methods, floss vaccines offer advantages that can be described as “dimension-reducing strikes”:
- Needle-free and painless, boosting vaccination willingness: No needles are needed, avoiding pain and needle phobia, making it especially suitable for children and people resistant to injections.
- No cold chain required, facilitating distribution: The floss-coated vaccine can be stored dry without the need for cold-chain transportation; it can even be delivered by mail, which is highly advantageous in resource-poor areas or during pandemics.
- Dual mucosal and systemic immunity: It can activate antibodies in the blood while forming immune barriers in mucosal sites such as the respiratory and digestive tracts, making it more effective against pathogens like influenza and COVID-19 that invade through mucous membranes.
Professor Harvinder Singh Gill, the study’s lead researcher, stated: “In the future, people may get vaccinated using dental floss while brushing their teeth, as easily as part of their daily care.”
Summary
Although floss vaccines are still in the experimental stage, their potential is already evident. The research team notes that this method may future be used for: preventing respiratory infectious diseases (such as influenza and COVID-19); combating sexually transmitted diseases (by inducing vaginal mucosal immunity); and even as a delivery tool for cancer vaccines.
Of course, it has limitations—it must be used in people with teeth and cannot be administered to infants. But for the vast majority of the population, this “daily” vaccination method may completely transform the landscape of public health protection.
Perhaps in the near future, your floss box will contain not only floss for cleaning plaque but also “vaccine floss” that prevents influenza. Brushing teeth, flossing, and getting vaccinated—all in one step. Health protection has never been so simple.
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Reference
Ingrole, Rohan SJ, et al. “Floss-based vaccination targets the gingival sulcus for mucosal and systemic immunization.” Nature Biomedical Engineering (2025): 1-20.