Scientists use dental floss to deliver vaccines without needles
Flossing your teeth at least once a day is an essential part of any oral health routine. But it might also one day protect other parts of the body as scientists have created a novel, needle-free vaccine approach using a specialized type of floss.In a study published in Nature Biomedical Engineering, researchers demonstrated that when floss laced with vaccine components, such as proteins and inactive viruses, was applied along the gum lines of mice, it triggered an immune response.This method of vaccine delivery is effective because the areas of gum between the teeth are highly permeable, allowing them to absorb vaccine molecules easily.Flossing miceIn the experiment, researchers flossed 50 mice every two weeks for 28 days, which wasn’t an easy task. To floss each mouse, one person had to gently pull their jaw down with the metal ring from a keychain while another did the flossing.Four weeks after the final vaccine dose, the mice were exposed to a lethal strain of flu. All rodents that received the floss-based vaccine survived while the unvaccinated animals died. Additionally, the mice that had been flossed had a more widespread immune response throughout their bodies. Flu antibodies were detected in their feces, saliva and even in their bone marrow.Floss coated with rhodamine-tagged Ova for flossing mice incisors ex vivo. Credit: Nature Biomedical Engineering (2025). DOI: 10.1038/s41551-025-01451-3 Finding antibodies in the bone marrow suggests the mice’s bodies had established a long-term immune response. The researchers also saw an increase in T Cells (a type of immune cell that fights off infections) in the mice‘s lungs and spleen.Next, the researchers wanted to see whether flossing would be a viable approach for humans. So they asked 27 healthy volunteers to floss with dental picks coated with food dye. On average, the dye reached the gums about 60% of the time.Overcoming hurdlesThe mouth and nose are the primary entry points for many viruses, making the oral cavity an ideal site for vaccine delivery. However, scientists have faced significant hurdles in developing needle-free vaccine alternatives for these areas due to the body’s tough defenses against foreign invaders. A floss-based approach could bypass these challenges, offering a promising new method.Demonstration of flossing mice incisors, ex vivo, with rhodamine-tagged Ova. Credit: Nature Biomedical Engineering (2025). DOI: 10.1038/s41551-025-01451-3These findings establish floss-based vaccination as a simple, needle-free strategy that enhances vaccine delivery and immune activation compared with existing mucosal immunization methods,” wrote the researchers.This innovative approach to vaccine delivery offers a number of other benefits. One of the most compelling is that it could improve vaccine uptake, especially among those with a fear of needles. Additionally, floss-based vaccines wouldn’t require special transport and storage in cold temperatures. They could be easily delivered by mail, which would be useful for rapid mass vaccination during pandemics.
