Researchers at North Carolina State University have shown that vaccine applied to dental floss and used to clean the junctional epithelium, the permeable tissue at the base of the gum pocket, can stimulate antibody production in both the bloodstream and mucosal surfaces such as the nose and lungs. The study, published in Nature Biomedical Engineering, tested the method in mice using a flu vaccine and compared it to sublingual and nasal delivery routes.

The junctional epithelium is more permeable than most epithelial tissues and lacks the barrier properties that block efficient vaccine uptake through nasal or oral mucosa. This makes it a practical entry point for mucosal immunisation without the safety concerns associated with intranasal delivery, which carries a risk of vaccine reaching the brain. Antibody responses via floss-based delivery were superior to sublingual vaccination and comparable to nasal vaccination.

The technique worked with peptide, protein, inactivated virus, and mRNA vaccine formats. A small human pilot study using fluorescent dye on floss picks found that around 60% of the applied substance reached the gum pocket, supporting feasibility for human use. The researchers note the approach would not be suitable for infants without teeth, and its performance in patients with periodontal disease remains unknown. Clinical trials have not yet begun.