The National Institutes of Health (NIH) has indicated that vaccines administered through dental floss could represent a “promising” alternative to traditional injectable methods. The NIH noted that while most vaccines are delivered via needles, there is growing interest in needle-free options. An NIH-funded study suggests that dental floss might offer a practical and viable substitute for injectable vaccines, though further research is required to confirm its effectiveness.

Previous investigations have explored the mouth as a potential site for vaccine delivery, as it can stimulate immunity in both the bloodstream and mucosal tissues—areas where viruses often enter. However, prior attempts to administer vaccines via the cheeks or under the tongue have yielded inconsistent results.

In a recent study led by Dr. Harvinder Singh Gill at North Carolina State University, researchers tested the feasibility of delivering vaccines through the gums. They focused on the gingival sulcus, the small space between teeth and gums, which features a permeable tissue called the junctional epithelium. This property made it a candidate for vaccine delivery using dental floss. The findings were published in Nature Biomedical Engineering on July 22, 2025.

The team coated flat tape dental floss with various vaccine components, including peptides, proteins, and inactivated influenza viruses, and used it to floss mice teeth in the lab. The compounds successfully transferred into gum tissue, with floss coated in the influenza virus triggering immune responses and antibody production in the animals. Immune activity was observed across multiple organs, along with antibodies in both the bloodstream and mucosal surfaces.

The researchers then tested whether the floss-based vaccine could protect mice from fatal influenza infection. The results showed full protection, outperforming under-the-tongue vaccines and matching nasal delivery in effectiveness.

Rohan Ingrole, a study author, highlighted that applying vaccines through the junctional epithelium generated stronger mucosal antibody responses than current oral vaccination methods. He also noted that the floss technique provided comparable flu protection to nasal vaccines. Gill described the approach as “extremely promising,” emphasizing its potential to overcome barriers in nasal vaccine delivery.

The study’s abstract detailed how floss-based vaccination effectively delivered diverse vaccine types, including proteins, inactivated viruses, and messenger RNA. In mice, this method stimulated robust immune responses and durable protection against influenza. Human trials using fluorescent dye also demonstrated the feasibility of reaching the gingival sulcus via floss. The findings position floss-based vaccination as a simple, needle-free strategy with enhanced immune activation compared to existing mucosal methods.