Dental Floss Could Deliver Vaccines Without Needle

In a breakthrough that blends everyday hygiene with cutting-edge immunology, researchers at North Carolina State University have developed a novel method for vaccine delivery—through dental floss. The technique utilizes unwaxed dental floss coated with vaccine material, which is gently threaded between the teeth and gums. It targets the junctional epithelium, a thin, porous tissue at the gumline that connects oral surfaces to the immune system. This unique interface is highly permeable and teeming with immune cells, offering an ideal site for triggering protective responses without piercing the skin.

In lab experiments, mice that received a flu vaccine via floss showed robust mucosal immunity, particularly in surfaces like the nose and lungs—critical areas where respiratory viruses first enter the body. Compared to sublingual (under the tongue) methods, flossing generated stronger immune reactions and was nearly as effective as nasal sprays. The mucosal response is important not just for preventing illness, but for reducing transmission within communities.

Importantly, the floss method worked across a variety of vaccine types, including proteins, inactivated viruses, and mRNA, signaling potential compatibility with COVID-19 and other future threats. It sidesteps some risks associated with nasal delivery, such as inadvertent access to brain tissues, and offers a highly localized, targeted approach.

This innovation paves the way for at-home vaccine administration, particularly appealing for those who are needle-averse or lack access to traditional healthcare infrastructure. Unlike injections, the floss doesn’t require refrigeration (depending on the formulation), trained personnel, or specialized equipment.

The junctional epithelium’s strategic position between the gum and tooth makes it a gateway to the lymphatic system. It naturally releases immune cells and provides a direct line of communication between oral surfaces and systemic defenses. Until now, this tissue had been largely overlooked in vaccine science, but the NC State team’s findings could reposition it as a focal point in immunological research.