Flu Shot Delivered Via Dental Floss? Scientists Test Needle-Free Option in Mice

A recent study published in Nature Biomedical Engineering reveals that researchers in the U.S. have developed a method of delivering a flu vaccine using coated dental floss inserted into the gums of mice.

After three rounds of flossing with inactivated flu virus, the mice developed strong immune responses — and all survived a subsequent exposure to live flu virus. Unvaccinated mice, by contrast, did not survive.

The study’s lead author, Dr. Harvinder Gill of North Carolina State University, was inspired by research showing that the gingival sulcus—the space between teeth and gums—is highly absorbent. This prompted the idea that the gumline could be used as a route for vaccination.

“If it is highly permeable, could we not use it for vaccination?” – Dr. Gill

Testing on Humans

Following the success in mice, the researchers tested the concept in humans—not with virus-coated floss, but with dental picks dipped in food dye. Twenty-seven healthy adults flossed with the dyed picks, resulting in about 60% absorption of the dye into their gumline. Most participants indicated they would prefer this method over a traditional needle-based vaccine.

The researchers suggest that one day, this approach could be used in dental offices or for self-application.

Concerns and Considerations

While the method offers a needle-free alternative, several concerns remain:

• The possibility of vaccines being administered without clear, informed consent, especially in routine dental visits.

• The method’s effectiveness and safety in people with gum disease, which affects approximately 40% of adults.

• The broader implications of embedding pharmaceutical delivery into everyday personal care products.

Experts not involved with the study have expressed caution. Dr. William Giannobile, dean of Harvard’s School of Dental Medicine, noted that while the immune response in mice was strong, it is unclear whether similar results would occur in humans with varying oral health.

Broader Context and Canadian Status

This dental floss vaccine study is part of a wider movement exploring alternative vaccine delivery methods, including edible vaccines, transdermal patches, nasal sprays, and other needle-free technologies. These approaches raise important questions about transparency, medical ethics, and patient choice.

As of July 2025, there is no indication that Canada is implementing or planning to adopt dental floss-based vaccine delivery methods. Canadian health authorities have not announced any trials or programs involving this technology.

Key Points:

• Flu vaccine delivered via coated floss showed protection in mice

• Human test with dyed floss showed 60% absorption and preference over needles

• More research needed, particularly regarding gum disease patients

• Raises questions about informed consent and routine medical procedures

• No current implementation or plans for this method in Canada

Source:
Inampudi, A. Engineers transform dental floss into needle-free vaccine. Nature Biomedical Engineering, July 22, 2025.

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