A Flu Vaccine in Your Dental Floss? Researchers Tout Benefits, Critics Question Safety

Written by Suzanne Burdick, Ph.D. on August 2, 2025. Posted in Current News

People could someday get a flu vaccine by flossing their teeth, according to a study published last week in Nature Biomedical Engineering. The authors of the study said their findings “establish floss-based vaccination as a simple, needle-free strategy that enhances vaccine delivery and immune activation.”

But critics said the study raises questions about informed consent and how the vaccine dose would be controlled.

The study is the first to show that applying a vaccine to the gum crevice of mice by flossing their teeth with special dental floss activated a strong immune response, Harvinder Gill, Ph.D., a professor in nanomedicine at North Carolina State University and the study’s senior author, told The Defender.

“Nobody would’ve thought that you could do that,” he said.

Delivering a vaccine to the gum crevice could make the vaccine more effective than a vaccine administered by a syringe — plus, the approach is painless, Gill said.

But epidemiologist Nicolas Hulscher questioned the technology’s safety. “This vaccine technology carries the significant risk of uncontrolled dosing — where each individual administration will yield a different result,” he said.

Jessica Rose, Ph.D., an immunologist and biochemist, said she fears people would use the dental floss without knowing it contained a vaccine.

For instance, pharmaceutical company representatives could give doctors or dentists “free samples” to give patients, without disclosing the product’s risks. “The opportunity to provide informed consent will be impossible in this scenario,” Rose said.

Gill pushed back, saying the technology is “all about choice” because it gives people who want to get vaccinated an option other than shots and nasal sprays.

Floss sparked antibody production in mice, study showed

For the study, researchers flossed the teeth of mice using thread coated with different kinds of antigens.

Antigens are markers that alert the body to harmful foreign substances and trigger an immune response. They are a vaccine’s active ingredient, according to the Centers for Disease Control and Prevention.

In one test, the researchers used floss coated with a fluorescently labeled protein. They found that 75% of the protein was successfully delivered to the mouse’s gums.

The mice still had elevated antibodies in their noses, lungs, feces and spleens two months after flossing, according to Science.

In addition to protein antigens, the researchers tested nanoparticles, peptides, mRNA molecules, an inactivated flu virus and a live-attenuated flu virus, Gill said.

With each, the flossing approach effectively delivered the antigen to the body, prompting a strong immune response, including heightened antibody and T-cell production, and enlarged lymph nodes.

“We covered all vaccine types, so in that sense, the approach should be applicable” to all vaccines, Gill said. But that doesn’t mean floss vaccines will be on the market soon.

“Of course, you have to modify,” Gill said. “You have to optimize the formulation. And a lot of work needs to be done so that you could make it work for each different kind of vaccine.”

The researchers also found that eating or drinking immediately after flossing did not inhibit the vaccine’s effectiveness.

To test the method in people, the researchers asked nearly 30 healthy people to floss with dental picks coated with colored food dye. About 60% of the dye was delivered to their gums.

The majority of the participants said they would prefer a floss vaccine to an injection.

Why would floss vaccines be more effective than shots?

The floss method delivers the vaccine in the gum crevice, a uniquely permeable mucosal surface, where the body most needs to rally an immune response, Gill said.

Mucosal surfaces are the body’s interfacing tissues — such as the respiratory tract, gut and bladder — that “are in constant contact with microorganisms and play a crucial role in protecting host tissues from microbial invasion,” according to ScienceDirect.

It’s best if a vaccine triggers the body to produce antibodies on or near mucosal surfaces, since that’s likely where the pathogen is first contacting the body, Gill said.

Intramuscular shots mostly trigger antibody production in the blood and other bodily tissues, meaning they don’t provide good protection at mucosal surfaces, he said.

However, most mucosal surfaces don’t absorb proteins well, which makes them poor sites for delivering vaccines. The gum crevice is an exception.

“It is, by nature, highly permeable, so it can absorb large molecules,” Gill said.

Putting a vaccine in gum crevices prompts the body to mount a strong immune response at the mucosal surface. “So if we can do that, we actually make a better vaccine using the same vaccine,” Gill said.

“Just by changing the administration route, you can create a first line of defense on the mucosal surfaces. … That’s why we are very excited.”

But what about dosing?

According to the study, the floss method could potentially deliver roughly the same amount of flu vaccine as a flu shot or spray.

But exact dosage guidelines still need to be developed.

Correct dosing would depend on how thick the floss is coated with the vaccine and how effective the floss is at delivering the vaccine to the gum crevice, the authors said in their report.

The U.S. Food and Drug Administration (FDA) would have to do its job by requiring a specific and correct dosage for the technology, said Dr. Meryl Nass, a physician and outspoken critic of pandemic-era overreach.

“FDA basically broke its own rules” when it granted emergency use authorization for the mRNA COVID-19 vaccines, she said. “So what we really need to do is come down hard on the FDA” to ensure that it requires correct dosages for all vaccine products.

When the FDA authorized mRNA COVID-19 vaccines, the agency failed to specify an exact mRNA dose, since it’s unknown how much mRNA the recipient’s body will generate in response to the vaccine.

Gill agreed that COVID-19 mRNA vaccines were fast-tracked given the pandemic emergency, but said there’s no reason why the FDA would “short-circuit” its procedures for licensing a floss vaccine.

However, studies on larger animals would be needed before the FDA can assess the technology, Gill said.

Informed consent issues abound 

Gill acknowledged that the technology is controversial. “There are different viewpoints and we don’t have to agree. It’s a debate.”

Gill said he is “only a researcher who’s very curious and wants to do different things, novel things, and find out answers … it’s like Star Trek ‘where no one has gone before.’ That’s what we are trying to do in our lab.”

In 2020, the Defense Advanced Research Projects Agency (DARPA) recognized Gill for his research on using pollen to deliver vaccines.

When asked about the informed consent implications of such technologies, Gill said it’s “remotely possible” that an individual or the military could use non-syringe vaccination methods to do things “they’re not supposed to do,” such as mass vaccinating a population without their consent.

“If everybody follows the law, then we shouldn’t have problems,” he said.

Rose said she’s skeptical. “I do not see how floss vaccines could possibly work in a realistic or ‘real-world’ setting, especially in the face of the rightly placed mistrust in the ‘health care’ system due to preposterous implementations of ‘measures’ during the COVID era.”

A spokesperson at the U.S. Department of Health and Human Services (HHS) said U.S. Health Secretary Robert F. Kennedy Jr. and HHS “have consistently emphasized the importance of informed consent, which is an important part of ethical medical practice.”

The Defender then asked if HHS would develop informational handouts with “truthful and sufficient information” for all medical procedures and medications, and support patients in reviewing the handouts so they can give informed consent.

HHS did not respond by deadline.

source  childrenshealthdefense.org

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