A doctoral student at the University of Oxford’s Institute of Biomedical Engineering is exploring a needle-free ultrasound vaccine. This approach utilizes bubbles that respond to sound waves.
This delivery method could be suitable for patients with needle phobia. It may also lead to a stronger immune response.
Some experts think that this approach could be revolutionary, while others doubt that it could ever replace traditional injection methods.
During the COVID-19 pandemic, vaccination's role in public health became evermore critical. But issues like needle phobia presented issues—a problem considering that most vaccinations are administered via injection. In response, researchers have been exploring other modes of administration.
Some vaccinations can be given orally (in the case of rotavirus, adenovirus, cholera, and typhoid) or intranasally (in the case of influenza), but ultrasound is yet another possibility.
According to a press release issued by the Acoustical Society of America (ASA), Darcy Dunn-Lawless, a doctoral student at the University of Oxford’s Institute of Biomedical Engineering, is hoping to one day see a pain-free, needle-free ultrasound vaccine alternative to injections as well as a potentially beneficial way of creating a stronger immune response to vaccinations.
“[P]ublic health depends on people being willing to receive vaccines, which are often administered by a jab [injection],” the authors of the aforementioned press release state.
Needle phobia has real consequences, both on the individual and public health levels. According to a PLoS One survey of 2,098 participants, 63.2% reported experiencing needle phobia, with most citing general anxiety and fear of pain as causes. Furthermore, 33.1% of those surveyed specified injection vaccinations (versus, say, blood draw or donation) as a key phobia.
Recent research published in Psychological Medicine also found that out of 15,014 adults living in the United Kingdom, 26.2% had an injection-related phobia. Of these adults, 22% of these individuals reported COVID-19 vaccination hesitancy.
How do ultrasound vaccinations work?
Dunn-Lawless says that the ultrasound vaccination method relies on an acoustic effect—referred to as cavitation—which centers on bubbles responding to a sound wave. “We aim to harness the concentrated bursts of mechanical energy produced by these bubble collapses in three main ways,” she says:
First, the energy clears passages through the outer layer of dead skin cells, enabling the vaccine molecules to push through. Next, it pumps the molecules into passages and opens the membranes surrounding the cells themselves (which is especially crucial for vaccines that only work from within the cell itself).
Researchers have been exploring this method for years. As a 2016 article published in Advances in Experimental Medicine and Biology notes, bubble-assisted ultrasound vaccination is a “versatile technology with great potential in immunotherapy and vaccination.”
The potential pros and cons of ultrasound vaccine delivery
Beyond serving as an alternative to injections, the ultrasound delivery method could potentially deliver therapeutic antibodies (like immunotherapy) and cytokine-encoding nucleic acids (like cytokine gene therapy) directly into diseased tissues.
Additionally, the ASA says that ultrasound vaccination may lead to a stronger immune response. Dunn-Lawless tells MDLinx.com that researchers are entirely sure why this immune response is so strong. “Our current theory is that our acoustic delivery system provides something that an injection alone does not: a physical way to get molecules into cells,” she says. “Some vaccines, like the DNA vaccine model we have been using, need to get inside cells to work. There is evidence that cavitation can open up the membrane around cells, letting molecules in and therefore increasing the immune effect.”
But while the ultrasound technique may offer clear benefits, it also has its drawbacks, the ASA reports. In vivo studies, the ultrasound technique delivered 700 times fewer vaccine molecules through the cavitation approach versus a traditional injection. Moreover, tissue damage can occur when excessive cavitation is applied to the body. Thus, Dunn-Lawless says, more research is needed to determine how safe this method might be.
What do healthcare practitioners think? Some experts have doubts about this technology’s viability. Jared L. Ross, DO, a board-certified emergency medicine physician in Bolivar, MO, wonders if needle-free vaccines could ever successfully replace traditional injections. For example, Dr. Ross cites FluMist, a nasal spray influenza vaccine approved in 2003: “It has failed to gain traction even 20 plus years later. Every pandemic—from H1N1 [in] 2009 to influenza in 2017 to COVID-19— has reinvigorated interest in finding a mass vaccination strategy for those with fear of needles…however none have been successful.”
Other HCPs have more hope. Kelvin Fernandez, MD, a resident physician at Newark Beth Israel Medical Center in Newark, NJ, believes that an ultrasound vaccine option would transform the vaccine delivery process.
“It would increase vaccination acceptance rates dramatically, [which is] essential to mitigate future public health crises,” Dr. Fernandez says. He says that he can see adults and children with needle phobias benefiting from this delivery method, in addition to those with specific health conditions that might inhibit a vaccination.
What are the next steps in making this a reality?
In the short term, Dunn-Lawless tells MDLinx.com that researchers will explore making the technique as safe and effective as possible. Next, they’ll use that information to design an improved prototype device.
“After that, we will need to study the system more with animal trials and demonstrate that the immune responses we've seen so far translate into actual protection from disease,” Dunn-Lawless says. “Then, the really exciting step: trialing the system with humans for the first time. There is a lot of work to be done before that point, but we are hopeful that we can reach it sooner rather than later.”