New microneedle vaccine shows promise in pre-clinical trials

A single-use, self-administered microneedle technology has been developed to provide immunisation against infectious diseases. The technology has been validated by pre-clinical research trials and study was conducted at the University of Connecticut (UConn), US. 

According to the researchers, the concept of a single-injection vaccine is recognised as a preferable vaccination approach and has been investigated for many years. 

“It has been recognised for a long time that there is a need to eliminate many injections in conventional vaccination process,” said Assistant Professor Thanh Nguyen. “While booster and repeated shots of vaccines are important to sustain immune-protection, these injections are associated with pain, high costs and complicated injection schedules, causing a very low patient compliance. The issue becomes more problematic for patients in developing countries due to their limited access to healthcare providers.”

To overcome these problems, Nguyen’s lab developed a microneedle skin patch, which only requires a single administration to perform a programmable delayed release of vaccine.

To create the vaccine microneedle patch, Khanh Tran, a PhD student in Nguyen’s lab and the lead author of the published work, adapted the Nguyen’s previous work on microneedles called StampEd Assembly of Polymer Layer (SEAL) technology to assemble different microneedle components, including a cap, shell and vaccine core. These components are manufactured in an additive manner to create arrays of core-shell microneedles over a large area. The key to the new manufacturing process is to micro-mould vaccines into the shape of the microneedle core and insert all of the moulded vaccine cores into arrays of the microneedle shells at the same time.

In the pre-clinical trials, the researchers inserted microneedles loaded with a clinically available vaccine (Prevnar-13) into the skin of rats in a minimally invasive manner. The patch application caused no skin irritation during long-term implantation and triggered a high immune protection response against a lethal dose of infectious pneumococcal bacteria. The results from the one-time administration were similar to that obtained from multiple injections of the same vaccine over a period of approximately two months.

The team say the microneedle patch avoids any painful injections, offering a significant enhancement from the perspective of patients. The patch is small, portable and similar to a nicotine patch, which could be easily distributed to all people over the world for self-administration.

The researchers developed the microneedles to have a core-shell microstructure, in which the microneedle shells are made with biodegradable medical polymer that is US Food and Drug Administration (FDA)-approved for implants and offers unique drug-release kinetics, which allows a pre-programmed burst release of vaccine loads over a period of a few days to more than a month from a single administration. The microneedles can be easily inserted and fully embedded inside the dermal layer, due to the miniscule tips and smooth geometry of the needles.

“We are very excited for this achievement, as for the first time, a onetime-use and injection-free skin patch can be pre-programmed to release vaccines at different times to provide a long-term and effective immune protection,” Nguyen said. “The microneedle patch could facilitate the global effort for a complete vaccination process to eradicate dangerous infectious diseases and enable a quick distribution of vaccines. This could create a pan-community immune-protection at a global scale in the case of a pandemic such as the COVID-19.”

The study was published in Nature Biomedical Engineering.