Slovenian researchers, along with their German counterparts, have developed and tested a new method to deliver vaccines using mucoadhesive film that sticks to the cheek mucous membrane. This method could offer greater protection against respiratory infections compared to traditional methods, but further testing is needed.

The cheek mucous membrane has great potential for vaccination because of easy access and an abundance of immune system cells, which are essential for the triggering of innate and acquired immune responses, according to the Chemistry Institute, where some of the researchers work.

The film is made of a mucoadhesive layer with the vaccine formulation and a protective layer. The protective impermeable cellulose layer allows for the mucoadhesive layer to slowly dissolve and swell. The vaccine passes through the mucous membrane to the immune system cells, where it triggers the immune response.

This delivery method has the advantage of higher stability of the vaccine and an efficient delivery to the tissue that is the first to be in contact with pathogens.

The film can be used to deliver different vaccines, including plasmid DNA vaccines, vector vaccines and mRNA-based modern vaccines in lipid nanoparticles. The mRNA/LNP vaccines stayed stable and active for several days, the researchers said.

They have shown that this method of delivery provokes a strong local and systemic immune response in mice. The method also induced the production of mucosal IgAs, which play an important role in neutralising pathogens on the surface of the respiratory tract.

This delivery method could be especially important for booster shots as it is less invasive and could convince those reluctant to get vaccinated because of needles, the researchers said.

The method could ensure protection from respiratory infections, such as Covid-19, where a stronger mucous immunity is desired. The researchers estimate that this could help prevent infection in the early stages and reduce the possibility of the disease spreading.

The findings still have to be tested on models more closely resembling a human and in clinical trials.

The study was conducted by Slovenian researchers from the Chemistry Institute, the Faculty of Pharmacy at the University of Ljubljana, the UKC Ljubljana medical centre and the Golnik Clinic of Respiratory and Allergic Diseases, as well as German researchers. They published their findings in the Journal of Controlled Release.