Researchers created new type of mouth-dissolving vaccine

In the midst of the SARS-CoV-2 coronavirus epidemic, immunologists are working harder to develop an effective vaccine as quickly as possible. Once developed, this vaccine must be produced, packaged and distributed worldwide so that it can be administered to populations. However, a vaccination campaign is not without its pitfalls: it is necessary to make suitable bottles, store the vaccines in refrigerated containers, produce hundreds of thousands of needles, etc. These prerequisites are time consuming and costly. This is why a team of researchers has recently developed a whole new type of vaccination, taking the form of a small film dissolving in the mouth. The vaccine film, fast and very inexpensive to produce, does not require any needle or refrigerated storage.

The research group has developed a novel method to stabilize live viruses and other biological medicines in a rapidly dissolving film that does not require refrigeration and can be given by mouth. Since the ingredients to make the film are inexpensive and the process is relatively simple, it could make vaccine campaigns much more affordable. Large quantities could be shipped and distributed easily given its flat, space saving shape.

Globally, vaccination rates have improved over the past decade, but are still too low – 13.5 million children were not vaccinated in 2018. This new technology, recently published in the journal Science Advances, has the potential to dramatically improve global access to vaccines and other biological medicines.

A technique inspired by hard candy

The research team began developing this technology in 2007, when the National Institutes of Health asked us to develop a needle-free, shelf-stable delivery method for a vaccine.

The idea of developing a film was inspired by a documentary about how the DNA of insects and other living things can be preserved for millions of years in amber. This got them into thinking about hard candy.

It was a simple idea, yet no one had tried it. So they went to work mixing a variety of formulations containing natural ingredients like sugars and salts and testing them for their ability to form a solid amber-like candy.

The vaccine film created by the researchers is simple and inexpensive to produce. In addition, it can be stored at room temperature. Credit: Maria Croyle

Initially, many of the preparations they tested either killed the organism as the film formed or crystallized during storage, shredding the virus or the bacteria they were trying to preserve.

But finally, after about 450 tries over the course of a year, they found a formulation that could suspend viruses and bacteria in a peelable film.

As they gained more experience with the production process, they worked to simplify it so extensive technical training would not be needed to make it. Additionally, they tweaked the ingredients so they would dry faster, enabling one to make a batch of vaccine in the morning and ship it after lunch.

All stored vaccines lose their potency over time. The rate at which they do so mostly depends on the temperature at which they are kept. Keeping vaccines continuously refrigerated is difficult and expensive – and in some parts of the world, nearly impossible. So creating a vaccine that can be stored and transported at room temperature is a huge advantage.

Vaccine films: they keep viruses stable and are easy to administer

The biggest breakthrough in this project came when the researchers finished their work on the Ebola vaccine and found films containing the virus made three years ago, stored in a sealed container on the laboratory bench. On a whim, they rehydrated and tested them to determine if the vaccine was still capable of inducing an immune response. Over 95% of the viruses in the film were still active. Achieving this type of shelf life for an unrefrigerated vaccine was amazing.

Structure of the vaccine film. Credits: Irnela Bajrovic et al. 2020

The ecological footprint left by global immunization campaigns is not often considered. The 2004 Philippine Measles Elimination Campaign, which immunized 18 million children in one month, generated 19.5 million syringes, or 143 tons of sharps waste and nearly 80 tons of nonhazardous waste – empty vials, syringe wrappers, caps, cotton swabs and packaging. The implications for a larger campaign are significant.

“Our film, by contrast, can be distributed by health workers equipped with only an envelope containing the vaccine. Once taken, it will leave no trace, except for a healthy global population.” the author said.


Novel technology for storage and distribution of live vaccines and other biological medicines at ambient temperature

Irnela Bajrovic, Stephen C. Schafer, Dwight K. Romanovicz and Maria A. Croyle

Science Advances  04 Mar 2020:
Vol. 6, no. 10, eaau4819

DOI: 10.1126/sciadv.aau4819

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