A rapidly dissolving film
"My 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," wrote Croyle.
"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."
Croyle's team began developing this technology in 2007 at the request of the National Institutes of Health. They got the idea of using film as a vaccine from a documentary about how the DNA of insects can be preserved in amber.
This was not an easy task to achieve as many of the early formulations either killed the organism as the film formed or crystallized it during storage. It took 450 tries in one year to find the recipe they use today.
Then, they worked on simplifying the process and making it faster to dry so that the vaccines could be produced more easily in order to be shipped sooner after they were produced. The question then remained: could the vaccine's potency be saved at room temperature in such a medium?
Room temperature storage
Their answer came when they discovered films containing viruses from their Ebola vaccine project made three years ago stored on the lab bench.
"On a whim, we rehydrated them and tested them to determine if the vaccine was still capable of inducing an immune response," wrote Croyle
"To our surprise, more than 95% of the viruses in the film were still active. To achieve this kind of shelf-life for an unrefrigerated vaccine was astonishing."
The new vaccination method is also less polluting. Conventional vaccination campaigns leave behind countless syringes and packaging.
"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," concluded Croyle.
The study was published in Science Advances.