As the novel coronavirus has shown us, a communicable disease without a vaccine can cause widespread devastation. Fortunately, modern medicine has successfully engineered a host of vaccines that are both safe and effective in preventing diseases that can have severe symptoms and life-long side effects. Complications, however, arise in getting these vaccines to remote or dangerous places as they’re notoriously difficult to transport, requiring constant refrigeration to avoid spoiling. New research published in the journal Scientific Reports details the groundbreaking discovery of a method for preventing warm vaccines from degrading by coating the proteins in a protective silica shell.
Pre-existing vaccine transportation methods meant the formulas were safe between 2 and 8°C (35.6 and 46.4°F) but above this their proteins began to unravel and render the vaccine ineffective. The complication meant millions of children from remote parts of the Earth were unable to access life-saving inoculations, putting themselves and other children at risk as townships are unable to form herd immunity to threatening illnesses.
This new formula for heat-tolerant vaccines involves encasing the protein molecules in a silica coat in a process called ensilication. The results showed that vaccines made in this way could be heated to 100°C (212°F) or left at room temperature for up to three years before showing signs of damage to the protein molecules.
The study saw researchers send both ensilicated and regular samples of the tetanus vaccine from Bath to Newcastle, both in the UK, using the ordinary (non-refrigerated) postal service. The journey spanned over 300 miles (482 kilometers), meaning the vaccines were in transit for around a day or two.
Upon arrival, the researchers injected the vaccines into mice and found that an immune response was only triggered in those mice given the ensilicated version of the vaccine, showing the formula was active and effective. Those injected with the conventional tetanus vaccinations were not found to trigger an immune response, indicating the two-day journey in uncontrolled temperature conditions had damaged the medicine.
The exciting finding shows that the ensilication process can preserve vaccinations that currently can’t survive the journey to the areas of the world where they’re needed the most. At the moment, around a half of vaccine doses end up in the bin due to improper storage conditions, and in 2018, according to the World Health Organization (WHO), 19.4 million infants were unable to receive routine life-saving vaccinations.
While exciting news, there is still some work to be done before all vaccines can be made heat-tolerant through ensilication as the research has only tested its efficacy on tetanus so far. The researcher’s intent to continue developing thermally stable vaccines for diseases such as diphtheria and pertussis.
"Ultimately, we want to make important medicines stable so they can be more widely available," said Dr Asel Sartbaeva, who led the project from the University of Bath's Department of Chemistry, in a statement. "The aim is to eradicate vaccine-preventable diseases in low income countries by using thermally stable vaccines and cutting out dependence on cold chain."
