Extending the shelf life of vaccines

Almost half of all vaccines are wasted. This is due to the logistical hurdles involved in transportation to different regions of the world. Most vaccines require strict temperature control from the manufacturing line to injection into a human arm. Maintaining a constant temperature along the cold chain (supply chain) is challenging under the best of circumstances. In sub-Saharan Africa and other developing regions, for example, limited transportation infrastructure and unreliable power supplies are compounding the already immense challenges of delivering viable vaccines.

Scientists at ETH Zurich’s Macromolecular Engineering and Organic Chemistry Laboratories and entrepreneurs at Colorado-based Nanoly Bioscience rose to the challenge and collaborated to develop a safe, versatile platform to increase the thermal stability of vaccines. your goal? To greatly improve the distribution of viable vaccines and reduce the economic cost of the cold chain.

Like Tupperware for proteins

“Think of it like an egg,” explains Bruno Marco-Dufort, a PhD student in Professor Mark Tibbitt’s Macromolecular Engineering Laboratory. “At room temperature or in the fridge, the egg retains its viscous protein structure, but as soon as it hits boiling water or the pan, its structure changes permanently.” Similarly, the proteins in a vaccine – as soon as they are exposed to certain temperatures, clump together you. Re-cooling will not reverse their denaturation – you cannot “boil” the egg.

So instead of changing Mother Nature, Marco-Dufort and the research team developed a new type of hydrogel, details of which have just been published in the journal scientific advances. The gel is based on a biocompatible, synthetic polymer called PEG, which serves as a protective coating for very large – but invisible to the naked eye – complex molecules, such as the proteins found in vaccines, antibodies or gene therapies. The packaging works like a molecular Tupperware, encapsulating the proteins and keeping them separate. It enables the proteins to withstand a higher range of temperature fluctuations. Instead of the traditional +2 to +8 degrees Celsius (35 to 45 degrees Fahrenheit) range for the cold chain, encapsulation allows for a 25 to 65 degrees Celsius (75 to 150 degrees Fahrenheit) range. Most importantly, the encapsulated cargo is released simply by adding a sugar solution, allowing for easy recovery of the vaccines as needed at their point of use.

use in cancer research

Besides a higher vaccine viability rate, the real game changer of this new biomedical hydrogel technology is the potential economic effect it could have in reducing costs and health risks associated with the cold chain. “In 2020, the total market for cold chain services (from manufacturing to distribution) was $17.2 billion and is expected to increase,” the researchers reported. Rising costs can have serious consequences for public health and public confidence when vaccines arrive through a compromised cold chain.

“Most vaccines are sensitive to heat and cold. This represents a major hurdle for global vaccination campaigns, since the costs of distributing and administering the vaccine often exceed the costs of production,” explains Marco-Dufort. While more investment will be required to support the cold chain, encapsulation offers a cost-saving solution that could be used to produce more vaccines, thereby saving more lives.

However, there is still a long way to go in terms of further research, safety studies and clinical trials before the hydrogels can be used for vaccine delivery. Their more immediate use is to transport heat-sensitive enzymes used, for example, in cancer research, or protein molecules for research into laboratory settings.

A step towards solving a global problem

While new biotechnology and cost savings are a step in the right direction, there are still enormous logistical, political and socio-economic challenges in solving the global problems related to vaccine equitable distribution and vaccine restraint. Marco-Dufort’s motivation is unbroken. His childhood experience in the Democratic Republic of the Congo has given him a deep understanding of the need for vaccines against infectious diseases, not only for COVID-19 but also for polio, meningitis and Ebola. He is more aware than most of the enormous challenges faced by people in sub-Saharan Africa in terms of access to vaccines, where infectious diseases are still widespread.

Mark Tibbitt, Bruno Marco-Dufort and the team’s work represent a major advance in the development of vaccine excipients. Their work also offers a glimmer of hope for a positive societal impact. Even a small easing of the economic factors associated with the distribution of vaccines, drugs, and biomedical research could have larger repercussions down the road.