Eliminating ‘Cold-Chain’ Requirements Could Reduce Budgets and Save Lives

Most health officials say ‘live vaccines are a critical component of global health that saves millions of lives each year.’ 

Unfortunately, almost all ‘live vaccines’ are thermally labile and must be stored at temperatures between 2–8 °C to maintain their efficacy, said researchers from McMaster University in Ontario, Canada, on May 21, 2019. 

A thermally labile compound breaks down when exposed to high temperatures. 

This uninterrupted temperature requirement is known as the “cold chain”, says the World Health Organization. 

And this need for a ‘cold chain’ presents significant economic costs and logistic problems for vaccination programs in developing countries. 

To potentially meet this ‘cold chain’ requirement, researchers from McMaster University in Ontario, Canada found an affordable, durable solution that protects vaccines without keeping them cold. 

In this pre-human, mice study published in Nature, these McMaster researchers demonstrated that the in vitro infectivity of live viruses, and the in vivo immunogenicity of their corresponding vaccines, can be saved for up to 3 months at 40 °C by drying them in a pullulan and trehalose mixture. 

Trehalose is a disaccharide that is commonly used as a cryoprotectant and stabilizing agent. 

While pullulan is a polysaccharide with good film-forming abilities that are used in the food industry to extend the shelf-life of food. 

In addition to being readily available and inexpensive, these 2 compounds are also approved by the US Food and Drug Administration. 

Vaccines containing live-enveloped viruses were chosen for this study because they are intrinsically more unstable than other types of vaccines. 

Overall, these researchers showed a simple and versatile method for thermally protecting viral vectors using pullulan and trehalose films. This technology has the potential to solve the cold chain problem and in turn greatly improving global health by providing people around the world with access to vaccines. 

The authors thank the Natural Sciences and Engineering Research Council of Canada, the Canadian Institutes of Health Research and Grand Challenges Canada for funding. 

They also thank the Canadian Foundation for Innovation and the Ontario Ministry of Research and Innovation for Infrastructure funding to the Biointerfaces Institute at McMaster University. M.S.M. was supported by a CIHR New Investigator Award and an Early Researcher Award from the Ontario Ministry of Research, Innovation, and Science.

These researchers, Vincent Leung, Alexandra Szewczyk, Sana Jahanshahi-Anbuhi, and Carlos D. M. Filipe, did not disclose conflicts of interest.