Characterisation of factors contributing to the performance of nonwoven fibrous matrices as substrates for adenovirus vectored vaccine stabilisation
The global network of fridges and freezers known as the "cold chain" can account for a significant proportion of the total cost of vaccination and is susceptible to failure. Cost-efficient techniques to enhance stability of vaccines could prevent such losses and improve vaccination coverage, particularly in low income countries. We have previously reported a novel, potentially less expensive thermostabilisation approach using a combination of simple sugars and glass micro-fibrous matrix, achieving an excellent recovery of vaccines after storage at supraphysiological temperatures. This matrix is, however, prone to fragmentation and currently not suitable for clinical translation. Here, we report an investigation of alternative, potentially GMP compatible, fibrous matrices. A number of commercially-available matrices permitted good protein recovery, quality of sugar glass and moisture content of the dried product but did not achieve the thermostabilisation performance of the original glass fibre matrix. We therefore further investigated physical and chemical characteristics of the glass fibre matrix and its components. Our investigation shows that the polyvinyl alcohol present in the glass fibre matrix assists vaccine stability. This finding enabled us to develop a custom-produced matrix with encouraging performance, as an initial step towards a biocompatible matrix for clinical translation. We discuss the path to transfer of the technology into clinical use, including potential obstacles.