There are several issues associated with vaccine stability, for example, vaccine thermosensitivity. Currently, vaccines must be stored and distributed at between 2Â°-8Â° or -20Â°C, as they are not stable at an ambient temperature for the duration of their shelf life. Some are stable up to 37Â°C for days or weeks. As nearly half of vaccines contain aluminium salt adjuvant, they are freeze-sensitive. Nearly all live attenuated vaccines, being lyophilized, are typically sensitive to heat and not to freezing. Temperature excursions, low being more common then high can also occur in both developing and developed countries, the impact of which can be high, with vaccine wastage, potentially inadequate protection from compromised vaccines, and the administrative burden of handling cold chain excursions and also, wasted funds.
According to Dr Dexiang Chen, Technical Officer, PATH, who joined us at the World Vaccine Manufacturing Congress in Washington 2012, the development of thermostable vaccines could help to prevent this vaccine wastage, and solve many of the problems associated with thermosensitivity. The targets for this research are to develop a vaccine stable at an ambient temperature, stable at controlled temperature chain and stable at both cold chain and controlled temperature chain.
Some of the challenges facing this research are: regulatory hurdles and the inherent cost of reformulating existing vaccines could be high. Validating this cost is difficult as quantifying the benefits from improved stability is also difficult. There would also be a need for new regulation, policy and logistic systems, in addition to the new formulation technologies, adding more cost to the development of thermostable vaccines.
Why not download the full presentation and find out more about the opportunities and challenges of developing thermostable vaccines.