Advanced drying technologies for vaccine products

Vaccines continue to be the frontline protection against infectious disease, preventing epidemics and taming outbreaks. Distribution of vaccine products is challenging; product quality must be protected during shipment and storage to ensure stability throughout shelf-life. Drying is a critical process for removing water and oxygen to prevent product degradation. Recent advances in technologies for aseptic drying may provide significant benefits in product quality, supply reliability and productivity, with reduced cost. This review discusses factors that must be considered during product development across the range of currently available vaccine formats. Current operations are predominantly based on lyophilization processes using heating fluids in the shelves to sublimate vapor from product in vials. Over the last decade, equipment design has progressed to allow new options for final product manufacturing, including potential for continuous processing. Microwave energy is being developed as a new heating source with more homogeneous penetration leading to faster drying cycles. Spray-drying and spray-freeze drying are now available for aseptic production of a flowable bulk powder for dosing in a wide variety of container closure systems. These novel systems are driving reductions in cost and improved cycle time, while maintaining product sterility and stability.