Suspension properties and characterization of aluminum-adjuvanted vaccines

Aluminum-containing adjuvants are commonly used in vaccines to elicit an enhanced immune response in patients. The structure and surface characteristics of aluminum-containing adjuvants govern their interaction with antigens and its formation of antigen–adjuvant complexes. Furthermore, the individual properties of the adjuvant and antigen and interactions between them significantly impact the macroscopic behavior of vaccine suspensions. Herein, the bulk suspension properties of aluminum-adjuvanted vaccines, such as particle size, surface charge, and sedimentation rate, and techniques used to characterize these properties are reviewed. The development of aluminum-adjuvanted vaccines requires evaluation of factors such as characterization of the flocculation state of the suspension and the impact of processing stress on particle characteristics. From clinical development to commercial manufacturing, a fundamental understanding of aluminum-adjuvanted vaccine suspension behavior should be considered.