AF03, An Alternative Squalene Emulsion‐Based Vaccine Adjuvant Prepared by a Phase Inversion Temperature Method

AF03 is a squalene‐based emulsion adjuvant that is present in the adjuvanted pandemic influenza vaccine, Humenza™. In this report, we describe the design and development of this novel adjuvant formulation from the selection of the oil and surfactant system used in the adjuvant composition to the phase inversion temperature emulsification process that afforded AF03 as a long‐term stable and well calibrated oil‐in‐water emulsion. The emulsion was characterized by its particle sizes, surface and interfacial tensions, viscosity, and long‐term stability.