Squalene is a squalene-based oil-in-water nano-emulsion with a formulation similar to MF59 that has been licensed in Europe for adjuvanted flu vaccines. Squalene is an oil more readily metabolized than the paraffin oil used in Freund's adjuvants. Squalene oil-in-water emulsion elicit both cellular (Th1) and humoral (Th2) immune responses.