MF59

MF59 is an additive used in some flu vaccines to help the immune system respond more effectively. It is an oil-in-water emulsion, meaning tiny oil droplets are dispersed in water, which enhances the body’s recognition of the vaccine's antigens. This results in a stronger and broader immune response, especially beneficial for populations like older adults who may have weaker immune systems. MF59 has been safely used in flu vaccines since the early 2000s and contributes to improved vaccine effectiveness without significant side effects.