vaccine additive role a role inheres in a material entity, that has been added into a vaccine's formulation by the manufacture for a specific purpose. For example: adjuvant to enhance the effect of immunogen, perservatives, stablizers and those materials added for affecting PH and isotonicity. Page 73, Chapter 6, Vaccine, 5th Edition. EXPERT CONSULT by Plotkin SA., et. al. 2008 YL,YH vaccine component role