In 1986 the Ottawa Charter underlined the importance of advocacy in health. This article analyzes the role of advocacy in Public Health making the case of immunization, whose coverage rates are decreasing in many countries. An effective advocacy action could counteract the growing phenomenon of the vaccine hesitancy within both the general population and an increasing share of healthcare providers as well as contrast antivax movements' action. We identify who are the advocates focusing on Italy and on the crucial role of scientific societies which share the responsibility of making the latest scientific evidence and most effective infectious diseases' control strategies available to health policy makers. The Italian Society of Hygiene (SItI) has been actively engaged for several years in a number of initiatives of advocacy communication and vaccines including research, training, media exposure and a dedicated website portal (vaccinarSi).