Liguria, an administrative region in northern Italy characterized by a decade of high PCV coverage in paediatric age group, has issued new PCV13 recommendations for free active immunization in adults with risk factors and subjects aged ≥ 70 years old. Main aims of this study are: (1) a descriptive epidemiology of the clinical burden of lower respiratory tract infections (LRTI) in adults ≥18 years of age; and (2) a crossover evaluation of the effect of introduction of PCV13 vaccination in adults aged ≥70 years old, in terms of ED accesses for LRTI, obtained by a Syndrome Surveillance System (SSS). The ED access, chief complaint based SSS will allow an active surveillance of a population cohort of>430 000 individuals resident in Genoa metropolitan area, aged ≥18 years old, for a period of 60 months. During pre-PCV period, annual cumulative incidence of ED accesses for LRTI was equal to 7/1000 and 2% in ≥65 and ≥85 year adults, respectively. In ≥65 years adults, more than 70% of subjects identified by the SSS has at least one risk condition, with a peak of 87% in ≥85 year cohort. New Ligurian PCV13 recommendations can potentially reach more than 75% of ED accesses for LRTI. Data highlights the heavy impact of LRTI in terms of ED accesses, especially in the elderly and subjects with chronic conditions and the usefulness of SSS tool for monitoring PCV vaccination effect.