Indirect Effect of Pneumococcal Conjugate Vaccines on Pneumococcal Colonization: Persistence and Dynamics of Vaccine Serotypes in Sicily (Italy) 11 Years Postintroduction, 2009–2020

Despite sustained high pediatric vaccination, pneumococcal carriage remained substantial across all ages, with persistent circulation of vaccine and non-vaccine serotypes. Viral co-infection, particularly with hRSV, appeared to facilitate colonization. These findings underscore the need for ongoing carriage surveillance and evolving vaccine strategies to address changing pneumococcal ecology.