Analysis of Sequential Pneumococcal Vaccination Coverage in the Elderly Resident Population of the Viterbo Local Health Authority from 2018 to 2023

Background: Pneumococcal disease is a significant health burden, particularly among older adults and individuals with chronic conditions. Sequential pneumococcal vaccination (PCV13 followed by PPSV23) have been recommended in Italy since 2017 for its demonstrated efficacy, safety, and cost-effectiveness in preventing invasive pneumococcal disease (IPD). Nevertheless, limited data are available on the sequential pneumococcal vaccination coverage in Italy. This study aimed to evaluate the coverage and trends of sequential pneumococcal vaccination among individuals turning 65 years old within the Viterbo Local Health Authority between 2018 and 2023. Methods: A retrospective cohort study was conducted using data from the Regional Vaccination Registry (AVR), a comprehensive digital vaccination dataset. Vaccination coverage was calculated based on individuals completing the sequential pneumococcal vaccination within two years from turning 65 years old. Trends as well as subgroup variations based on sex, citizenship, district of residence, and municipality size were analyzed. Results: Among 27,657 individuals turning 65 years of age during the study period, only 2.32% completed the sequential pneumococcal vaccination. Coverage increased steadily from 2018 (0.60%) to a peak in 2020 (3.27%), followed by a plateau and a decline in 2023 (2.53%). Coverage varied across demographic and geographic subgroups: females (2.58%) had higher coverage than males (2.04%), Italian citizens (2.45%) exceeded foreign residents (0.64%), and residents in District C (3.03%) led over District A (1.08%). Smaller municipalities (≤10,000 inhabitants) showed higher coverage (2.52%) than larger ones (1.98%). Conclusion: Adherence to sequential pneumococcal vaccination has been very low throughout the considered study period. This is a very relevant information to consider in the view of new available pneumococcal vaccines for the elderly immunization. Furthermore, geographic and demographic differences highlight the need for targeted public health interventions.