Invasive pneumococcal disease before, during and after the SARS-CoV-2 pandemic.

BACKGROUND The aim of this study was to analyse the changes in the incidence of invasive pneumococcal disease (IPD) before, during, and after the SARS-CoV-2 pandemic.

METHODS Cases of IPD detected through active epidemiological surveillance in Navarre, Spain, from 2018 to 2024 were analysed. Incidence rates were compared across three periods: pre-pandemic (2018-2019), pandemic (2020-2022), and post-pandemic (2023-2024) overall and by age groups and serotypes RESULTS: From 2018 to 2024, a total of 437 IPD cases were diagnosed in Navarre. The incidence of IPD decreased from 11.6 to 5.6 cases per 100,000 persons during the pandemic period and return to 13.0 cases per 100,000 persons in the post-pandemic period. The incidence decreased across all age groups in both, serotypes included and not included in the 13-valent pneumococcal conjugate vaccine (PCV13). Serotype 3 was the most frequent in the three periods, representing 20.3% of all cases. In the post-pandemic period, 35.2% of cases were due to serotypes included in the PCV-13, 45.7% in the PCV-15 and 64.2% in the PCV-20.

CONCLUSIONS During the SARS-CoV-2 pandemic, the incidence of IPD decreased across all age groups for both, PCV13-included and not included serotypes. In the post-pandemic period, incidence returned to pre-pandemic levels. Whole-genome sequencing techniques helped to serotyping of S. pneumoniae, and thus, complemented epidemiological surveillance.