Surveillance of invasive pneumococcal disease in Germany: surge in PCV13 serotypes and new challenges, 2017 to 2024.

BACKGROUNDPneumococcal vaccination has been recommended in Germany for adults aged ≥ 60 years (1998) and children aged < 2 years (2006), resulting in a reduction of pneumococcal disease incidence in vaccinated children and unvaccinated individuals through herd protection.AIMWe aimed to investigate serotype distribution of invasive pneumococcal disease (IPD) among children and adults in 2017-2024.METHODSWe analysed data of an ongoing nationwide surveillance of IPD. All isolates were serotyped by Neufeld's Quellung reaction.RESULTSIn total, 24,122 IPD isolates were analysed by the German Reference Laboratory for Streptococci. Over the study period, case numbers were lower during the COVID-19 pandemic and increased afterwards with higher proportion of pneumococcal conjugate vaccine (PCV)13 serotypes. Serotypes 22F and 33F, included in PCV15 and PCV20, showed only minor variations, whereas PCV20 unique serotypes were less frequently observed in 2022-2024. Serotype 3 persisted in IPD across all age groups, while serotype 4 disappeared in children and adolescents, but increased in adults, most prominently in 18-49-year-olds. Serotype 38 steeply increased in 2023/24, among children aged < 2 years and older adults.CONCLUSIONThe concerning increase of PCV13 serotype IPD in Germany might be related to low vaccination uptake, resulting in inefficient herd protection. The dominance of serotype 3 and the rise of serotype 4 among adults highlight the importance of direct protection and support the current national vaccination recommendation for adults aged ≥ 60 years. The increase in serotype 38 IPD among young children and older adults might indicate a replacement phenomenon, highlighting the importance of IPD serotype surveillance.