Nationwide trends of invasive pneumococcal disease in Spain (2009-2019) in children and adults during the pneumococcal conjugate vaccine era.

Abstract

Background: Introduction of pneumococcal conjugate vaccines (PCVs) has reduced the disease caused by vaccine serotypes in children, providing herd protection to adults. However, the emergence of nonvaccine serotypes is of great concern worldwide. Methods: This study includes national laboratory data from invasive pneumococcal disease (IPD) cases that affected pediatric and adult populations during 2009-2019. The impact of implementing different vaccine strategies for immunocompetent adults by comparing Spanish regions that used the 13-valent PCV (PCV13) vs regions that used the 23-valent pneumococcal polysaccharide vaccine (PPV23) was also analyzed for 2017-2019. Results: The overall reductions in IPD cases by PCV13 serotypes in children and adults were 88% and 59%, respectively, during 2009-2019, with a constant increase in serotype 8 in adults since 2015. IPD cases by additional serotypes covered by PPV23 increased from 20% in 2009 to 52% in 2019. In children, serotype 24F was the most frequent in 2019, whereas serotypes 3 and 8 accounted for 36% of IPD cases in adults. Introduction of PCV13 or PPV23 in the adult calendar of certain Spanish regions reduced the IPD cases by PCV13 serotypes by up to 25% and 11%, respectively, showing a decrease of serotype 3 when PCV13 was used. Conclusions: Use of PCV13 in children has affected the epidemiology, reducing the burden of IPD in children but also in adults by herd protection; however, the increase in serotype 8 in adults is worrisome. Vaccination with PCV13 in adults seems to control IPD cases by PCV13 serotypes including serotype 3.