Initial vaccination platform against S. pneumoniae shapes antibody profiles upon revaccination with pneumococcal conjugate vaccine in older adults.

Currently, two types of Streptococcus pneumoniae vaccines are approved by the Food and Drug Administration (FDA): pneumococcal conjugate vaccine (PCV) and plain polysaccharide vaccine (PPSV). Here, we characterized how antibody profiles against select S. pneumoniae serotypes (Pn1, Pn3, Pn6A, Pn6B, Pn7F, Pn19A, Pn19F, and Pn23F) were shaped after a dose of PCV13 or PPSV23 in aged adults and how these initial responses influenced a PCV13 revaccination. Numerous humoral features were significantly induced by one dose of PCV13 compared to baseline, while one dose of PPSV23 showed an increase only in total IgG and IgG2 to serotype Pn3. Revaccination with PCV13 one year later showed a humoral response comparable with initial PCV13, but not with the initial PPSV23 dose; the latter group was resistant to expansion and several S. pneumoniae humoral features even contracted compared to baseline. These results highlight the importance of the initial vaccine platform for S. pneumoniae in aged adults.