Cross reactivity within pneumococcal serogroups 6 and 15 following adult vaccination with pneumococcal conjugate vaccine V116

Pneumococcal conjugate vaccines (PCVs) are designed to induce serotype-specific antibodies; however, antibodies raised against pneumococcal polysaccharides in the vaccine can also cross-react to other serotypes based on structural similarities. Cross-reactivity has been demonstrated for some licensed PCVs and is a worthy consideration to broaden protection against pneumococcal disease. This secondary analysis examined cross-reactive immune responses within serogroups 6 and 15 following vaccination with V116, an adult-specific PCV. Antibody levels were assessed across five phase 3 clinical studies at baseline and 30 days following vaccination. V116 elicits functional antibodies to vaccine serotypes 6A and 15C that result in cross-reactive antibodies to serotypes 6C and 15B, respectively, as assessed by opsonophagocytic activity responses from pre- to post-vaccination and IgG geometric mean concentrations. V116-induced antibodies demonstrate cross-reactivity to serotypes 6C and 15B, suggesting protective immune responses may be raised against these non-vaccine serotypes. V116 is a vaccine designed for adults to prevent bacterial infections caused by pneumococcus, such as pneumonia and meningitis. Following vaccination with V116, the body produces antibodies that help neutralize pneumococcus. As part of the clinical evaluation of V116, this study examined how antibodies generated by the vaccine cross-react with certain types of pneumococcus not contained in the vaccine. Immune responses were generated against pneumococcal types not present in the vaccine, suggesting V116 may provide protection against these pneumococcal types as well. These findings support the value of vaccination with V116 to prevent pneumococcal disease. Li, Platt et al. examine cross-reactivity of antibodies induced by the adult-specific pneumococcal conjugate vaccine V116 within serogroups 6 and 15. Antibodies demonstrated cross-reactivity to non-vaccine serotypes 6 C and 15B, suggesting broader coverage may be available beyond the 21 V116 serotypes following vaccination.