Immunogenicity of the 10-Valent Pneumococcal Non-typeable Haemophilus influenzae Protein D Conjugate Vaccine (PHiD-CV) Compared to the Licensed 7vCRM Vaccine

Background: The immunogenicity of the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV) was assessed and compared with the 7-valent pneumococcal conjugate vaccine (7vCRM). Methods: Healthy subjects (1650) were randomized to be vaccinated with 3 doses of PHiD-CV or 7vCRM (Prevenar(TM)/Prevnar(TM) at 2-3-4 months of age and a fourth booster dose at 12-18 months. Serotype-specific pneumococcal responses (GlaxoSmithKline's ELISA with 22F-inhibition) and opsonophagocytic activity (OPA) were measured I month after primary and booster vaccinations. Results: The primary objective to demonstrate noninferiority of PHiD-CV versus 7vCRM (in terms of percentage of subjects with antibody concentration >= 0.2 mu g/mL) for at least 7 of the 10 vaccine serotypes was reached as noninferiority was demonstrated for 8 serotypes. Although, noninferiority could not be demonstrated for ELISA responses against serotypes 6B and 23F, a post-hoc analysis of the percentage of subjects with OPA titers >= 8 suggested noninferiority for the 7 serotypes common to both vaccines including 613 and 23F. Priming of the immune system against all vaccine serotypes was confirmed by robust increases in ELISA antibody levels (similar to 6.0-17 fold) and OPA titers (similar to 8-93 fold) after a fourth consecutive dose of PHiD-CV. Conclusions: PHiD-CV induces ELISA and functional OPA antibodies for all vaccine serotypes after primary vaccination and is noninferior to 7vCRM in terms of ELISA and/or OPA threshold responses. Effective printing is further indicated by robust booster responses.