Comparison of pneumococcal conjugate polysaccharide and free polysaccharide vaccines in elderly adults: conjugate vaccine elicits improved antibacterial immune responses and immunological memory.

BACKGROUND: High functional antibody responses, establishment of immunologic memory, and unambiguous efficacy in infants suggest that an initial dose of conjugated pneumococcal polysaccharide (PnC) vaccine may be of value in a comprehensive adult immunization strategy. METHODS: We compared the immunogenicity and safety of 7-valent PnC vaccine (7vPnC) with that of 23-valent pneumococcal polysaccharide vaccine (PPV) in adults >/=70 years of age who had not been previously vaccinated with a pneumococcal vaccine. One year later, 7vPnC recipients received a booster dose of either 7vPnC (the 7vPnC/7vPnC group) or PPV (the 7vPnC/PPV group), and PPV recipients received a booster dose of 7vPnC (the PPV/7vPnC group). Immune responses were compared for each of the 7 serotypes common to both vaccines. RESULTS: Antipolysaccharide enzyme-linked immunosorbent assay antibody concentrations and opsonophagocytic assay titers to the initial dose of 7vPnC were significantly greater than those to the initial dose of PPV for 6 and 5 of 7 serotypes, respectively (P < .01 and P < .05, respectively). 7vPnC/7vPnC induced antibody responses that were similar to those after the first 7vPnC inoculation, and 7vPnC/PPV induced antibody responses that were similar to or greater than antibody responses after administration of PPV alone; PPV/7vPnC induced significantly lower antibacterial responses, compared with those induced by 7vPnC alone, for all serotypes (P < .05). CONCLUSION: In adults, an initial dose of 7vPnC is likely to elicit higher and potentially more effective levels of antipneumococcal antibodies than is PPV. In contrast with PPV, for which the induction of hyporesponsiveness was observed when used as a priming dose, 7vPnC elicits an immunological state that permits subsequent administration of 7vPnC or PPV to maintain functional antipolysaccharide antibody levels.

The safety, reactogenicity and immunogenicity of a 7-valent pneumococcal conjugate vaccine (7VPnC) concurrently administered with a combination DTaP-IPV-Hib vaccine.

To evaluate immune responses, safety and reactogenicity of the concomitant use of DTaP-IPV-Hib and the newly available 7-valent pneumococcal conjugate (7VPnC) vaccines when given as the primary immunization series in early infancy. A total of 231 healthy infants were enrolled at 11 German study centers and randomized to receive either 7VPnC plus DTaP-IPV-Hib vaccines concomitantly into opposite limbs at age 2, 3, 4 and 11-15 months (7VPnC group) or DTaP-IPV-Hib vaccine at the same ages plus a 7VPnC "catch-up vaccination" at ages 6, 7, 8 and 11-15 months (Control group). Blood samples were drawn before and 4 weeks after the first three vaccine doses and 4 weeks after the fourth dose. Local and general side effects (i.e. safety) were solicited by diary cards. Immune responses were determined by ELISA except for antibodies to polioviruses (neutralization assay). Post-dose 3, a significant antibody response against all seven pneumococcal vaccine-serotypes was observed in the 7VPnC group only. Post-dose 4 geometric mean concentrations (GMCs) were similar in both groups. GMCs for other vaccine antigens were comparable between groups except for diphtheria (higher in the 7VPnC group) and pertactin (lower in the 7VPnC group), although after three vaccine doses there was a 28-fold rise in GMCs from baseline. Both vaccines were generally well-tolerated although there were minor differences in the frequency of local reactions and somewhat more fever or drowsiness in the 7VPnC group. The use of DTaP-IPV-Hib and the 7VPnC vaccine was safe, well-tolerated and immunogenic when given concomitantly at age 2, 3 and 4 months or when given separately with 7VPnC as a catch-up vaccination at age 6, 7, 8 months and as a concomitant booster immunization at age 11-15 months.