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Category: Bacterial Pathogenesis; Immunology
Immunogenicity and Safety in Adults, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555815820/9781555814083_Chap17-1.gif /docserver/preview/fulltext/10.1128/9781555815820/9781555814083_Chap17-2.gifAbstract:
During the past decade, a number of studies have evaluated the immunogenicity and safety of various pneumococcal conjugate vaccine (PCV) formulations in immunocompromised and immunocompetent adults. This chapter summarizes the findings from evaluations of PCVs in immunocompetent adults. Two early studies evaluated the immune response to monovalent PCV formulations by using radioimmunoassays, but since that time, all clinical studies of PCVs in immunocompetent adults have assessed the immunoglobulin G (IgG) antibody response by using enzyme-linked immunosorbent assays (ELISAs) and, in some cases, additional immunologic assays, such as the opsonophagocytic assay (OPA). Two studies were conducted among different populations and used different laboratories for the ELISA, which have been standardized to give similar results in different laboratories. The geometric mean concentrations (GMCs) are strikingly similar, suggesting that the administration of pneumococcal polysaccharide vaccine (PPSV) may induce hyporesponsiveness to PCV which persists for at least 5 years. This chapter defines a booster response simply as one involving significantly higher antibody levels in PCV-primed individuals than in unprimed individuals following the administration of the standard licensed dose of PPSV. PCVs are well tolerated in immunocompetent adults. The experience with PCV in adults as described in published reports is limited, and conclusions about the immunogenicity and safety of PCVs must be viewed as preliminary and subject to confirmation in larger, well controlled studies.
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ELISA-measured GMC of IgG antibodies following administration of a 0.5-ml dose of PCV7-CRM (7vPnC) to three groups of elderly adults defined by their previous exposure to PPSV (23vPS). The first group consisted of 110 pneumococcal-vaccine-naïve adults enrolled in the study by de Roux ( 7 ), the second group consisted of 78 participants in the de Roux study who received the PCV 1 year after the PPSV, and the third group consisted of 44 adults in the study by Jackson et al. who received the PCV 5 or more years after the PPSV ( 12 ). The GMCs following the PCV dose tended to be lower in the groups previously exposed to PPSV than in the pneumococcal-vaccine-naïve group.
ELISA-measured IgG response to PCV7-CRM at days 7, 14, 28, and 42 in 15 healthy young adults. Adapted from the Journal of Infectious Diseases ( 16 ) with permission from the publisher.
Serum IgG antibody responses to capsular types 6B, 14, 18C, 19F, and 23F in older adults after immunization with an investigational 5-valent oligosaccharide CRM PCV (CV) or the 23-valent PPSV (PV). Arrows indicate times of first and second vaccine injections. Closed circles, subjects immunized with the PCV at month 0 and the PPSV at month 6; open circles, subjects immunized with the PPSV at month 0 and a placebo at month 6; asterisks, significant difference in GMC between vaccine groups (P < 0.05). Reprinted from the Journal of Infectious Diseases ( 26 ) with permission from the publisher.
Characteristics of 15 polysaccharide-protein conjugate vaccine formulations evaluated in published clinical studies that included immunocompetent adults
Published results of clinical trials excluding dose-ranging studies comparing the ELISA-measured IgG response to PCV with the response to PPSV in immunocompetent adults
Results of dose-ranging studies of PCV7-CRM (Prevnar) comparing the ELISA-measured IgG responses to various PCV dosages with the response to PPSV in immunocompetent elderly adults
Results of dose-ranging studies of PCV7-CRM (Prevnar) comparing the OPA-measured responses to various PCV dosages with the response to PPSV in immunocompetent elderly adults
Antibody response in immunocompetent adults as measured by ELISA and OPA following first and second doses of PCV
ELISA-measured IgG response to PPSV challenge given at various intervals after PCV compared with the response to PPSV alone
Prevalence of fever and local signs and symptoms in elderly subjects following administration of PCV7-CRM a compared to those following administration of 23-PPSV