Safety and Immunogenicity of Heptavalent Pneumococcal Vaccine Conjugated to CRM197 Among Infants With Sickle Cell Disease

Abstract

Infants with SCD respond to 7VPnC vaccine with antibody concentrations that are at least as high as infants without SCD. Infants immunized with 7VPnC vaccine at 2, 4, and 6 months of age developed antibody concentrations in the same range as those achieved among infants without SCD enrolled in a large trial that demonstrated vaccine efficacy against invasive disease. Significant rises were seen in antibody concentrations to all 7VPnC serotypes after the PS-23 booster in children receiving schedule A or B.

Priming of Immunological Memory by Pneumococcal Conjugate Vaccine in Children Unresponsive to 23-Valent Polysaccharide Pneumococcal Vaccine

“…As we know from Haemophilus influenzae, conjugate vaccine efficacy is also determined by differences in the kinetics of immune response (17). Demonstration of B-cell memory has largely been based on a rapid and strong antibody response to a dose of plain polysaccharide vaccine after priming with a conjugate vaccine (32,33,54). There are only limited data on the kinetics of immunological memory in high-risk groups.…”

Economic impact of pneumococcal conjugate vaccination in Brazil, Chile, and Uruguay

“…Effects on lengthened hospital stay due to pneumococcal disease were also not considered. Likewise, the costs of adverse events associated with vaccination were not included because vaccine trial data suggest the safety of the vaccine to be equivalent to that of a placebo (4,(18)(19)(20)(21)(22)(23)(24). Nor does this study include potential indirect effects such as herd immunity because of the absence of burden of disease estimates for older children and adults in the studied countries.…”

Serotype-Specific and Age-Dependent Generation of Pneumococcal Polysaccharide-Specific Memory B-Cell and Antibody Responses to Immunization with a Pneumococcal Conjugate Vaccine

“…Toddlers immunized at 2, 4, and 6 months of age generate immunoglobulin G (IgG) antibody responses to Pnc7 (16), but the serum antibody wanes rapidly, with some serotype-specific antibody levels falling below the protective threshold within a matter of months (47,64). Similarly, in early infancy antibody wanes rapidly after immunization with other glycoconjugate vaccines, such as the Haemophilus influenzae type b (30) and serogroup C Neisseria meningitidis glycoconjugate vaccines (68), and there is a corresponding loss of vaccine effectiveness (56,70).…”

“…Children between 12 months and 2 years of age at the time that Pnc7 was introduced were included in a single-dose catch-up campaign. However, at 12 months of age, a single dose of Pnc7 may not be sufficient to induce protective levels (a protective level has been variously described as Ͼ0.2 g/ml or as 0.35 g/ml or 1.0 g/ml [4,27]) of antibodies to all seven serotypes included in the current vaccine (47), and there is little information about the persistence of antibody after this single-dose priming regimen and the subsequent memory responses.…”