Immunogenicity of pneumococcal vaccination of patients with cochlear implants

Abstract

Background. Pneumococcal meningitis is a rare but potentially fatal complication of cochlear implantation. Methods. A prospective study was conducted of the immunogenicity of pneumococcal vaccination in 174 patients with cochlear implants (CIs). The cohort was divided into groups of patients with impaired hearing due to meningitis (P1), cranial malformations (P2), or an unknown cause (P3) and was stratified by age as follows: <2 years (A1), 2-5 years (A2), and >5 years (A3). We determined immunoglobulin (Ig) levels for IgG subclasses 1-4 and serum concentrations of antibodies against pneumococci before and 4-6 weeks after vaccination. Group A1 received the 7-valent pneumococcal conjugate vaccine (PCV-7), group A2 received PCV-7 or the 23-valent pneumococcal polysaccharide vaccine (PPV-23), and group A 3 received PPV-23. Results. IgG, IgM, and IgG1 levels were significantly lower in group P1, compared with the other patient groups and with historic data for healthy control subjects, suggesting a decreased antibody response. Group P1 had lower levels of pneumococcal antibodies, compared with groups P2 and P3 before vaccination (P < .05, pneumococcal serotypes 4 and 9V). Irrespective of the underlying condition, all patients showed a sufficient antibody response after 1 dose of vaccine. In children 2-5 years of age, PCV-7 was significantly more immunogenic than PPV-23. Conclusions. PCV-7 should be administered to all CI recipients younger than 6 years and older than 6 years who are at an increased risk for bacterial meningitis. CI recipients with a history of bacterial meningitis should undergo immunological evaluation.