RESUMO
BACKGROUND: The pneumococcal vaccine, a nonconjugated vaccine, may be used to evaluate the integrity of the humoral immune system. Those patients with an inferior response to a nonconjugated vaccine may be vaccinated with a conjugated vaccine, which elicits both a B- and T-cell response. OBJECTIVE: We evaluated the immunogenicity of a conjugated vaccine in patients with inferior responses to a nonconjugated vaccine. METHODS: This was an institutional review board approved retrospective study that involved 22 patients with suspected specific antibody deficiency who received a nonconjugated vaccine, followed by a conjugated vaccine. Patients with an inferior response had <70% response in pneumococcal serotypes (1.3 µg/mL, with at least a two to fourfold increase), whereas protective responses were those with a >70% response. These patients were subsequently administered a conjugated vaccine at various time intervals (1-36 months), and titers were evaluated 4-6 weeks later. RESULTS: A protective response was found in 6 of 22 patients (average age, 62.2 years) after conjugated vaccine administration. Half of the responders were vaccinated <12 months after nonconjugated vaccine administration. The majority of the nonresponders (n = 16) received a conjugated vaccine <12 months after a nonconjugated vaccine. Of the nonresponders, 10 received a conjugated vaccine <12 months after a nonconjugated vaccine and did not mount a protective response. Other associated immunologic findings included hypogammaglobulinemia (n = 6), low immunoglobulin G1 (IgG1) levels (n = 5), and low IgG2 levels (n = 6). CONCLUSION: The majority of the patients with an inferior response to a nonconjugated vaccine also had an inferior response to a conjugated vaccine. Conjugated vaccine administration time did not affect the response rate. Analysis of the data demonstrated that patients with suspected specific antibody deficiency may not benefit from a conjugated vaccine, which suggested a defect that may affect more than pure antibody responses. Also, the majority of patients with IgG2 deficiency mounted an inadequate response to Pneumococcal 13-valent conjugate vaccine.