Pneumococcal immunization in immunocompromised hosts: where do we stand?

Abstract

Immunocompromised patients are all at risk of invasive pneumococcal disease, of different degrees and timings. However, considerable progress in pneumococcal immunization over the last 30 years should benefit these patients. The 23-valent polysaccharide vaccine has been widely evaluated in these populations, but due to its low immunogenicity, its efficacy is sub-optimal, or even low. The principle of the conjugate vaccine is that, through the protein conjugation with the polysaccharide, the vaccine becomes more immunogenic, T-cell dependent, and thus providing a better early response and a boost effect. The 7-valent conjugate vaccine has been the first one to be evaluated in different immunocompromised populations. We review here the efficacy and safety of the different antipneumococcal vaccines in cancer, transplant and HIV-positive patients and propose a critical appraisal of the current guidelines.

Keywords::

• antipneumococcal vaccine
• conjugate vaccine
• immunesuppression
• invasive pneumococcal infection
• polysaccharide vaccine

Financial & competing interests disclosure

C Cordonnier has been a consultant for Wyeth and Pfizer and got research grants from Pfizer for her department. D Engelhard, D Averbuch and S Maury have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscripts. This includes employments, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents or pending, or royalties. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Immunocompromised patients have a 10- to 50-fold risk of invasive pneumococcal disease when compared to healthy patients of the same age range.

• Among immunocompromised patients, a schedule with an initial 13-valent pneumococcal conjugate vaccine (PCV) followed by the 23-valent polysaccharide vaccine (PPV23) seems logical for induction of anamnestic immune responses by PCV as well as for expanding serotype coverage by PPV23.

• After allogeneic hematopoietic stem cell transplantation, the response to PPV23 is poor at least for 6–12 months and even still longer in case of graft-versus-host disease. The conjugate vaccine is mostly immunogenic from 3 months after transplant.

• In solid organ transplant candidates, pretransplant pneumococcal vaccination is recommended, using one dose of conjugate followed by one dose of PPV23. However, the titers of antipneumococcal antibodies drop in most cases following the transplantation, and the benefit of revaccination 3–6 months after transplant should be explored.

• In HIV-infected individuals, although antiretroviral therapy reduces their risk of invasive pneumococcal disease, the risk still remains 20- to 40-fold greater as compared with age-matched general population. In infants, antiretroviral treatment and higher CD4+ cells enhance the antibody responses to PCV. In adults, there are conflicting data about the variables that influence the response to PPV23. PCV results in higher antibody concentration than PPV23, for certain serotypes.