Use of pneumococcal polysaccharide vaccine in children: What is the evidence?

Purpose of review: Pneumococcal glycoconjugate vaccines (PCVs) are now widely used in infant immunization schedules. These vaccines are also recommended for those at increased risk of pneumococcal infection and to provide optimal serotype coverage to those at increased risk of disease. The 23-valent polysaccharide vaccine (PPV23) is often advised from the second birthday to provide broader serotype coverage. The use of pneumococcal polysaccharide vaccines (PPVs) has in recent years become a topic of much debate, especially for use in children. Recent findings: Although no effect of PPV23 on carriage has been reported, some protection against invasive pneumococcal disease (IPD) is possible. There is a theoretical risk of memory B-cell depletion to PCV serotypes following PPV23 vaccination, even in PCV-primed children, but the clinical significance is currently unknown. This risk is increased by PPV23 revaccination. Summary: Whether the immune response to PPV23, non-PCV13 serotypes is sufficient to confer clinical benefit to at-risk children depends on their age, underlying disease and the immunogenicity of individual serotypes. Given the theoretical risk of memory B-cell depletion following PPV23 vaccination, it is not clear how best to maintain protection in those at-risk children who remain susceptible to IPD.