The burden of invasive
pneumococcal disease in young children decreased dramatically following introduction of the 7-valent pneumococcal
conjugate vaccine (PCV7). The epidemiology of S. pneumoniae now reflects
infections caused by serotypes not included in PCV7. Recently introduced higher valency
pneumococcal vaccines target the residual burden of invasive and non-invasive
infections, including those caused by serotypes not included in PCV7. This review is based on presentations made at the European Society of Pediatric
Infectious Diseases in June 2011.
DISCUSSION: Surveillance data show increased circulation of the non-PCV7
vaccine serotypes 1, 3, 6A, 6C, 7 F and 19A in countries with routine vaccination. Preliminary evidence suggests that broadened serotype coverage offered by higher valency
vaccines may be having an effect on invasive disease caused by some of those serotypes, including 19A, 7 F and 6C. Aetiology of community acquired
pneumonia remains a difficult clinical diagnosis. However, recent reports indicate that pneumococcal vaccination has reduced hospitalisations of children for
vaccine serotype
pneumonia. Variations in serotype circulation and occurrence of complicated and non-complicated
pneumonia caused by non-PCV7 serotypes highlight the potential of higher valency
vaccines to decrease the remaining burden. PCVs reduce nasopharyngeal carriage and acute
otitis media (AOM) caused by
vaccine serotypes. Recent investigations of the interaction between S. pneumoniae and non-typeable H. influenzae suggest that considerable reduction in severe, complicated AOM
infections may be achieved by prevention of early pneumococcal carriage and AOM
infections. Extension of the
vaccine serotype spectrum beyond PCV7 may provide additional benefit in preventing the evolution of AOM. The direct and indirect costs associated with
pneumococcal disease are high, thus herd protection and
infections caused by non-
vaccine serotypes both have strong effects on the cost effectiveness of pneumococcal vaccination. Recent evaluations highlight the public health significance of indirect benefits, prevention of
pneumonia and AOM and coverage of non-PCV7 serotypes by higher valency
vaccines.
SUMMARY: Routine vaccination has greatly reduced the burden of
pneumococcal diseases in children. The pneumococcal serotypes present in the 7-valent
vaccine have greatly diminished among disease isolates. The prevalence of some non-
vaccine serotypes (e.g. 1, 7 F and 19A) has increased.
Pneumococcal vaccines with broadened serotype coverage are likely to continue decreasing the burden of invasive disease, and community acquired
pneumonia in children. Further reductions in pneumococcal carriage and increased prevention of early AOM
infections may prevent the evolution of severe, complicated AOM. Evaluation of the public health benefits of pneumococcal
conjugate vaccines should include consideration of non-invasive
pneumococcal infections, indirect effects of vaccination and broadened serotype coverage.