The Impact of 7-valent Pneumococcal Conjugate Vaccine on Invasive Pneumococcal Disease: A Literature Review

Streptococcus pneumoniae can cause invasive pneumococcal diseases (IPD), such as bacteremic pneumonia, bacteremia, meningitis, and sepsis, and non-IPDs, such as otitis media, nonbacteremic pneumonia, and upper respiratory tract infections. It was estimated in 2000 that, worldwide, S. pneumoniae was responsible for 826,000 deaths annually in children aged between 1 month and 5 years. A 7-valent pneumococcal conjugate vaccine (PCV7) was licensed in 2000 in the USA and in 2001 in Europe. A literature search was performed in PubMed to identify studies assessing the impact of routine childhood PCV7 vaccination on pneumococcal morbidity and mortality. Here, the impact on IPD is reported. A total of 37 articles reporting impact data on IPD were included in this review: four from Australia, 17 from western Europe, and 16 from North America. In vaccine-eligible children in the postvaccination period, a reduction ranging from 39.9% in Spain to 99.1% in the USA in vaccine-type (VT) IPD incidence, compared with the prevaccination period, was reported in 18 studies. All but one of the 30 studies assessing the impact of PCV7 on all-type IPD reported a reduction ranging from 1.7% in Spain to 76.3% in Australia. In addition, the majority of studies reported reductions in VT and all-type IPD incidence in age groups that were not vaccine eligible. The results from this review illustrate that PCV7 has had a significant impact on IPD across all ages through its use in pediatric immunization programs. With the introduction of 13-valent pneumococcal conjugate vaccine (PCV13) further reductions in the incidence of IPD due to the six additional serotypes included, as well as continued protection against IPD due to PCV7 serotypes may be expected. Robust surveillance systems are essential for the evaluation of the impact of PCV13 on all-type IPD and for monitoring the evolution of non-VT IPD.