Background: Pneumococcal conjugate vaccines (PCV) are emerging as one of the most promising means to prevent pediatric disease. The 7-valent PCV (PCV-7) has been extensively evaluated in clinical trials, and recent evidence from the introduction of PCV-7 through national immunization programs has demonstrated impact on pneumococcal disease.
Methods: Clinical trials have shown PCV-7 to be effective against the more severe forms of pneumococcal infections: pneumonia and invasive pneumococcal disease (IPD), as well as overall child mortality. A review shows the tremendous impact PCV-7 has had to date, and the potential further benefits of the emerging multi-valent vaccines.
Results: Since its introduction, the PCV-7 has substantially reduced the incidence of IPD, hospital admissions due to pneumonia and acute otitis media in numerous, mostly high income, low-disease burden countries. The reductions in IPD and pneumonia have also been observed among unvaccinated age groups in countries with routine use of PCV-7, demonstrating that PCV-7 provides herd immunity. Some settings observed an increase in rate of nonvaccine serotype IPD, yet rates of overall and vaccine-serotype IPD show marked reductions post-PCV-7 introduction. Limited data are available on the impact of PCV-7 in lower income countries. The available data from efficacy trials from The Gambia and South Africa suggest that PCV-7 will have substantial impact on reducing pneumococcal disease.
Conclusion: PCV-7 has shown dramatic reduction in disease and mortality rates in the countries in which it has been introduced. The newly introduced 10-valent and 13-valent pneumococcal vaccines are expected to have substantial disease impact, but monitoring is essential to determine their true impact and sustain further introduction of pneumococcal conjugate vaccines.