Despite PCV7 Results, Vigilance Needed

In a study that was funded in part by Wyeth et al. of Kaiser Permanente, Oakland, Calif., found that the herd immunity conferred by individuals vaccinated with PCV7 resulted in significant savings in cost per life-year saved during the first 5 years following introduction of the vaccine.

However, they acknowledged, “if serotype replacement increases over time, it is possible that the efficacy of the vaccine—both for the vaccinated and nonvaccinated populations—could decline in the future” (Pediatr. Infect. Dis. J. 2006;25:494–501).

Current efforts to develop new multivalent pneumococcal conjugate vaccines will pay off in the long run. As we turn our attention to the next phase of development, we also must keep in mind and prioritize the needs in the developing world.

According to the World Health Organization, as many as 1 million children under 5 years of age die every year of pneumococcal pneumonia, meningitis, and sepsis. In populations with high child mortality rates, pneumonia is the leading infectious cause of mortality, accounting for about 20%–25% of all deaths in children.

Clinical trials now underway in Africa and elsewhere are utilizing conjugate pneumococcal vaccines containing between 7 and 13 serotypes. While serotype replacement could eventually occur in the developing world as well, the immediate impact in reducing disease and death would be enormous and undeniably worthwhile.

Phase III studies are ongoing with one prototype that contains 13 serotypes including 19A, 1, 3, 5, 6A, and 7V. Investigators estimate that in the United States, the 13-valent vaccine will cover around 60% of the remaining disease in children and expand coverage for strains prevalent in developing countries.

Despite the success of conjugate pneumococcal vaccine, it is clear that it will not be associated with the type of triumph we achieved with the Hib vaccine.

For the near future at least, we will need to remain vigilant when evaluating febrile children, understanding the clinical setting in which pneumococcal infection may occur. As the epidemiology of pneumococcal infection evolves, it is important for clinicians to continue to stay abreast of data regarding disease incidence, emerging serotypes, bacterial resistance, and future advances.