Indexed on: 25 Jul '09Published on: 25 Jul '09Published in: Expert review of vaccines
The introduction of a 7-valent pneumococcal conjugate vaccine (PCV-7) into the routine childhood vaccination schedule has been shown to be effective in preventing invasive pneumococcal disease (IPD), pneumonia, otitis media and meningitis in infants and young children as determined by epidemiological surveillance studies. There has been a rise in IPD due to nonvaccine serotypes; however, this rise is small compared with the overall reduction in IPD. Non-PCV-7 serotypes and vaccine-related serotypes, such as serotypes 1, 5, 7F, 6A and 19A, have also been reported to cause IPD in some parts of the world where morbidity and mortality from pneumococcal disease are higher. An investigational 13-valent pneumococcal conjugate vaccine (PCV-13) uses CRM(197) as a carrier, similar to the current PCV-7, and covers serotypes 1, 3, 5, 6A, 7F and 19A, in addition to the serotypes of PCV-7 (serotype 4, 6B, 9V, 14, 18C, 19F and 23F). PCV-13 is safe and well tolerated with other pediatric vaccines in infants according to clinical trials. IgG anticapsular polysaccharide-binding concentrations and opsonophagocytic assay responses are similar and noninferior between PCV-13 and PCV-7 and, according to immunogenicity studies, PCV-13 has more potential to protect against pneumococcal diseases with the additional six serotypes. With the addition of these new serotypes, it could be possible to cover potential pneumococcal serotypes causing IPD throughout the world. The cost of the vaccine, its length of duration, optimal scheduling, combination and boosting with PCV-7 are still unresolved issues. Assessment of the vaccine's effectiveness and efficacy following potential licensure will require carefully designed cohort and case-control studies that can assess the indirect effects of PCV-13.