Pneumococcal conjugated vaccines: impact of PCV-7 and new achievements in the postvaccine era

Abstract

Pneumococcal disease is a major health problem worldwide. Large, rapid declines in overall invasive pneumococcal disease and mucosal disease in children, reductions in vaccine-type disease in unvaccinated children and adults (indirect effects) and significant drops in antibiotic-resistant infections were observed after the introduction of a safe, available and immunogenic seven-valent pneumococcal vaccine. The determination of vaccine efficacy is a complex process, which includes efficacy, immunogenicity, safety, cross-reactivity, indirect effects and substantial geographic variation in serotype coverage. In this report, we perform an overview of the literature on current, investigational and potential candidate pneumococcal conjugated vaccines (PCVs). Every country should have its own strong and sustained surveillance system implemented to monitor the effects of vaccination on the frequency of vaccine and nonvaccine serotypes for invasive or mucosal disease, nasopharyngeal carriage and the indirect effects before and after introduction of PCV. New PCVs (PHiD-CV and PCV-13) may provide even greater coverage worldwide, especially in developing countries. Vaccine experts' efforts are currently focused on developing alternative vaccine strategies against pneumococcal infections, especially the development of vaccines based on pneumococcal proteins.

Determining the Optimal Pneumococcal Vaccination Strategy for Adults

“…27,28 In addition, in children, PCV7 appears to result in signifi cant protection against nonbacteremic pneumococcal pneumonia and acute otitis media due to S pneumoniae , something not seen with the PPV23. 11 Finally, because of decreased nasopharyngeal carriage of pneumococcus in children after the release of PCV7, rates of invasive pneumococcal disease in adults also declined after PCV7 was released, 28 consistent with a herd-protective effect.…”

“…For those who wish more detailed information about any of the various pneumococcal vaccines, several excellent reviews are available. 4,8,[10][11][12] Determining Vaccine Efficacy…”

Nanogel-Based PspA Intranasal Vaccine Prevents Invasive Disease and Nasal Colonization by Streptococcus pneumoniae

“…T he use of polysaccharide-based injectable multivalent pneumococcal conjugate vaccines (PCV7, -10, and -13) has diminished the number of fatal infections due to pneumococci expressing the particular polysaccharides present in the vaccine (1)(2)(3). However, Streptococcus pneumoniae remains a problematic pathogen (4,5) because of the large number of different capsular polysaccharides associated with virulent disease in humans.…”

6th World Congress of the World Society for Pediatric Infectious Diseases (WSPID)

“…In February 2000, the US FDA licensed a 7-valent conjugate vaccine (PCV-7; Prevnar ® , Prevenar ® [Wyeth Pharmaceuticals, PA, USA]) containing seven pneumococcal polysaccharides (4, 6B, 9V, 14, 18C, 19F and 23F) conjugated to a nontoxic diphtheria toxin variant carrier protein, cross-reacting material (CRM)197 [38]. PCV-7 was introduced into national immunizations programs with different schedules in nearly 40 countries worldwide, and during WSPID, data on pneumo coccal seroepidemiology in the post-PCV-7 era and recent study results about new PCVs (PHiD-CV and PCV-13) were presented.…”

“…Serogroup B was predominant (63%) followed by C (31%), Y and W135 (2.8% each), but the global data presented a bias because more than 60% of the cases came from Brazil. Looking at data from individual countries, it is remarkable that serogroup C increased dramatically in Brazil 38.9% in 2008. The changes in the prevalence of serogroups B and C, the worrisome increase of serogroup W135, the high frequency of penicillin-nonsusceptible strains and the emergence of resistance to fluorquinolones, highlight the epidemiological relevance of the resistant strains.…”