Pneumococcal polysaccharide, immunogenicity

The 23-valent pneumococcal polysaccharide vaccine contains 23 serotypes that are responsible for causing more than 80% of invasive S. pneumoniae infections in adults. The vaccine includes those serotypes that are associated with drug resistance. Use of the vaccine will not prevent the development of antibiotic-resistant S. pneumoniae, but is likely to prevent infection from drug-resistant strains. The 23-valent pneumococcal polysaccharide vaccine has demonstrated good immunogenicity in adults, but an individual will not develop immunity to all 23 serotypes following vaccination.10... 

Each dose of pneumococcal vaccine contains 25 micrograms of polysaccharide immunogens. How many doses of the vaccine can be obtained with two grams of the polysaccharide immunogens ... 

The immunogenicity and safety of pneumococcal polysaccharide vaccine have been studied in renal allograft recipients, dialysis patients (19), children and adolescents with sickle-cell anemia (SED-11, 682) (SEDA-12, 277), people with diabetes mellitus (SED-11, 682), and children with nephrotic syndrome (20). When comparing the results with healthy persons there were no significant differences. 

S. pneumoniae has more than 80 sero-types. The current polysaccharide vaccine consists of 23 serotypes and covers about 87% of all pneumococcal diseases in the United States. Current vaccine development is based on conjugate technology and concentrates on the most prevalent 7—9 serotypes. Three multivalent vaccine candidates are in clinical trials. All are based on conjugating the polysaccharide to a T-dependent protein carrier. The results of phase I and II trials in infants have demonstrated the safety and immunogenicity (56—58) of these vaccines. Phase III trials to demonstrate efficacy against systematic diseases and otitis media are in progress and final approval of this vaccine for infant immunization will be by the year 2000. 

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