Pneumococcal conjugate vaccine.

Pneumococcal infections account for a significant proportion of bacterial infections in infants and children. The growing threat from pneumococci resistant to penicillin and other antimicrobials has led to increased pressure for the development of an effective vaccine. The only vaccine available until recently, a purified polysaccharide vaccine, is limited in that it fails to induce adequate and long-lasting immunity in infants under 2 years of age, the age group most at risk from this disease. Polysaccharide antigens conjugated to certain proteins induce effective immunity with a rapid response to subsequent infection or antigen challenge. The success of the protein-conjugated haemophilus influenzae vaccine supports the strategy of protein-conjugated polysaccharide vaccines. Currently, published trials of conjugated pneumococcal vaccines have shown the effectiveness and safety of these vaccines. Conjugate vaccines also provide protection against otitis media and may eliminate nasopharyngeal carriage of this organism. Widespread use of this vaccine is both cost effective and safe.