The burden of pneumococcal disease: the role of conjugate vaccines.

The pneumococcus remains a major cause of morbidity and mortality in both underdeveloped and developed countries. Although there are licensed, safe vaccines against invasive pneumococcal disease currently available in the US and Europe, several major dilemmas are apparent. First, the efficacy of these vaccines in high risk immunocompetent adults is only moderate, with limited or no immunogenicity in very high risk, immunocompromised adults. Secondly, efficacy of the vaccine against pneumococcal pneumonia in adults is controversial. Thirdly, the current vaccines are not efficacious in children < 2 years of age, which is problematic given the high rate of invasive disease among this age group. The solution to these dilemmas may lie in the development of protein conjugate-polysaccharide vaccines. This paper briefly reviews the role of conjugate pneumococcal vaccines.