Review of pneumococcal conjugate vaccine in adults: implications on clinical development.

A literature review was conducted to determine if pneumococcal conjugate vaccines administered to healthy and immunocompromised adults, in comparison with the known efficacy in children, showed immunogenicity. Fifteen publications were retrieved. Clinical studies had been conducted using vaccines from different manufacturers, in different populations, using varied methodologies. No clear evidence of the superiority of the conjugate vaccine over the currently licensed polysaccharide vaccine emerged. Possible reasons for the lack of superiority and its implications on vaccine development are discussed.