Mechanisms of human immunity to polysaccharide encapsulated bacteria and the
development and testing of the currently available purified polysaccharide bacterial
vaccines are reviewed. These vaccines appear to be poorly immunogenic in infants under
the age of two years—those at greatest risk for infection. In an effort to understand the poor
responses of infants, the human immune response to polysaccharide antigens was
characterized in more detail. Using pneumococcal polysaccharide type 3 as an example, it …