BOX 1 Conjugate Technology for the Developing World—Issues and Potential Problems: S. Pneumoniae Vaccines

  • Incomplete serotype coverage

  • Variable immunogenicity

  • Possible limited effectiveness

  • Potential for ecologic replacement

  • High manufacturing costs

  • Quality control challenge

  • Difficult technology transfer

  • Complex delivery (multiple doses/injection)

SOURCE: Russell, 1994.

Meningococcal Vaccines14

Currently available vaccines against N. meningitides-caused meningitis are far from optimal, particularly with respect to the population most relevant to the CVI: children. The existing polysaccharide vaccines against serogroups A and C—the most prevalent types in the so-called meningitis belt—provide little or no protection in children under 18 months of age. In addition, the duration of protection of a single dose of Group A vaccine is less than 2 years in children 1 to 4 years of age. For these reasons, A/C polysaccharide vaccines are used in all U.S. military personnel, and many thousands of doses are used for epidemic control. Researchers have developed and are testing in humans a meningococcal A/C conjugate vaccine, which they hope will be immunogenic in infants.

The capsular polysaccharides of the group B meningococcus, which causes disease primarily outside of the meningitis belt, are poorly immunogenic in adults and children. One possible explanation is the group B polysaccharides’ similarity to sialic acid moieties on human tissue. Therefore, vaccine researchers have focused their efforts on alternative cell-surface antigens. These include the

14  

Unless otherwise noted, material in this section is based on presentations by Wendell Zollinger and Carl Frasch.



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