Progress towards meningitis prevention in the conjugate vaccines era.

Acute bacterial meningitis is an important cause of morbidity and mortality among children less than five years old, Haemophilus influenzae, Streptococcus pneumoniae and Neisseria meningitidis being the most important agents of bacterial meningitis in developing countries. The development of the conjugate vaccines in the beginning of the 90's, especially type b H. influenzae (Hib), and more recently the heptavalent pneumococcal and the serogroup C meningococcal vaccines, have contributed directly to changes in the epidemiological profile of these invasive diseases (direct effect) and of their carriage status (indirect effect). We review the impact of the Hib conjugate vaccine in Latin American countries, where this vaccine has been implemented, and the potential of pneumococcal and meningococcal conjugate vaccines for the reduction of meningitis worldwide. We also address constraints for the development and delivery of these vaccines and review new candidate state-of-the-art vaccines. The greatest challenge, undoubtedly, is to implement these vaccines worldwide, especially in the developing regions.