[Vaccines against Haemophilus influenzae B: present, past and future]

Haemophilus influenzae type b (Hinb) is the main etiologic agent of severe pediatric illnesses, such as meningitis, epiglottitis and pneumonia. Countries most affected by this pathogen are localized in the American, European and African continents. While this organism was originally isolated 100 years ago, the first field trial using a whole killed vaccine was performed until 1959. Since then, further controlled clinical trials have mainly been conducted in the North American and European continents. Under appropriate safety and efficacy evaluation tests performed by the Federal Drug Administration Agency (FDA), five vaccines were licensed: one single and four conjugated preparations. Worldwide and regional epidemiologic data concerning serious diseases produced by this organism have shown their outstanding impact in the public health of developed countries. Unfortunately, in developing countries similar epidemiological indexes are lacking for lethal and disabling diseases, such as meningitis. In order to decrease high morbidity and mortality rates of this meningeal disease and its neurological sequelae, immunoprophylactic preventive measures have been recommended. Furthermore, some risk factors of this infant illness can also be reduced. New strategies regarding conjugate Hib-vaccines are reviewed. Finally, promising virulence factors or self Hib-structures for the production of vaccines are suggested, such as outer membrane proteins (OMP), lipooligosaccharides, fimbriae or pili.