Prospects for pneumococcal vaccination in African children

Streptococcus pneumoniae (pneumococcus) remains a major cause of morbidity and mortality in both developed and undeveloped countries. Accurate disease burden estimates for developing countries and Africa in particular, where diagnostic facilities are less adequate and a disease surveillance system v irtually non-existent, is difficult. However, from conservative estimates, the pneumococcus is probably responsible for at least 1 million of the 4 mi llion deaths that occur from acute lower respiratory infections in children aged less than 5 years. The global burden of disease has been accentuated by the rising menace of multi-drug resistant strains, which defy geographic and racial borders. Thus, now more than ever before, there is an urgent ne ed to identify and implement preventive measures to avert this problem. The currently licensed pneumococcal polysaccharide vaccine, comprises 23 capsu lar polysaccharides of the pneumococcus, many of which are poorly immunogen ic in the very vulnerable age group of under-fives. A possible solution to the problem of poor immunogenicity is to use a protein/polysaccharide conju gate Vaccine similar to that recently introduced successfully for Haemophil us influenzae type b (Hib) and using this approach, several workers have re ported promising results from safety and immunogenicity studies. However, u nlike Hib, the development of conjugate vaccine against pneumococcal diseas e is complicated by the existence of more serotypes than can be feasibly in corporated in a single conjugate Vaccine formulation. Whilst this challenge has been taken on by some vaccine manufacturers, novel approaches such as the identification or construction of protective protein antigen, common to all clinically important strains are being explored. Novel application of the pneumococcal polysaccharide vaccines in pregnancy for protection of dis ease in early infancy is an approach that has not been evaluated. For maxim um impact, the ultimate vaccine formulation should be affordable and availa ble to resource poor countries where the burden of disease is highest. Esta blishing disease surveillance systems in such countries now will greatly fa cilitate the introduction of the vaccines. (C) 2000 Elsevier Science B.V. A ll rights reserved.