The burden of pneumococcal disease among adults in developed and developing countries: what is and is not known

The burden of pneumococcal disease among adults in developed countries is n either widely known nor appreciated. The incidence of pneumococcal pneumoni a is uncertain because a precise diagnosis cannot be obtained for most pati ents. Population-based data on invasive pneumococcal disease (e.g., bactera emia and meningitis) suggest an annual incidence in all developed countries of greater than or equal to 15-20 cases per 100,000 persons of all ages an d greater than or equal to 50 cases per 100,000 elderly adults (greater tha n or equal to 65 years). In developing countries there are no population-ba sed data on the burden of pneumococcal disease among adults. Studies of hig h risk groups, hospital-based studies, vaccine efficacy trials, extrapolati ons from surveillance of "native populations" in developed countries, and d emographic studies in developing regions all suggest a high burden of disea se. The broad variation in these estimates, however, indicates that better studies are needed. Increased use of pneumococcal vaccines among adults in all countries will depend on better scientific and public understanding of the burden of pneumococcal disease. In developing countries, intensive comm unity-based studies of the impact of pneumococcal disease, or, alternativel y, a "vaccine probe" approach, in which a population is vaccinated and the reduction in pneumonia is compared with that in a control population, could give more accurate estimates of the burden of disease and of the potential effectiveness of pneumococcal vaccination among adults. (C) 1999 Elsevier Science Ltd. All rights reserved.