Epidemiology of invasive pneumococcal disease in urban New South Wales, 1997-1999.

ABSTRACT

OBJECTIVES: To describe the serotypes, incidence and morbidity of invasive pneumococcal disease in urban New South Wales. DESIGN: Prospective laboratory surveillance. SETTING: Microbiology laboratories and hospitals in the Sydney, Hunter and Illawarra Statistical Divisions of NSW, June 1997 to May 1999. RESULTS: 1270 cases were identified in two years. Incidence of disease was highest in those aged < 2 years (96.4 per 100,000; 95% CI, 83.7-107.9) and > or = 85 years (100.1 per 100,000; 95% CI, 81.8-121.3). Incidence of disease increased significantly from the age of 60 years, compared with low rates in those aged 5-59 years. Underlying diseases predisposing to pneumococcal infection increased with age, from 4% (< 2 years) to 60% (> or = 65 years). A seven-valent conjugate vaccine would have covered 84.8% of serotypes in those aged 0-14 years, falling to 69% in those > or = 15 years. Penicillin resistance was significantly higher in the < 5 years group (19.0%) than in older people (14.6%). CONCLUSIONS: Incidence of invasive pneumococcal disease was higher in this study using active surveillance than in previous Australian studies. An effective sevenvalent conjugate pneumococcal vaccine could prevent more than 80% of cases in children aged < 5 years.