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

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.