Epidemiology of invasive pneumococcal infections in children in Finland.

OBJECTIVE

To study the epidemiologic characteristics of invasive infections in children caused by Streptococcus pneumoniae to provide background data for vaccination programs.

DESIGN

A nationwide laboratory-based prospective surveillance of all invasive pneumococcal infections in children during 1985 through 1989.

SETTING

A network of all microbiologic laboratories and pediatric wards in Finland.

PATIENTS

Children aged 0 to 15 years who were admitted to a hospital with S pneumoniae isolated from blood, cerebrospinal fluid, or deep aspirate sample.

RESULTS

Four hundred fifty-two invasive pneumococcal infections were diagnosed in 1985 through 1989. The annual incidence rate was 8.9 per 100,000 children less than 16 years of age (24.2 per 100,000 among children less than 5 years of age and 45.3 per 100,000 among those less than 2 years of age). The most common clinical entities were bacteremia without focus (310 cases), pneumonia (66 cases), and meningitis (51 cases), with other focal infections seen in 25 cases. The pneumococcal groups/types 14, 6, 19, 7, 18, and 23 comprised 78% of all invasive infections.

CONCLUSIONS

Streptococcus pneumoniae is a common cause of invasive infections in children in Finland. A pneumococcal conjugate vaccine containing the six most common groups/types could prevent up to 70% of invasive pneumococcal infections of children in Finland if fully protective in infancy.