Invasive pneumococcal disease in Scotland, 1999-2001: use of record linkage to explore associations between patients and disease in relation to future vaccination policy

A record linkage study was done to provide comprehensive data on the epidemiologic characteristics of invasive pneumococcal disease (IPD) in Scotland. The overall incidence of IPD was 11 cases/10(5) persons and 21 cases/10(5) persons <1 year of age, 51 cases/10(5) persons 1 year of age, 45 cases/10(5) elderly persons (age > or =65 years), 176-483 cases/10(5) persons with chronic medical conditions, and 562-2031 cases/10(5) persons with severe immunosuppression. The case-fatality rate was 11% among elderly persons and ranged from 3% to 13% among persons with underlying medical conditions. The most common pneumococcal serogroups associated with IPD were 14, 9, 6, 19, 23, 8, and 4. Serogroups included in the 23-valent polysaccharide vaccine caused the majority of cases of IPD. The proportion of IPD due to the 7-, 9-, and 11-valent conjugate vaccine serogroups was lower among older people and persons with underlying medical conditions.