Effects of a large-scale introduction of the pneumococcal polysaccharide vaccine among elderly persons in Stockholm, Sweden.

In October 1998 Stockholm County launched a 3-year vaccination campaign with the 23-valent pneumococcal polysaccharide vaccine (PPV-23) directed towards all elderly persons. We analysed the impact of this campaign on the incidence and serotype distribution of invasive pneumococcal disease (IPD) in Stockholm County, where the vaccine coverage was 36%, as compared to Skåne County, where no vaccination campaign was performed. The incidence of vaccine-type IPD in Stockholm declined significantly during the study period (1997-2001) in elderly persons, from 50 to 28.9/100,000, but not in other age groups in Stockholm, nor in any age group in Skåne.