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Background Invasive pneumococcal disease (IPD) in people ≥60 years old is on the rise in Germany. There has been a recommendation for pneumococcal vaccination in this age group since 1998. Methods We determined the vaccination status of people ≥60 years old with IPD in Germany. We assessed vaccine effectiveness (VE) of the recommended 23-valent polysaccharide vaccine (PPV23) against IPD using the indirect cohort method. Results The rate of pneumococcal vaccination in older adults with IPD is low, 26%, with only 16% of people receiving a pneumococcal vaccine within five years of the IPD episode. Age- and gender- adjusted vaccine effectiveness (VE) for PPV23 was 37% (95% confidence interval 12% - 55%). For people vaccinated with PPV23 less than two years prior to IPD, VE was -20% (-131% - 34%), between two and four years prior to IPD, VE was 56% (20% - 76%), and 47% (17% - 63%) for those vaccinated ≥5 five years ago. Excluding serotype 3, overall VE for the remaining serotypes in PPV23 was 63% (49% - 74%). For people receiving PPV23 within the past two years, VE against all serotypes except 3 was 49% (12% - 71%); for people vaccinated between two and four years prior to IPD 66% (37% - 82%); for those vaccinated ≥five years ago, 69% (50% - 81%). VE of PPV23 against serotype 3 IPD only was -110% (-198% - -47%). Conclusions To reduce IPD in older adults in Germany, we must increase the rate of pneumococcal vaccine uptake. For 22/23 serotypes, PPV23 was effective. Serotype 3 remains a major problem. Funding This work was supported by an investigator-initiated research grant from Pfizer.

The etiological diagnosis of infections caused by Streptococcus pneumoniae has been expanded by non-culture methods, including the detection of pneumococcal DNA in biological samples and the identification of C polysaccharide in urine. The basis for these methods and their use and limitations in the recognition of infections of pneumococcal etiology are reviewed. The usefulness and applicability of traditional tests used for the identification of S. pneumoniae and the current and future usefulness of MALDI-TOF are discussed. The term clone is frequently used in molecular epidemiology, but it is used with different meanings by different authors. We discuss the terms clone, strain and isolate in the context of molecular epidemiology and of the increasing realization of the importance of lateral gene transfer in bacterial pathogen evolution. Of the multiple typing methods used to characterize pneumococci, serotyping, pulsed-field gel electrophoresis and multilocus sequence typing have had the widest acceptance and use. We discuss the major findings regarding disease epidemiology, population biology, and the impact of vaccination on pneumococci afforded by these methods. The advent of whole genome sequencing technologies has the potential to bring new insights onto pneumococcal population biology, evolution and epidemiology. Their impact on our current views and on key concepts in molecular epidemiology are presented.