Childhood PCV vaccination was generally recommended in Germany in 2006. Apart from a strong direct effect, herd protection effects among non-vaccinated children and adults were observed.
IPD in adults in Germany has been monitored since 1992. Isolates were serotyped using the Neufeld Quellung reaction.
Prior to introduction of PCVs in infants, 45% of IPD serotypes found among adults were PCV7 types and 70% were PCV13 types. After the start of childhood vaccination, these percentages gradually reduced to 5% and 30% and remained stable in the past five seasons. In 2018-2019, prevalences were of serotypes 3, 4, 19F and 19A were 20.3%, 2.1%, 3.7% and 1.5% respectively. The prevalence of serotype 3 has reached its highest point ever since the introduction of PCVs. Among non-PCV13 types, serotypes 8 (14.0%), 22F (7.2%), 9N (6.4) and 12F (5.0%) were most prevalent. New PCV formulations would cover 38.7% (PCV15) and 65.2% (PCV20).
The herd protection effect of PCVs among adults has reached its limit. No herd protection effect was observed for serotype 3. The data implicate circulation of PCV13 serotypes among adults, which might only be interrupted by direct vaccination.