Invasive Haemophilus influenzae infections in Germany after the introduction of routine childhood immunization, 2001-2016

Introduction Haemophilus influenzae (Hi) serotype b (Hib) vaccination was introduced in Germany in 1990. This study presents a comprehensive overview on the burden of invasive Hi infections for 2001-2016, including serotype-distribution and ampicillin resistance. Materials and Methods Nationwide data from statutory disease surveillance (2001-2016) were linked with laboratory surveillance data (2009-2016). Besides descriptive epidemiology, statistical analyses included multiple imputation to estimate secular trends. Results In 2001-2016, 4,044 invasive Hi infections were reported. Mean incidence was 3.0 per million inhabitants, higher in males (3.2 vs. 2.9 in females) and in age groups <1 year (15.2) and ≥80 years (15.5). Non-typeable Hi (NTHi) caused 81% (n=1,545) of cases in 2009-2016. Of capsulated cases, 69% were serotype f and 17% serotype b. Of Hib cases eligible for vaccination, 10% (3/29) were fully vaccinated. For 2009-2016, significant increasing trends were observed for NTHi and Hif infections in age groups <5 years and ≥60 years and for ampicillin resistance in NTHi. Conclusions This is one of the most comprehensive Hi data analyses since the introduction of Hib vaccines. NTHi and Hif cause an increasing disease burden among elderly patients and infants. Ampicillin resistance in NTHi must be considered in the treatment of invasive Hi infections.