Ladhani S, Slack MPE, Heath PT, Von Gottberg A, Chandra M, Ramsay ME, McIntyre P, Gilbert L, Hogg G, Strauss R, Heuberger S, Hanquet G, Crokaert F, Krizova P, Lebedova V, Mølbak K, Christensen JJ, Kutsar K, Joks U, Herva E, Kaijalainen T, Leinonen M, Ruutu P, Lepoutre A, Dabernat H, Siedler Aet al. (2010): Invasive Haemophilus influenzae disease, Europe, 1996-2006
Emerg. Infect. Dis. 16 (3): 455-463.

An international collaboration was established in 1996 to monitor the impact of routine Haemophilus influenzae type b (Hib) vaccination on invasive H. influenzae disease; 14 countries routinely serotype all clinical isolates. Of the 10,081 invasive H. influenzae infections reported during 1996-2006, 4,466 (44%, incidence 0.28 infections/100,000 population) were due to noncapsulated H. influenzae (ncHi); 2,836 (28%, 0.15/100,000), to Hib; and 690 (7%, 0.036/100,000), to non-b encapsulated H. influenzae. Invasive ncHi infections occurred in older persons more often than Hib (median age 58 years vs. 5 years, p<0.0001) and were associated with higher case-fatality ratios (12% vs. 4%, p<0.0001), particularly in infants (17% vs. 3%, p<0.0001). Among non-b encapsulated H. influenzae, types f (72%) and e (21%) were responsible for almost all cases; the overall case-fatality rate was 9%. Thus, the incidence of invasive non-type b H. influenzae is now higher than that of Hib and is associated with higher case fatality.