"Prior to infantile Hib vaccination, the most commonly observed serotype was serotype b (64,9%). Subsequently, 70,3%, 13,6% and 9,4% of the isolates were untypable, serotype f and serotype b, respectively. Infantile vaccination against Hib resulted in a decrease in the incidence of Hib in all age groups (IRR 0,432 pooled) and a marked increase in untypable H. influenzae and serotype f in children less than 5 years of age (IRRs 2,4 and 3,0, respectively). Hib vaccination has changed the epidemiology of invasive H. influenzae infections in Ontario. Prevention of invasive Hib disease is has been observed in both vaccinated and unvaccinated age groups. Invasive H. influenzae infection now commonly presents as sepsis due to untypable H. influenzae in elderly subjects ... "