Changing patterns of invasive Haemophilus influenzae disease in England and Wales after introduction of the Hib vaccination programme

Since 1990 we have been monitoring strains of Haemophilus influenzae referred to the Public Health Laboratory Service Haemophilus Reference Laboratories from all cases of invasive H influenzae disease from five English regions and Wales. Methods of reporting and participating laboratories have remained constant over this period, which allowed us to compare the incidence of infection before and after the introduction of vaccination against H influenzae type b in October 1992. The case definition was a systemic infection in which culture of normally sterile body fluid revealed H influenzae, or the organism was detected by antigen to H influenzae type b. Organisms were identified and typed at the reference laboratories using both type specific antisera …