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

Abstract
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 and a polymerase chain reaction method.1 Brief clinical details were also collected. The results for the first two years of the survey showed that most H influenzae infections were due to type b, presented as meningitis, and occurred in children under 5,2 suggesting that mass vaccination of infants should achieve a rapid change in the pattern of invasive H influenzae infections.