Impact of non-routine vaccination on the incidence of invasive Haemophilus influenzae type b (Hib) disease: experience in the autonomous region of Valencia, Spain

Abstract

Objective: This study assessed the impact of non-routine vaccination against invasive Haemophilus influenzae (Hib)disease before the introduction of universal childhood Hib vaccination.

Methods: Data were obtained from a prospective surveillance program for invasive bacterial diseases in children <15 years of age that was begun in the Autonomous Region of Valencia on 1 December 1995.

Results: An incidence of 15.5 cases of invasive Hib disease per 100,000 children <5 years of age was reported in the first year of the surveillance program (from 1 December 1995 to 30 November 1996), when Hib vaccination coverage was estimated to be 32.5%. An increase in vaccination coverage to 44% in the second year (1 December 1996 to 30 November 1997) was associated with a reduction in disease incidence to 3.3 cases per 100,000. After the initiation of universal vaccination in December 1998, only two cases were reported. The effectiveness of non-routine vaccination was 71% in 1997.

Conclusions: These results show that before the introduction of routine childhood Hib vaccination, widespread use of the vaccine can dramatically reduce the occurrence of invasive Hib disease.