Impact of non-routine vaccination on the incidence of invasive Haemophilusinfluenzae type b (Hib) disease: Experience in the Autonomous Region of Valencia, Spain

Objective: This study assessed the impact of non-routine vaccination agains t invasive Haemophilus influenzae (Hib) disease before the introduction of universal childhood Hib vaccination. Methods: Data were obtained from a prospective surveillance program for inv asive bacterial diseases in children < 15 years of age that was begun in th e Autonomous Re.-ion of Valencia on 1 December 1995. Results: An incidence of 15.5 cases of invasive Hib disease per 100 000 chi ldren < 5 years of age was reported in the first year of the surveillance p rogram (from I December 1995 to 30 November 1996), when Hib vaccination cov erage was estimated to be 32.5%. An increase in vaccination coverage to 44% in the second year (I December 1996 to 30 November 1997) was associated wi th a reduction in disease incidence to 3.3 cases per 100 000. After the ini tiation of universal vaccination in December 1998, only two cases were repo rted. The effectiveness of non-routine vaccination was 71% in 1997. Conclusions: These results show that before the introduction of routine chi ldhood Hib vaccination, widespread use of the vaccine can dramatically redu ce the occurrence of invasive Hib disease. (C) 2001 The British Infection S ociety.