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Epiglottitis in Sweden before and after introduction of vaccination against Haemophilus influenzae type b.

BACKGROUND
Acute epiglottitis is an important manifestation of invasive Haemophilus influenzae type b (Hib) infection. In 1992 and 1993 Hib vaccination was introduced in the general childhood vaccination program in Sweden. The aim of the present investigation was to study the impact of Hib vaccination on the diagnosis of epiglottitis in Sweden in children as well as adults.


METHODS
A retrospective national population-based study on the incidence of epiglottitis in Sweden was performed for the 10-year period 1987 to 1996. The incidence calculations were based on figures from the national register of all patients treated at Swedish hospitals. The incidence (cases/100,000/year) for the prevaccination period 1987 to 1991 was compared with the incidence after Hib vaccination was introduced.


RESULTS
In children a substantial decrease was found after introduction of large scale vaccination against Hib. Below 5 years of age the annual incidence decreased from 20.9 in 1987 to 0.9 in 1996. In adults a tendency toward a decrease in incidence was evident.


CONCLUSIONS
Introduction of Hib vaccination in a general childhood program was followed not only by a >90% reduction in the incidence in the youngest age group but also by a reduction in the incidence in the older age groups and among adults.