[Effect of conjugated PRP vaccines on the incidence of invasive diseases caused by Haemophilus influenzae Type B in childhood].

Prior to the introduction of conjugate vaccines, Haemophilus influenzae type b (Hib) was the leading cause of severe invasive infections in young children, in Switzerland as in other countries. From 1976 to 1990, 150 children were treated for Hib meningitis at the Children's Hospital of Lucerne, corresponding to an annual incidence of 9.2 cases per 100,000 children aged under 15 years. In the same time period, the case fatality rate for meningitis was 4%. 87.3% of the meningitis cases occurred among children aged under 5 years. For this age group an annual incidence of 26.4 cases per 100,000 children was calculated. From 1979 to 1990, 141 children were hospitalized for epiglottitis, corresponding to an annual incidence of 10.9 cases per 100,000 children aged under 15. The introduction of conjugated vaccines resulted in a significant reduction in the frequency of invasive Hib disease. From 1991 to 1992, 9 cases each of meningitis and epiglottitis were observed. In 1993, only one case of meningitis and 2 cases of epiglottitis were seen. For children under 15 years these 21 cases represent annual incidences of 3.2 cases of meningitis and 3.6 cases of epiglottitis per 100,000 children. 2 of 10 meningitis cases occurred in twice vaccinated children under 2 years of age with no signs of immunodeficiency, and another case was seen in a 5-month-old infant vaccinated with only one dose. Assuming a vaccination coverage of 70% among children under 5 during the years 1991 and 1992, the calculated efficacy is 80 to 85% for the vaccine PRP-D in this predominantly affected age group during the period when only this vaccine was available.(ABSTRACT TRUNCATED AT 250 WORDS)