Control of disease attributable to Haemophilus influenzae type b and the national immunization program.

Abstract

H aemophilus influenzae type b was the most important cause of invasive bacterial disease in young children before introduction of a polysaccharide vaccine in 1985.1 After the availability of conjugated polysaccharide vaccines in 1987, disease caused by H influenzae type b declined by >95% (Fig 1).2 In fact, the reduction in H influenzae type b disease has turned out to be even greater than what many persons predicted, attributable in part to the ability of the vaccine to reduce pharyngeal colonization among vaccinees. This unexpected benefit, which was not fully anticipated from prelicensure clinical trials, stands in contrast to the rare unanticipated adverse event (intussusception) that was not detected in prevaccine trials but occurred after widespread use of the rhesus rotavirus tetravalent vaccine,3 demonstrating that beneficial as well as undesirable consequences may result when new vaccines are used widely. In addition to the remarkable reduction in morbidity and mortality, significant economic benefit has resulted from control of H influenzae type b disease. In this issue of Pediatrics , Zhou et al4 offer an elegant economic analysis of the conjugate vaccine demonstrating that the national H influenzae type b vaccination program offers substantial cost savings from both the direct cost and societal perspectives. Although many current pediatric residents may never treat a child with H influenzae meningitis or epiglottitis because of the rarity of these diseases, more experienced pediatricians readily acknowledge the extraordinary benefits from the significant reduction of invasive disease attributable to H influenzae type b. At a time when immunization programs are being challenged from many nonscientific perspectives, the study by Zhou et al offers important documentation of the cost-effectiveness of one vaccination program.4,5 Fig 1. Estimated incidence of invasive Hib disease, 1987–2000. The bacterium H influenzae was first isolated from respiratory tract …