Decreases in invasive Haemophilus influenzae diseases in US Army children, 1984 through 1991

Abstract

<h3>Objective.</h3> —To document trends in the incidence of invasive<i>Haemophilus influenzae</i>diseases in young children of US Army active duty soldiers following the publication of<i>H influenzae</i>type b immunization recommendations for young children between 1985 and 1990. <h3>Design.</h3> —A population-based surveillance of hospital discharge diagnoses for<i>H influenzae</i>invasive diseases. <h3>Setting.</h3> —Military and civilian medical treatment facilities around the world. <h3>Patients.</h3> —There was a mean population of nearly 200 000 US Army health care beneficiaries younger than 5 years of age each year of the study. <h3>Outcome Measures.</h3> —Annual total and age-specific incidences of the six most common<i>H influenzae</i>invasive diseases in this population (meningitis, epiglottitis, septicemia, pneumonia, cellulitis, and septic arthritis). <h3>Results.</h3> —The annual number of cases of<i>H influenzae</i>invasive diseases decreased from a high of 188 in 1986 to 43 in 1991. The incidence in the age group at highest risk for<i>H influenzae</i>disease, those 6 to 11 months of age, decreased from 355 per 100 000 children in 1986 to 116 per 100 000 in 1991 (<i>P</i>&lt;.0001 χ²for trend). The incidence for<i>H influenzae</i>meningitis declined from 59 per 100 000 children in 1986 to 6 per 100 000 in 1991 (<i>P</i>&lt;.0001, χ²for trend). <h3>Conclusions.</h3> —The decrease in<i>H influenzae</i>invasive diseases closely follows the dates of<i>H influenzae</i>type b vaccine licensure for use in progressively younger age groups. Some age groups, however, experienced a decline in disease rates even before becoming eligible for vaccination. (<i>JAMA</i>. 1993;269:227-231)