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Article
April 7, 1989

Interannual Variation of the Incidence of Haemophilus influenzae Type b Meningitis

Author Affiliations

From The Children's Hospital and Medical Center, Seattle (Drs Sherry and Smith and Ms Char); The Maternal and Child Health Program (Drs Sherry and Emanuel) and the Departments of Epidemiology (Drs Sherry, Emanuel, and Gale) and Biostatistics (Dr Kronmal), University of Washington, Seattle; and Mary Bridge Hospital, Tacoma, Wash (Dr Walkley). Read in part at the 1987 Annual Meeting of the American Public Health Association, New Orleans, Oct 21, 1987.

From The Children's Hospital and Medical Center, Seattle (Drs Sherry and Smith and Ms Char); The Maternal and Child Health Program (Drs Sherry and Emanuel) and the Departments of Epidemiology (Drs Sherry, Emanuel, and Gale) and Biostatistics (Dr Kronmal), University of Washington, Seattle; and Mary Bridge Hospital, Tacoma, Wash (Dr Walkley). Read in part at the 1987 Annual Meeting of the American Public Health Association, New Orleans, Oct 21, 1987.

JAMA. 1989;261(13):1924-1929. doi:10.1001/jama.1989.03420130092030
Abstract

We conducted a population-based retrospective cohort study to define the annual age-specific incidence of Haemophilus influenzae type b meningitis for birth to 5-year-old residents of King County, Washington, from January 1977 through December 1986. We found naturally occurring wide interannual variations in incidence. The standard deviations of the age-specific incidence during the eight years before the introduction of H influenzae vaccine varied from 26% to 115% of the mean. If short-term changes in incidence were used to assess the efficacy of an H influenzae vaccine (which is <100% efficacious and not administered to all susceptible children), the conclusions could be erroneous. To avoid this bias, long-term cohort studies, case/control studies using concurrent controls, or large clinical trials are better choices. We found no significant change in overall incidence during the ten-year study period.

(JAMA. 1989;261:1924-1929)

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