Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Comparative Study
. 1997 Dec;87(12):1944-50.
doi: 10.2105/ajph.87.12.1944.

The impact of influenza epidemics on mortality: introducing a severity index

L Simonsen  1 , M J Clarke, G D Williamson, D F Stroup, N H Arden, L B Schonberger
Affiliations
Comparative Study

The impact of influenza epidemics on mortality: introducing a severity index

L Simonsen et al. Am J Public Health. 1997 Dec.

Abstract

Objectives: The purpose of this study was to assess the impact of recent influenza epidemics on mortality in the United States and to develop an index for comparing the severity of individual epidemics.

Methods: A cyclical regression model was applied to weekly national vital statistics from 1972 through 1992 to estimate excesses in pneumonia and influenza mortality and all-cause mortality for each influenza season. Each season was categorized on the basis of increments of 2000 pneumonia and influenza excess deaths, and each of these severity categories was correlated with a range of all-cause excess mortality.

Results: Each of the 20 influenza seasons studied was associated with an average of 5600 pneumonia and influenza excess deaths (range, 0-11,800) and 21,300 all-cause excess deaths (range, 0-47,200). Most influenza A(H3N2) seasons fell into severity categories 4 to 6 (23,000-45,000 all-cause excess deaths), whereas most A(H1N1) and B seasons were ranked in categories 1 to 3 (0-23,000 such deaths).

Conclusions: From 1972 through 1992, influenza epidemics accounted for a total of 426,000 deaths in the United States, many times more than those associated with recent pandemics. The influenza epidemic severity index was useful for categorizing severity and provided improved seasonal estimates of the total number of influenza-related deaths.

PubMed Disclaimer

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Am J Epidemiol. 1981 Mar;113(3):215-26 - PubMed
    1. Epidemiology. 1997 Jul;8(4):390-5 - PubMed
    1. Stat Med. 1988 Oct;7(10):1045-59 - PubMed
    1. JAMA. 1961 Jun 3;176:776-82 - PubMed
    1. J Infect Dis. 1982 Sep;146(3):313-21 - PubMed

Publication types