The 1918 influenza pandemic hastened the decline of tuberculosis in the United States: an age, period, cohort analysis

Abstract

The effect of the 1918 influenza pandemic on other diseases is a neglected topic in historical epidemiology. This paper takes up the hypothesis that the influenza pandemic affected the long-term decline of tuberculosis through selective mortality, such that many people with tuberculosis were killed in 1918, depressing subsequent tuberculosis mortality and transmission. Regularly collected vital statistics data on mortality of influenza and tuberculosis in the US are presented and analyzed demographically. The available population-level data fail to contradict the selection hypothesis. More work is needed to understand fully the role of multiple morbidities in the 1918 influenza pandemic.

Keywords: 1918 pandemic; Lexis surface; age; cohort; demography; influenza; mortality; period; selection; tuberculosis.

Figure 1

Tuberculosis (“TB”) and influenza and pneumonia (“FLU”) death rates, for calendar years 1917 and 1918. Death rates per 100,000.

Figure 2

Tuberculosis age-mortality profiles, 1918 (top curve, solid) and 1919 (nested curve, dashed) illustrating drops in tuberculosis mortality. Death rates per 100,000.

Figure 3

Lexis surfaces (age × period false-color diagrams) of tuberculosis death rates, age 1 to 85+, years 1900–53. Left: males; right: females. Legend at right (death rates per 100,000).