Racial Disparities in Mortality During the 1918 Influenza Pandemic in United States Cities

Area of Science:

• Epidemiology
• Public Health
• History of Medicine

Background:

• Extreme racial health inequality existed prior to the 1918 influenza pandemic.
• Significant disparities in influenza and pneumonia mortality between non-White and White populations were documented.
• The 1918 pandemic saw a notable, uniform reduction in these racial mortality gaps across US cities.

Purpose of the Study:

• To provide a comprehensive account of reduced racial mortality disparities during the 1918 influenza pandemic.
• To examine potential explanations for the uniform reduction in these disparities across cities.
• To offer a framework for understanding infectious disease mortality disparities.

Main Methods:

• Linking multiple data sources for a complete account of racial disparities.
• Examining city-level sociodemographic factors, including segregation and nonpharmaceutical interventions.
• Investigating racial differences in exposure to the 1918 "herald wave" and early-life influenza exposures.

Main Results:

• Reduced racial disparities in influenza and pneumonia mortality were unexpectedly uniform across cities.
• Little evidence supported sociodemographic factors, nonpharmaceutical interventions, or herald wave exposure as primary drivers.
• Suggestive evidence indicated that childhood exposure to the 1889-1892 influenza pandemic may have reduced 1918 disparities.

Conclusions:

• Prior influenza exposure, particularly in childhood, may have shaped immunological vulnerability and reduced racial disparities in 1918.
• Differential behavioral responses to the herald wave might have protected non-White urban populations.
• Understanding infectious disease mortality requires considering microbial agents and the social histories of affected populations.