Excess mortality patterns during 1918–1921 influenza pandemic in the state of Arizona, USA S. Dahal 1 , M. Jenner 2 , L. Dinh 1 , K. Mizumoto 1,3 , C. Viboud 4 , and G. Chowell 1,4 1 Division of Epidemiology and Biostatistics, School of Public Health, Georgia State University, Atlanta, GA, USA 2 Barrett, The Honors College, Arizona State University, Tempe, AZ, USA 3 Graduate School of Medicine, Hokkaido University, Kita 15 Jo Nishi 7 Chome, Kita-ku, Sapporo- shi, Hokkaido 060-8638, Japan 4 Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Bethesda, MD, USA Abstract Purpose—Our understanding of the temporal dynamics and age-specific mortality patterns of the 1918–1921 influenza pandemic remains scarce due to lack of detailed respiratory mortality datasets in the United States and abroad. Methods—We manually retrieved individual death records from Arizona during 1915–1921 and applied time series models to estimate the age specific mortality burden of the 1918–1921 influenza pandemic. We estimated influenza-related excess mortality rates and mortality rate ratio increase over baseline based on Pneumonia and Influenza (P&I), respiratory, tuberculosis and all- cause death categories. Results—Based on our analysis of 35,151 individual mortality records from Arizona, we identified three successive pandemic waves in spring 1918, fall 1918–winter 1919 and winter 1920. The pandemic associated excess mortality rates per 10,000 population in Arizona was estimated at 83 for P&I, 86 for respiratory causes, 84 for all-causes and 9 for tuberculosis. Age- specific P&I and tuberculosis excess death rates were highest among 25-44-year-olds and individuals ≥65 years, respectively. The 25-44-year-olds and 5-14-year-olds had highest P&I and tuberculosis mortality impact respectively when considering the ratio over background mortality. Conclusions—The 1918–1921 influenza pandemic killed an estimated 0.8% of the Arizona population in three closely spaced consecutive waves. The mortality impact of the fall 1918 wave in Arizona lies in the upper range of previous estimates reported for other US settings and Europe, with a telltale age distribution of deaths concentrated among young adults. We identified a Corresponding author: Sushma Dahal, MPH, School of Public Health, Georgia State University, Atlanta, GA, USA, sushdahal@gmail.com. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. HHS Public Access Author manuscript Ann Epidemiol. Author manuscript; available in PMC 2019 May 01. Published in final edited form as: Ann Epidemiol. 2018 May ; 28(5): 273–280. doi:10.1016/j.annepidem.2017.12.005. Author Manuscript Author Manuscript Author Manuscript Author Manuscript