Open AccessThe 1918 influenza pandemic in N ew Y ork C ity: age‐specific timing, mortality, and transmission dynamics
Author(s) -
Yang Wan,
Petkova Elisaveta,
Shaman Jeffrey
Publication year - 2014
Publication title -
influenza and other respiratory viruses
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.743
H-Index - 57
eISSN - 1750-2659
pISSN - 1750-2640
DOI - 10.1111/irv.12217
Subject(s) - demography , pandemic , transmission (telecommunications) , outbreak , population , medicine , mortality rate , covid-19 , virology , disease , sociology , infectious disease (medical specialty) , electrical engineering , engineering
Background The 1918 influenza pandemic caused disproportionately high mortality among certain age groups. The mechanisms underlying these differences are not fully understood. Objectives To explore the dynamics of the 1918 pandemic and to identify potential age‐specific transmission patterns. Methods We examined 1915–1923 daily mortality data in N ew Y ork C ity ( NYC ) and estimated the outbreak duration and initial effective reproductive number ( R e ) for each 1‐year age cohort. Results Four pandemic waves occurred from F ebruary 1918 to A pril 1920. The fractional mortality increase (i.e. ratio of excess mortality to baseline mortality) was highest among teenagers during the first wave. This peak shifted to 25‐ to 29‐year‐olds in subsequent waves. The distribution of age‐specific mortality during the last three waves was strongly correlated ( r = 0·94 and 0·86). With each wave, the pandemic appeared to spread with a comparable early growth rate but then attenuate with varying rates. For the entire population, R e estimates made assuming 2‐day serial interval were 1·74 (1·27), 1·74 (1·43), 1·66 (1·25), and 1·86 (1·37), respectively, during the first week (first 3 weeks) of each wave. Using age‐specific mortality, the average R e estimates over the first week of each wave were 1·62 (95% CI: 1·55–1·68), 1·68 (1·65–1·72), 1·67 (1·61–1·73), and 1·69 (1·63–1·74), respectively; R e was not significantly different either among age cohorts or between waves. Conclusions The pandemic generally caused higher mortality among young adults and might have spread mainly among school‐aged children during the first wave. We propose mechanisms to explain the timing and transmission dynamics of the four NYC pandemic waves.