Loose Ends in the Epidemiology of the 1918 Pandemic: Explaining the Extreme Mortality Risk in Young Adults

[tetano]

Am J Epidemiol. 2018 Sep 6. doi: 10.1093/aje/kwy148. [Epub ahead of print]
Loose Ends in the Epidemiology of the 1918 Pandemic: Explaining the Extreme Mortality Risk in Young Adults.

van Wijhe M¹, Ingholt MM¹, Andreasen V¹, Simonsen L¹.
Author information

Abstract

In the century since the 1918 influenza pandemic, insights have been sought to explain the pandemic's signature pattern of high death rates in young adults and low death rates in the elderly and infants. Our understanding of the origin and evolution of the pandemic has shifted considerably. We review evidence of the characteristic age-related pattern of death during the 1918 pandemic relative to the "original antigenic sin" hypothesis. We analyze age-stratified mortality data from Copenhagen around 1918 to identify break points associated with unusual death risk. Whereas infants had no meaningful risk elevation, death risk gradually increased, peaking for young adults 20-34 years of age before dropping sharply for adults ages 35-44 years, suggesting break points for birth cohorts around 1908 and 1878. Taken together with data from previous studies, there is strong evidence that those born before 1878 or after 1908 were not at increased risk of dying of 1918 pandemic influenza. Although the peak death risk coincided with the 1889-1892 pandemic, the 1908 and 1878 break points do not correspond with known pandemics. An increasing number of interdisciplinary studies covering fields such as virology, phylogenetics, death, and serology offer exciting insights into patterns and reasons for the unusual extreme 1918 pandemic mortality risk in young adults.


PMID: 30192906 DOI: 10.1093/aje/kwy148

[gsgs]

Copenhagen
break points for birth cohorts around 1908 and 1878.
no notable influenza in the years between the pandemic in the 1830s and 1889(32).
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These results suggest diverging antigenic sins between birth
cohorts. Birth cohorts born before 1873 {1878 or 1873 ?}
may have been exposed predominantly to group 1 influenza A
hemagglutinin,whereas those born between 1873 and 1908
may have been exposed to group 2 , and those born after 1908
may have an antigenic sin related to reemerging group 1,
very likely H1.
It is possible that H1 was also circulating around 1873,
which would explain the low risk among the elderly.
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[avian H1 was] likely introduced in humans between 1900 and 1907.

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this seems all highly speculative to me.
they claim for some "breakpoints" from Copenhagen-data (data not shown)
population = 539000) but none in USA ?, population=103300000
or UK,Japan,.