The lingering effects of the 1890 Russian influenza in Canada: The effect of gestational exposure and socioeconomic inequality on risk of adult mortality from the 1918 Spanish influenza.

It is well known that risk of death during the 1918 Spanish Influenza pandemic was unexpectedly high for those aged 20-40. Analyses of death records show that the greatest number of deaths occurred at the age of 28. It is possible that those people who were born in the period surrounding the 1890 Russian Influenza pandemic were at greatest risk of mortality during the 1918 pandemic, 28 years later. Further, the potential effects of socioeconomic inequality on risk of mortality during the 1918 pandemic has not yet been examined. This paper addresses these two questions using data from Registered Death Records that link individuals who died in Ontario during the pandemic to their birth records. Exact date of birth is used as a proxy for exposure to the 1890 influenza, allowing us to assess the risk of death in 1918 based on prenatal and early life exposure to the 1890 flu. We also link individuals to their entries in the Canadian Census of 1901 and 1911, which provides information on individual socioeconomic conditions over time. We use recently digitized records to investigate the effect of biological insults as well as social structure on mortality during a severe influenza pandemic.