Cross protection between the first and second waves of the 1918 influenza pandemic among soldiers of the Canadian Expeditionary Force (CEF) in Ontario.

Objectives: This research analyses morbidity and mortality during the 1918 influenza pandemic among Ontario soldiers in the Canadian Expeditionary Force (CEF). This paper asks: did exposure to influenza during the first wave confer protection against illness and death during the second wave of the pandemic?

Methods: Pneumonia and influenza (P&I) cases and deaths among Ontario soldiers were transcribed from the 1918 Admission and Discharge books for the CEF. Following the methods of Barry et al.

The first wave of the 1918 influenza pandemic among soldiers of the Canadian expeditionary force.

Objectives: This article evaluates the evidence for the presence of the first, mild wave of the 1918 influenza pandemic among soldiers in the Canadian Expeditionary Force (CEF).

Methods: Death records for soldiers in the CEF who died in Canada in 1917 and 1918 were extracted from the Commonwealth War Graves Commission and record-linked to the Canada War Graves Registers, Circumstances of Casualty database. Monthly mortality rates from pneumonia and influenza (P&I) were compared with mortality rates from all other causes for 1917 and 1918, and by region for 1918.