Here is a current article on Spanish flu and it’s origins.
“Writing in the January issue of the journal War in History, Humphries acknowledges that his hypothesis awaits confirmation by viral samples from flu victims. Such evidence would tie the disease’s origin to one location.
But some other historians already find his argument convincing.
“This is about as close to a smoking gun as a historian is going to get,” says historian James Higgins, who lectures at Lehigh University in Bethlehem, Pennsylvania, and who has researched the 1918 spread of the pandemic in the United States. “These records answer a lot of questions about the pandemic.””
The problem with this theory is that Britsh soldiers in France were getting sick before those Chinese laborers were sent across Canada. Of course the origin may still have been China but it may have reached Europe by other means.
http://www.npr.org/templates/story/story.php?storyId=5222069