If we're going to be fair, the thread title really should be "US flu vs China virus". The Spanish Flu may have to be renamed back to the China Flu according to an article in the National Geographic.
HistorianMark Humphriesof Canada'sMemorial Universityof Newfoundland says that newly unearthed records confirm that one of the side stories of the war—the mobilization of 96,000 Chinese labourers to work behind the British and French lines on World War I's Western Front—may have been the source of the pandemic.