This is absolutely horrific. And the video included underlines the callous disregard these individuals had for human life.
The Canadians blame it on the Chinese, and the British.
https://www.history.com/news/china-epicenter-of-1918-flu-pandemic-historian-says
Note that the standard military treatment for the Flu was 300 mg of Asprin to lower the fever. They patients bled to death in their lungs.