The “experts” always want to involve the United States in the Spanish Flu propagation story, but I think there is a greater chance that the “Chinese Labour Corps” workers hired by the British to free up men for front-line duty might have played a role. I believe the French did likewise, too - and all late in the war.
Another special from “Asia”-——
The Asian Flu I had in the Fall of 1957 hit me hard possibly because I had already had rheumatic fever in 1954 and was sickly a lot as a kid.
Smithsonian says:
The pandemic of 1957-58 ultimately caused 1.1 million deaths worldwide, and it follows the 1918 crisis as the second-most severe influenza outbreak in U.S. history. Some 20 million Americans were infected, and 116,000 died.