Not a student of history but seems like this would be expected
Spanish flu went around the world several times without massive international travel
It was spread by the movement of troops which was extensive.
“Spanish flu went around the world several times without massive international travel”
You do know that there was a war on then, right? Two million Americans and 424,000 Canadians went to Europe, 335,000 Australian and 100,000 New Zealanders were deployed overseas. About a half million Africans fought in Europe. There were civilian laborers too, including about 140,000 brought from China. That’s how the virus spread.