I think the timeline of when different countries started seeing it pop up (after China) has been driven by how commonly those places are travelled to by people from outside of them. Global urban centers. Africa, for example, (I think) still has very few cases.

Even within the U.S., the map very clearly highlights frequently-travelled urban centers (California and New York first, followed by Washington/Oregon, then Texas, Florida, etc.). It looks like the map of the Democrat/Republican leaning for different states.