Considering the 1918 Spanish Flu pandemic occurred in a less populated world not connected by robust air travel networks and still managed to spread to every country in roughly the same timeframe would indicate that neither total population nor air travel are variables in the spread.

If there only was this vast field of computer scientists, mathematicians, physicists, biologists and disease experts that do nothing else but model the spread of infectious diseases.

Not surprisingly it turns out that travel networks play a major role in the early phases of a pandemic [1].

[1] https://science.sciencemag.org/content/342/6164/1337

The day the US stops air travel, many (myself included) will understand the severity of a proposed pandemic.

Since domestic air travel continued unabated and without direct testing to board a flight, it’s not hard to see how many people got the idea that this pandemic wasn’t all that serious.

Dr Fauci never once suggested it - to the best of my knowledge.

It was public health orthodoxy that travel restrictions are some combination of ineffective and counter productive.

Which there are infection scenarios where that might be true. This obviously wasn't one of them.

A standard line is that we couldn't restrict travel in the US because we aren't an island. But we didn't do much of anything, our travel was much more extensive than necessary.

It is also the very first time we are doing it.

Maybe not THAT bad.

For the sake of argument just imagine it was a bio-warfare attack on the US (it isn't) and compare casualties to, say, Pearl Harbor, or 9/11. Before the pandemic, would you have expected US society to sacrifice half a million American lives?