We also have jets and international air travel that can take a patient zero anywhere in the world and around any people in a matter of hours (well before they'r

We also have jets and international air travel that can take a patient zero anywhere in the world and around any people in a matter of hours (well before they're too sick to know not to be traveling). With the Spanish flu in 1918 it took months for it to get around, mostly through rail and steam ships. With COVID-19 we saw some variants explode around the entire globe in a matter of _weeks_.