mmm no, travel restrictions don't explain the death rates dropping off like they have. Populations were already seeded before travel restrictions were put in place. Once the virus is in the community exponential growth in infections with death rates lagging by a few weeks is all one needs to explain those early growth rates. The claim is that by locking down the population, the community managed to reduce case rates followed by drops in death rates. This part of the theory that we talked about last night.
Simulations showing how lockdowns affect those curves is shown here:
Here's an article about Seattle and how it used social distancing as well as testing to flatten the curve. It's not as if I'm saying anything novel or surprising. Nor was what Hong Kong or Korea did much different. Social distancing, shelter in place, etc are crude tools but effective.
"One thing that stands out in terms of blunting the velocity of the virus is how quickly in the Seattle area . . . they were able to institute social distancing," said Lee Riley, a professor at the University of California at Berkeley and chair of the university's Division of Infectious Diseases and Vaccinology. "That's probably the big factor in all of this. In Hong Kong, Singapore, Taipei, Korea and other places where they saw early success, you saw the same thing."
The message I'm getting from all of this is, social distancing, lockdowns, isolating sick and potentially infected people works. What works best and has the smallest footprint on the community is doing that quickly and in targeted intelligent actions, before very many people are infected and spread it widely. NY and NOLA didn't act soon enough.
A US-wide lockdown is IMO opinion not necessary. Vigilance and where the virus flares up, quick action to enact social distancing measures, is how we will be able to come back out and enjoy ourselves again.