to respond to item #1 -
Trump banned Chinese nationals Jan 31. This embargo worked. The proof is, until the Princess airlift, the cases in the US were limited to those airlifted from Wuhan or those in before the ban.
Take for instance, the first Santa Clara, Calif case - declared around Jan 31. This case was only the 7th case in the US on that date. By 2/2, California had four cases. All related to Wuhan. Oregon’s second case was a returnee from So. Korea.
So everything was pretty calm and collected at this point - no big outbreak of direct from china origin, and everybody focused on the Diamond Princess.
Feb 28 - State Dept issues Level 3 travel advisory for Italy and So Korea - both upgraded to Level 4. The CDC instructs travelers to call their health care provider before they visit a facility and follow instructions.
https://www.businessinsider.com/cdc-issues-travel-warning-italy-covid-19-concerns-2020-2
Mar 1 - US announces tighter restrictions on travelers from Iran, South Korea and Italy and assigns Italy a level 4 - do not travel advisory
Mar 1 - California saw another case on 3/1, this one from Egypt. The same day NY saw a case from Iran.
March 2 saw the first cases from Milan, - Georgia and New Hampshire report cases. These had to have been prior to the Level 4 advisory, given 5-7 days incubation..
Mar 2 - airlines suspend travel to Milan (Delta to cut Rome 3/11 or sooner) and travelers are put on a heightened screening and voluntary or mandatory quarantine depending on status
March 3, Berkeley, CA saw a Milan case.
now all these Milan/Italy cases had to have come in before the travel ban, given a 5-7 day incubation, likely a day or two more before reaching out for medical help.
So we have done a decent job on locking down air ports of entry. But the weak spot was and remains commercial sea ports.
The problem is that virus spread is probably several weeks ahead of the reporting in all countries.
So, by the time a country is determined to have a problem, there will already have been lots of flights from there.
Take a look at the current numbers from countries like France, Germany, Spain etc. here:
https://www.worldometers.info/coronavirus/
Look at how fast there are increasing in just one day!
Flights from those countries should have been banned a week ago—we are always a day late and a dollar short.
The ban just slowed the outcome. Coronavirus been up in Seattle since January. Think we got S-CoV in Washington State from China, but L-Cov is coming into Florida and New York from Italy.