President Trump is the one who made the decision to not allow any Chinese travel to the U.S., which was met with the usual rounds of "no, no, that's excessive, prejudicial, racist, etc..."

But then Trump did it anyway, protecting the nation.
And every other nation in the world followed suit. Which has done a lot to contain the virus' spread to remain about 98% within China alone. And allegedly the virus had its peak of new cases in China from Jan 23rd and Feb 2nd.
If that turns out to be true, I'll breath a deep sigh of relief when that turns out to be the case.

The only cases so far in the U.S. have been quarantined recent travelers returning from China, and the largest number of those flown back to the U.S. after having been quarantined for two weeks prior aboard a Japanese cruise ship, that in tight quarters spawned a number of cases.

And then in the last 3 days, a sudden explosion of new cases in South Korea (the largest outbreak outside China, 1,000 infected, 10 dead), in Italy (about 200 infections, and a few deaths), and Iran (like China, very unforthcoming, an estimated 95 infections and maybe 16 or more deaths). With no explanation of a clear path how the disease spread to any of these 3 nations.
If the Coronavirus outbreak is mostly in one nation, or just a few, we can prevent its spread by restricting travel to the U.S. from those nations. If it spreads to 20 or 50 or 100 nations, it gets much harder to restrict travel from that many nations.

Tucker Carlson had a rather alarming program last night (Monday, 2-24-2020), even though he was just calmly trying to present the facts of what is possible, that we should prepare for the worst, just in case. By Carlson's account, the news media across the rest of the world is very focused on Coronavirus and warning people what to do. Whereas the U.S. media is oddly silent on the subject, and fixated on another reprisal of "Russia is trying to steal the 2020 election for Trump!!" Yet another overture of the lying Trump is a Russian asset narrative.

It's chilling to think of what would be happening to this country right now if Hillary Clinton or some other establishment Republican were president the last 3 years. There would not have been a ban on Chinese travel, and there would be a lot more cases of Coronavirus in the U.S., perhaps an uncontrollable number.
And without Trump's example, other nations of the world would not have followed that example, and the Coronavirus would not be almost exclusive to China.

Likewise, Trump started a trade war with China about a year ago, and as a result, many companies formerly doing all manufacturing in China had in advance moved much of their manufacturing outside of China to nations like Vietnam, India, the Phillipines, and Indonesia. Thank God!
Under Hillary Clinton or some establishment Republican, we would still be almost 100% dependent on China as our supplier. Thanks to Trump, that dependency was vastly diminished right before this virus hit.

Also to consider, we get our surgical masks and latex gloves, our over-the-counter and prescription drugs from China. 80% of both our parmaceuticals and the ingredients they are made from are in China. Melissa Francis, Dr. Marc Seigel, and others have described this as a potential national security threat to the U.S..
What if China exhausts those supplies fighting their own outbreak, then has none to send us, and we have an outbreak without those supplies?
Likewise, the potential break in supply of electronics we now depend on from China.

As seen on Monday when the stock market crashed, closing down 1,031 points for the day, this has become not only a health crisis, but also an economic crisis.
Over the last month, it has already crippled China's economy.

Now, with the spread to South Korea, Italy and Iran, it becomes far more questionable whether the virus outbreak can be contained. From Italy with open borders to the E.U., it could easily spread to the rest of Europe. THAT is what made the stock market crash, that it will endanger trade and exports from Europe in addition to China.

And Iran, that has a terrible healthcare system and a dishonest government, is one that is most likely not to contain its outbreak and let it spread to other nations.
The more nations it spreads to, the more likely it will reach the United States. And U.S. hospitals are preparing for that risk. What some, including Anthony Fauci of the National Institute of Health, are seeing as an inevitability at some point. A vaccine for Coronavirus is forseen as about a year to 2 years away.