I will probably be downvoted for saying this, but... The seasonal flu alone kills half a million people every year. So any mild disease that is as contagious and barely twice as fatal will kill 1 million. And that's what's going to happen with COVID19. It is far more severe than the flu. We know COVID19 is as contagious, given how fast it's spreading and how unstoppable it is (R0>2, asymptomatic transmission, airborn…
It very clearly is and it's out of the box, they can't stop it now. The US should be shutting down all travel into and out of the country, full quarantine from the rest of the world. We'd have a chance at stopping it from doing to the US what it has done to China, if we acted immediately, before it's across Europe and more of Asia and then imported in stealth mode by travelers from those regions that are unaware they're infected.
Back in reality, the US economy will look like China's frozen economy, within a month or two, unless Covid is stopped soon. More likely, it's going to spread from Italy across Europe, and continue to spread across Asia. From those hyper economic zones, the US will be guaranteed to import it from multiple sources (no single country to shut down travel with).
China went full totalitarian to an extreme, and couldn't stop it. Covid froze the second largest economy and did it in the span of a month. What chance does the rest of the world stand at stopping it? None.
Bill Gates is worried about it spreading across Africa (and said in an interview a few weeks ago, when asked about his plans for the year: "well, I plan to travel a lot less this year" - yeah). He's obviously properly worried. It will kill a large number of people in poorer economic regions that will see their healthcare resources overwhelmed. The US is nowhere near prepared for what's likely about to hit.