It's been spreading since November 2019, initially news of it was muzzled by China and then they didn't know or didn't have tests for it in other countries.

So it's going to popup everywhere. Any town with an international airport or university with international students will be flooded with cases in a month. Absolutely no-one has immunity since it's never existed before and since everyone feels entitled to still go to work or shop while very sick, it will spread like wildfire.

Also remember there are millions upon millions in the USA without any kind of insurance or easy access to healthcare.