It was spreading in China. The first registered case in the US was on January 20th.Also This virus didn't start spreading in late January. It was spreading before then. Reports started in early December. It was well known about mid January.
Also from that link, which is where I got my info it states this:
CDC estimates that so far this season there have been at least 39 million flu illnesses, 400,000 hospitalizations and 24,000 deaths from flu.
So the flu had a 3 month start and is at 39 million. Do you think the covid 19 will be at 39 million in 3 months?
If there were no measures ABSOLUTELY it would go way past 40M(and even with measures it's very possible it goes past 40M, it just might take longer depending on the measures). The best estimations all around the world - from China to South Korea to Europe to the US is that the number of infected jumps by about 35% every day, or lets say it doubles every 3 days... (again this is if there is no measures - if there is no social distancing, if the schools are working, if everybody is working like normal, etc.). You can do the math, it's really not that hard...
Lets say there are 150K cases in the US right now.
Day 0 - 150K
Day 3 - 300K
Day 6 - 600K
Day 9 - 1.2M = for simplicity sake, lets say it's 1M
Day 12 - 2M
Day 15 - 4M
Day 18 - 8M
Day 21 - 16M
Day 24 - 32M
Day 27 - 64M
Day 30 - 128M
This is one month from now.
On day 33 it would have infected 3/4ths of the US population(about 250M). This is all very simplified because after some point herd immunity takes effect and it will drop down simply because it will run out of oxygen(new people to infect and most people it meets will already be infected) but you get the picture. And again, I want to underline this part - this is if no measures are taken.
Here's a video from 1 month ago that talks about the epidemic on a world scale and exponential growth. It's scarily accurate with its prediction:
It takes into account that most countries are taking steps to combat it and it fits the growth with what has been observed by that period of time(by March 6th). The best fit of the graph is that with the measures taken the disease will continue spreading multiplying the existing cases by 10 every 16 days. They projected it will hit 1M cases in 30 days(by April 5th). We are at 740K right now. Can you guess how many we will have by April 5th? About 1M. Maybe even more. This is exponential growth. Until you break the exponential growth, the curve gets real steep the later you go. By that curve, if we keep the same tempo, on April 22 we will have about 10M cases worldwide and 100M by May 9th and 1 billion by the end of May.
Last edited: