It's the potential for exponential growth that has people concerned: look at growth rate of new cases in Korea, Italy, and Iran in last two weeks. US is harder

It's the potential for exponential growth that has people concerned: look at growth rate of new cases in Korea, Italy, and Iran in last two weeks. US is harder to judge due to lack of testing, may be experiencing the same case rate growth. Numbers in China were bad and it the equivalent of martial law for weeks to slow new cases to a trickle. It's not clear they are out of the woods and may see additional flare ups as they relax restrictions. It's precisely because precautionary measure are being taken (I have seen notices of cancellation and lists of mandatory precautionary measures for more than a dozen events just in last two days).