A couple of things to think about:

How much of the low incidence count of the disease in the US was due to cutting off air travel to the US from visitors to China 5 weeks ago? Surely that had an impact?

Sadly, the CDC was late in rolling out a test due to it not meeting standards for false-positives and false-negatives. Bit iut makes me wonder how tests in other countries compare? Are some countries that rushed out tests under-counting or over-counting?