Growth in case counts in S Korea, Italy, Iran reflects testing strategy, in part. They are looking more so they are finding more. This is why expanding diagnostic capacity in the US is so urgent. We aren’t doing enough surveillance to understand when/if/how much community spread.
There is a possibility that we may someday learn we have had community transmission in the US for a while. Case counts may lappear to grow very fast, like in Italy, and it will feel overwhelming.
If that imagined scenario does come to pass, we should keep a steady hand - the numbers are about testing and reporting, not a real-time transmission ticker.
