"...and they told two friends, and they told two friends, and so on, and so on..."

Here's an interesting and detailed story from The Philadelphia Inquirer on how community spread works:

"A spokesperson for CHOP said the doctor wasn’t required to self-quarantine after his trip abroad because the Centers for Disease Control and Prevention had not designated the country he visited as “Level 3,” or high alert, for the virus. The McCrearys would later find a Facebook photo of the cardiologist in Egypt. CHOP has refused to confirm the physician’s identity; a letter left by The Inquirer at his home was not answered.

Now, with thousands infected or dead, and many more afraid to leave their homes, the disease is imprinted in every corner of our minds. But when the McCrearys took their infant to CHOP, there were no confirmed cases of COVID-19 in Pennsylvania.

They had no idea they could become infected, much less spend five days in intensive care — or that they would unwittingly spread the virus to at least 20 of their friends and family members across communities and counties."

The reporter who wrote this did a great job of digging into the details and sticking to the facts. This is model journalism.
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