Spread of a Disease

Bit of a long read, but fascinating mathematics behind the spread of SARS-CoV-2. The upshot being that even as newly reported cases of the virus level off, the number of “true” cases (e.g. the ones that were present but never tested or from folks showing no symptoms at that point) continue to grow exponentially.

Example. Mark gets tested today and is positive for SARS-CoV-2. Mark was actually infected 2 weeks ago, but only got tested today when he started showing symptoms. Mary had lunch with Mark five days ago, and is now infected but not showing any symptoms. Five days from now Mary will feel ill and test positive. On the day Mark tests positive, we “know” about one (1) case but there’s at least two (2) – him and Mary. The “known” cases are one, the “true” cases are two – and most likely even higher.

And as any healthcare worker will tell you right now, it’s not about the severity of the disease but instead the capacity of the health care system to be able to handle that exponential influx of sick people. I’ve seen figures for hospitals in the US already operate at 90% capacity. If you become ill and need a ventilator – there might not be one to give you.

Anecdotally from doctors and nurses on the front lines: choices are being made now, every day, about who lives and who dies because of a lack of equipment.

It’s only going to get worse.

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