[evil-olive]

As of Monday there were 18 confirmed cases in WA [0]. So even the lower bound of that confidence interval supports the claim that the number of actual cases is significantly higher than the number of confirmed cases (though "only" 4-5 times higher, rather than 10-30 times).

0: https://www.washingtonpost.com/world/2020/03/02/coronavirus-...

[pmiller2]

What should anyone do differently if there are 18 cases vs 80?

[troydavis]

If you're going to pick a number to plan for, it's 570, not 80. Yes, the range of possible values includes 80, but it also includes 1500.

So, what would 570 (out of King + Snohomish County population of 3 million) mean? 22% of the population is under 18, so something like 125 minors would have had it (King County has ~600 schools).

The doubling period is 7 days, so ~275 of those cases would have been in week prior to March 2 and ~570 new cases could be expected between March 3-10. If 20% of those need hospitalization[1], that would be ~100 new beds.

With 570 patients (and 275 new), contact tracing is both impossible and ineffective. Let's optimistically assume that people notice their fever immediately and self-quarantine flawlessly. Even then, we don't know who these people encountered in the few days before symptoms began and can't notify them specifically. Either we accept whatever retransmission rate occurs during that period, or do what we can to reduce it by reducing the population-wide minutes spent within 6' of other people.

[1]: https://www.washingtonpost.com/world/europe/coronavirus-in-i... and others