date: 2020-04-20 16:10:45 PDT

METHOD

Data are retrieved from the NYTimes Github Repo. This plot is similar to the online chart published by the NYTimes with the addtion that points are encoded for daily estimated case doubling time (the inverse of the growth rate).

Growth is assumed to be exponential. \(t_{double}(t)\) is estimated by:

\[t_{double}(t) = \frac{\int_{0}^{t}cases(t')\; dt'}{cases(t)} \times \log(2)\]

where \(cases(t)\) is the daily reported cases of COVID-19 for a specific location.

Data are reticulated with a spline to reduce noise and derivatives are computed from this smoothed data.

The latest date recorded in the data is 2020-04-19.

HEAT MAP

The maps shows, for counties with > 10 cases, the location, number of current cases, and the calculated growth rate (expressed as doubling time). Shorter doubling times are obviously worse thaan longer doubling times.

As case growth goes to zero, doubling times will tend to infinity. Plots are currently capped at 25 days. Early in the crisis doubling times were on the order of ~ 3 days.

This results saved as heat_map2020_04_20_16_11_30.jpg

SEVERITY WATCH LIST

We can use this data to compute expected new cases in the short term. THis is a ranking of “severity.”

As an approximation, the severity \(S\) is

\[{cases(t)} = {cases(t_0)} \times \ 2^{(t-t_0)/t_d}\]

where \(t_0\) is today and \(t\) is some date in the future. So the severity \(S\) is the extrapoloated number of new cases over the next \(t - t_0 = 14 \; days\). Fourteen days is about the maximum time it takes for CoronaVirus to incubate.

county state current cases double_time forecast new cases
New York City New York 137949.3 14.95 126060.775
Cook Illinois 21781.5 11.21 29983.904
Marion Ohio 1153.4 3.00 28141.134
Nassau New York 30850.2 16.49 24718.760
Suffolk New York 27337.6 16.12 22573.924
Providence Rhode Island 3379.9 5.38 17143.688
Westchester New York 24009.9 18.18 16935.642
Middlesex Massachusetts 8992.1 9.28 16593.830
Union New Jersey 9605.4 11.21 13222.569
Suffolk Massachusetts 8265.6 10.21 13116.390
Philadelphia Pennsylvania 9585.4 11.69 12399.536
Hudson New Jersey 10699.5 12.87 12042.269
Essex New Jersey 10568.7 13.16 11524.888
Los Angeles California 12470.3 15.05 11292.894
Essex Massachusetts 5303.8 8.94 10399.783
Passaic New Jersey 8459.6 12.28 10184.595
New Haven Connecticut 5197.5 8.96 10154.108
Pickaway Ohio 411.7 3.00 10044.828
Bergen New Jersey 12776.3 16.84 9957.266
Minnehaha South Dakota 1573.7 4.90 9828.999

The table generally follows the ranking of the number of cases, but there are some surprises.