Going Coronaviral: New York City Will Be Shut Down By the End of Next Week

Note: To read an updated and improved version of this post, please click here. It has more accurate numbers and clearer explanations, and I recommend you read it instead.

If that title seemed half funny, this post, unfortunately, will not. Panicking never helps, so please don’t panic, but by the end of next week, New York City will likely be shut down. Here’s why, in four graphs.

COVID-19 Confirmed and Predicted Cases in NYC as of 14th March 2020.png
As I captioned in a previous post: “Note the near perfect match – on the left – of the data for confirmed cases in NYC through yesterday (Friday, March 13th, 2020) with the best-fit exponential growth curve, and the ominous implications of that match – on the right – suggesting that rather than the 1,000 confirmed cases Mayor de Blasio warned us to expect by next week, we could easily see three or four thousand. Yes, more drastic measures have started to be taken, but if we assume – fairly, in my view – that no meaningful action was taken at scale to stem the spread of SARS-CoV-2 (the novel coronavirus) in NYC until yesterday, and given that the incubation period of the virus is ~5-6 days, then we shouldn’t expect to see any noticeable drop in new confirmed cases owing to our, and the City’s efforts, until around this time next week. Hang on. Stay safe and stay sane. And, please, be good to yourself and each other. We’ll come through this together.” (This graph was created by Tom O’Keefe. Feel free to use it however you like, but please do give credit. Thanks.)

Sadly, it gets worse. Accordingly to the following graph from a study by the Journal of the American Medical Association (JAMA) of ~45,000 cases of COVID-19 in Wuhan, the number of confirmed cases (here: “By date of diagnosis”) lags but roughly mirrors the number of actual cases (here: “By date of onset”) by roughly a week.

Screen Shot 2020-03-14 at 6.56.15 PM.png
This is from JAMA.

Put simply, the trends or the curves look more or less the same (if anything, the number of actual cases climbs more steeply until the drastic preventive measures – in this case, the “shut down” of Wuhan, a city with a population greater than that of the five boroughs – take effect), so we can approximate the number of actual cases by simply extrapolating the predicted number of confirmed cases a week ahead. There’s no saying that the pattern in New York is exactly analogous to that in Wuhan, but, in both cases, municipal, provincial/state, and national governments were caught totally unprepared by a novel pathogen, and – in spite of having had two-plus months lead time and the advantage of their example – I wouldn’t say we’ve done any better in handling this here than our peers in Wuhan did there.

That said, let’s apply this same approach to the New York numbers. This gets very ugly. (See correction below! Owing to a math error I made, this turns out to be at once an underestimation of the worst-case scenario, and an overestimation of the likely outcome. The corrected estimates are still terrifying.)

Screen Shot 2020-03-14 at 7.05.37 PM.png
(Correction: This graph was based on a faulty assumption. Better estimates can be found in this updated post.) The green curve shows the predicted number of confirmed cases. The blue line shows the predicted number of actual cases (that is, the total number of cases, confirmed or unconfirmed). Note, for today, the model predicted 212.46 confirmed cases and subsequently announced official number was 213. (This graph was created by Tom O’Keefe. Feel free to use it however you like, but please do give credit. Thanks.)

I’ve made multiple assumptions here (about the trend of confirmed cases going forward and the relationship between confirmed cases and total actual cases, most saliently), but all founded on the best available data of which I’m aware. If these numbers are anywhere near correct, then we could be looking at ~100,000 actual cases of COVID-19 in New York City by next weekend. New York City has ~20,000 total hospital beds and 5,000 ventilators. Given that ~20% of COVID-19 patients require hospitalization, and approximate 5% of patients require intensive care, we could be at or beyond the capacity of the City’s medical system by this time next week. This is why the idea of flattening the curve became ubiquitous in recent days; unfortunately, we’ve likely missed the opportunity to flatten it enough to avoid a real crisis, but what we do in the coming days will determine how bad that crisis gets. Every day we delay, this gets worse.

If it’s helpful, and for people to prove me wrong in case I am, below are the NYC data and predicted values upon which the graphs are based.

Screen Shot 2020-03-14 at 7.33.50 PM.png
Sorry for not rounding. I was in a hurry.

Postscript: Correction. I caught my own error before someone else could. I conflated rate of change in the JAMA graph with the trend itself. Just ran the numbers again (leaving the erroneous spreadsheet – only the “Estimated Cases” are incorrect – above from the original post, and will try to share corrected spreadsheet in the morning). For better estimates and clearer explanations, please read this post instead.

Screen Shot 2020-03-15 at 9.37.50 AM.png
It hardly feels like good news to say that we could only have tens of thousands of cases of COVID-19 in New York City by the end of next week, but, for sake of comparison, this final graph shows four different scenarios, plus the predicted number of  confirmed cases data (here in blue) from our second graph which, as in the fourth graph, now looks very small.
Briefly:
Green plot points show the worst-case scenario from above (~140,000 cases by Friday, March 20th);
Purple plot points show a scenario under which drastic measures are taken starting on Wednesday, the 18th (~97,000 cases by the 20th);
Red plot points show a scenario under which drastic measures are taken starting on Wednesday, the 18th (~54,000 cases by the 20th);
While the yellow show what could have happened had we taken drastic measures (as opposed to half measures) starting on Friday, March 13th (leading to only ~14,000 cases by the 20th).
Note that the red plot points are identical to the green through the 16th, and purple plot points are identical to the green through the 18th, while yellow points diverge from green after the 12th.

 

 

 

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