Wednesday, April 8, 2020

Is New York Containing Covid?

The above shows the new daily positive test count (and a couple of moving averages) in New York state.  That's the lines in the middle ending at around the 9000/day level.  The general impression of this is that the "PAUSE" (stay at home) order that Governor Cuomo ordered as of March 22nd has, after a two week delay, caused a leveling off in new cases, but not a decline - though it's very early to be sure.  We would expect something like a 10-14 delay as there's a five day incubation period from infection to symptoms, and then more delay getting a test and waiting for the result.

The blue line is new daily hospitalizations.  I don't see the decline in this recently as a good thing - given that the positive test load is not declining, this looks more likely an issue of hospital capacity than of new demand for hospitals declining.  There is significant reporting now suggesting that a lot more New Yorkers than usual are dying at home because they either can't or won't go to hospital when very sick.  The yellow line at the top is total number currently in hospital with Covid.  Again, the rate of increase declining seems like a bad thing in the absence of a decline in new cases.

Note that the data here is of extremely poor quality and it's very hard to be sure of any conclusion.  For example, here is the fraction of new daily tests that are positive:

This indicates the testing infrastructure is very maxed out - people are only getting tested if they very likely have the disease, and no doubt lots of milder cases are being missed.  Thus the positive test count in the first graph above is likely a gross underestimate.  Note the tests are thought to have a 30% false negative rate, so the ratio shouldn't go above 70%.  If all was well, and we were vigorously chasing down contacts of cases, less than 5% of tests would come back positive.  The slight decline in recent days might be the beginning of a good thing (or it might be a sign of more epidemic outside the New York City area, where capacity is not so maxed out).

All told, I think we can conclude that the PAUSE has definitely had a substantial effect on slowing the epidemic.  It's very hard to be sure, but the reproduction number might be right around the 1.0 threshold, giving an ongoing epidemic of roughly constant size.  The hospital system is badly maxed out and there are a lot deaths outside of the system.

A few weeks ago, I speculated "New York is in serious and, I would guess, irrecoverable containment failure." That now seems to be hanging in the balance. I also suggested it was about to become "the greatest shitshow on the planet" and that part seems right.

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