How Infected is New York City Metropolitan Area?

New York City (NYC) metro area has been one of the hardest-hit areas in the world during the COVID-19 pandemic.  Whether defined as the Metropolitan Statistical Area (MSA) with 20.3 million, or the broader Combined Statistical Area (CSA) with 23.7 million it has the largest population in the United States and the activities of residents are closely intertwined.  All 31 counties in the CSA have been heavily infected by the coronavirus.  By itself, this CSA would be the most heavily infected country in the world with the heaviest death toll. 

County	Infections	Infections	Deaths	Mortality	Mortality
	% pop	Count	Count	Rate	% pop
Bronx	2.28%	32,711	3,287	10.0%	0.23%
Brooklyn	1.51%	38,964	4,730	12.1%	0.18%
Manhattan	1.13%	18,383	2,039	11.1%	0.13%
Queens	1.98%	45,024	4,544	10.1%	0.20%
Staten Island	2.25%	10,722	769	7.2%	0.16%
Westchester	2.61%	25,276	838	3.3%	0.09%
Rockland	3.00%	9,699	401	4.1%	0.12%
Nassau	2.33%	31,555	1,431	4.5%	0.11%
Suffolk	1.98%	29,476	926	3.1%	0.06%
Orange	1.86%	7,151	243	3.4%	0.06%
Bergen	1.47%	13,686	876	6.4%	0.09%
Hudson	1.79%	12,039	568	4.7%	0.08%
Essex	1.43%	11,387	888	7.8%	0.11%
Union	1.88%	10,484	481	4.6%	0.09%
Passaic	1.80%	9,392	327	3.5%	0.06%
Middlesex	1.10%	9,047	369	4.1%	0.04%
Fairfield	1.05%	9,883	584	5.9%	0.06%
TOTAL	1.79%	324,879	23,301	7.2%	0.13%

We look at 17 of these counties with the closest commuting distance to Penn Station in Manhattan, summarized in the table above.  These counties have a total population of 18.1 million and comprise 77% of the CSA.  Every day, millions of commuters enter NYC (including The Bronx, Brooklyn, Manhattan, Queens, and Staten Island) for 4.2 million jobs, and then many return to their homes in the NY-NJ-CT-PA area.  Any disease they pick up in NYC quickly and easily spread into the neighboring counties. This has made the entire region the hottest in the world with 1.79% of the population in the17 counties confirmed infected and 0.13% of their population killed by COVID-19.  These numbers are 3 to 4 times worse than for next hardest-hit countries. 

How did metro NYC get this bad?  One reason is the lack of a coordinated regional or national policy and program to deal with the pandemic in the complex multi-state CSA.  The other is the late start to quick, accurate, and comprehensive testing.  Some epidemiological models suggest that on March 1 when the first confirmed COVID-19 case was found in NYC, as many as 10, 000 cases had already spread in the region since late January.  Of course, testing has improved several hundred-fold since March and the number of hidden cases is no longer 10,000 times the number of confirmed cases.  However, several antibody test programs suggest that the hidden population may still be 30 to 50 times larger than the confirmed population in areas like Santa Clara County and Los Angeles County.  Were this true in NYC it would imply that NYC has already achieved herd immunity which it obviously has not as evidenced by the several thousand new cases reported very day.  A more recent antibody detection test conducted in NYC found that 21% of the population may be infected already.  We believe that this, too, is an over-estimate due to very high false positives from the test.  Our estimate, based on current COVID-19 testing efficiency (43% of tests return positive results) and testing completeness (2.9% of the population tested) in the CSA is that testing is uncovering about 85% of all the serious cases and 30% of all the infected cases in the region.  The vast majority of the hidden population comprises asymptomatic or mildly symptomatic cases that currently do not qualify for testing due to limited availability.  This means that 6% (=1.79% * 3.3) of the 17-county metro-NYC area could already be infected and that herd immunity (generally believed to require 60% of the population) could be achieved before August or sooner if regional lockdowns were relaxed or lifted.  The good news is that as of April 22, testing has doubled from last week’s average to over 300,000 per day, although many pockets of shortages remain and it remains to be seen whether this pace is sustainable.  In addition, the mortality rate is probably not as bad the 10.5% measured for NYC (including all probable cases as currently recommended by the CDC), but possibly just 5% when all COVID-19 cases are counted.  This would nevertheless translate to 25,000 deaths in NYC and 45,000 deaths for the NYC CSA by July 1.   

One lesson to be learned is that early, strong, and coordinated action by the regional and national government is required to minimize the pandemic toll.  Early and comprehensive testing and tracking, and treatment is an essential part of that government response.  Another lesson from metro-NYC is that without a lockdown, the testing and health care systems would have been overwhelmed.  As it turned out, peak hospitalizations surpassed capacity for many days in NY, and on some days testing returned near 70% positive results in NJ.  That meant that they were testing near-certain cases (actually the wrong thing to do with limited testing capacity) and missing many serious cases.  The eight states who refused to impose state-wide lockdowns would do well to learn from NYC's and other states' examples.