I’ve been swimming in numbers over the last couple days. I find numbers, create charts, all to try to make sense of the emerging story. One thing that is very clear in all of this is that there is as yet no US outbreak; even the nationwide numbers are misleading. What you have is a New York state and especially New York City outbreak and then a series of much smaller regional ones, most of which are running significantly behind what is happening in New York. One way to capture this: 68% of the hospitalizations in the country are in New York State.
I note the data on hospitalizations because they are key not only in the obvious sense of critical cases but because they are a key, relatively ‘hard’ metrics amidst the informational chaos.
Especially during the acute periods of crisis, which we are really only now entering, numbers of cases tell us relatively little. We know we are undercounting the true number of infections. But we don’t know how much we are undercounting.
One key pattern in the numbers is that New York State’s percentage of positive results per test has been dramatically higher than everywhere else in the country. Yesterday New York had 37% of its tests come back positive. Nationwide the number was 15%, and that’s inclusive of the New York numbers. That pattern has been consistent. New York’s percentage of positive tests has gone up every day but one since March 18th. A big part of that is because New York State is ground zero of the outbreak. We have lots of infected people. But that’s not the only reason.
The other reason seems to be that New York is following a much tighter protocol in doing tests. Put another way, they’re targeting their tests more efficiently. The number of new infections per day has actually leveled off in New York over the last few days. That sounds like good news and it might be the early signal of some stabilization. But if you look closely the state has conducted fewer tests. The number peaked at 16,888 on Monday and fell to 12,981 yesterday. That is in line with policy which is focusing on testing only those with acute cases and particularly in hospitals.
What all of this comes down to is that with relatively low levels of testing the hard numbers of hospitalizations and fatalities are not only the most important in human terms. They are also the most important in terms of knowing where we are. Those are the data points that tell us most clearly where we are in the outbreak since we’re not able to test at scale or it doesn’t make sense to prioritize testing at scale to get the total numbers.
Along these lines here is one more piece of information.
A new pre-print, as yet un-peer-reviewed, released on the 22nd and updated on the 23rd attempted to work back from fatality data to estimate the percentage of symptomatic cases that different countries are confirming. They also apply models to take account of a number of key factors, including the fact that fatalities lag finding new cases. The results may surprise you. The study estimated that the United States is finding 13% (range 11% – 16%) of its symptomatic cases. That’s pretty lower. But most European countries are actually significantly lower. Italy had found 4.7%; France 9.2%, UK 6%. In very different category are Germany 69%, South Korea 83%, Austria 67%, Sweden 46%. I should emphasize: these are not facts. They are estimates based on sophisticated data-modeling by qualified researchers.
Other parts of the country now have a critical few days, maybe a week or in some cases more, to see what is coming through the prism of New York and lockdown as rapidly as possible.