Well, this isn't a surprise at all. The rates are dropping, as testing is increased, and we are finally seeing some real numbers, showing that the panic that's been pushed isn't necessary.
As major news outlets like the New York Times have updated
the number of cases of COVID-19 and confirmed deaths from it, a new
trend has emerged: the death rate, measured as the number of deaths
divided by the number of cases, is falling.
Six days ago, on March 12th, there were 36 deaths caused by the virus in the U.S. out of a total of 1,215 cases. As of this writing on March 18th, there have been 121 deaths out of a total 7,047 cases.
That is a drop in the death rate from 2.96% to 1.72%.
This is encouraging, as the U.S. death rate so far has been
substantially lower than in China and even lower than France and the
U.K. There has been much talk about policy responses to stem the spread
of COVID-19, but school closings and social distancing should mostly
affect growth in the number of cases, not the deadliness of the disease
itself.
Why would the U.S. death rate fall so much over just a few days? The
answer is that as more people are tested for the virus, the death rate
falls because it becomes more accurate.
And the most accurate data are likely coming from Germany, which
arguably has had better testing than any other country. Germany also has
the lowest death rate, at just over 0.1%. If that number sounds
familiar, it is roughly the death rate from the 2018-19 flu season in
the U.S.
So why is the death rate in Germany so low, and why is it falling in
the U.S., exactly? The answer is simple arithmetic. If only people who
are hospitalized or very sick get tested, then the denominator – the
number of COVID-19 cases – will be biased downward. Those with milder
symptoms or no symptoms will not be counted, and the virus will appear
more deadly than it really is.
For a clear explanation of the illusions created by incomplete data,
and the clarity provided by an accurate denominator, see this from OurWorldinData.
This is surely the case in China and Italy, but it is also likely
true in France, the U.K., and even in the U.S. currently. But if testing
is more widespread and rapid, then officials get a more accurate
estimate of the true death rate. It may be true that quicker, more
comprehensive testing can reduce the spread of the disease by allowing
for more effective quarantines, but again, that should not make the
virus less deadly to those who already have it.
In other words, while Germany is a relatively rich, healthy country,
there is no reason why its death rate from COVID-19 should be a fraction
of what it is in other similarly rich, healthy countries. What differs
is measurement. And part of the reason testing was more effective in
Germany is that it was decentralized. Independent labs have been doing
the testing, without the direction of a central bureaucracy.
A recent New York Times article
highlights this trend and attributes the lower death rate in Germany to
better testing, but by a different mechanism; treatment improves when
doctors know what they are dealing with:
“Unlike in other countries, where
national laboratories had a monopoly on testing, Germany’s distributed
system helped doctors to swiftly determine whether suspected cases
actually involved the new virus or a common cold, which can have similar
symptoms.”
It surely helped in Germany, but it is hard to believe that doctors
in Seattle or New York treating patients with a fever or cough right now
are not erring on the side of caution. What is surely true is that by
testing more people more quickly, Germany has much more accurately
measured the number of COVID-19 cases, which most countries are
under-stating.
Final note: the latest numbers in the US point to a continued drop in the death rate as testing accelerates.
This is good news This also means that we don't need to prolong closing everything down for months on end, and crashing the economy, because in short weeks, sensible precautions will see this whole thing finished, and no more precautions are needed than for any other sort of illness, such as seasonal flu. Common sense, yes, but shutting down everything? Not needed.
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