This is the change in CFR from
January to February, in parts of China.
So, in Wuhan, where COVID-19 was first
discovered, its CFR started out quite high,
over 20% and went down
to under 5% rather quickly.
In Hubei province, the same trend
but in that sense it was a bit
of the opposite going on though.
It started out low, went to a low
peak and then descended afterwards.
The rest of China, it started about 5%, then
came down and plateaud at about 1% or so.
In China overall, followed the same trend as Wuhan.
The point here is that CFR starts out
high as we test the most symptomatic cases,
and then levels off to a lower level
when testing becomes more commonplace.
As a result, we have to be very careful in how
we interpret the CFR earlier on in an epidemic
because testing is still ramping up.
Here are some examples of initial CFRs
in various parts of the world for COVID-19.
So in the world, we see it
started out low, then rose quickly.
In Europe, a similar trend.
In the United States, it started high,
came down, then came up again.
In China, as we just saw, it started low, then
went to a peak, then came down and so forth.
The lesson from this curve, these curves rather,
is that CFR is unstable earlier on in the epidemic.
So we have to wait, we have to
give it some time, to collect more data
to allow testing to be deployed on
a more even and distributed basis
before we get a true sense of
how lethal the disease actually is.
I mentioned that age is important as well.
So for COVID-19, let's look at some of
the CFRs in different parts of the world
as distributed by age.
South Korea, we see that lethality increases
dramatically as we get into the later years.
Same as Spain, same with China
and of course, same with Italy.
The lesson from this graph is that as noted,
the death rates for COVID-19
are extremely gated by age,
but also by geography.
So these are multi-variable analyses.
It matters where you live,
it matters how old you are.
It matters how many
comorbidities you have and so forth.
Now, if I tell you that the
CFR for COVID-19 is about 3%,
well that's an average of all the
ages of people who got the disease.
But if your population skews
older as does the population of Italy,
more so than the population of the
USA, chances are you'll have a higher CFR
because you'remore likely to die
if you're older.
So stratifying lethality rates by age
category is sometimes a useful thing to do,
especially for determining patient
prognosis, but also in understanding
the impact of the disease on your population.