Case Fatality Rate (CFR) for COVID-19

00:00 This is the change in CFR from January to February, in parts of China.

00:06 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.

00:20 In Hubei province, the same trend was observed, but in that sense it was a bit of the opposite going on though.

00:28 It started out low, went to a low peak and then descended afterwards.

00:35 The rest of China, it started about 5%, then came down and plateaud at about 1% or so.

00:42 In China overall, followed the same trend as Wuhan.

00:46 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.

01:01 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.

01:12 Here are some examples of initial CFRs in various parts of the world for COVID-19.

01:18 So in the world, we see it started out low, then rose quickly.

01:23 In Europe, a similar trend.

01:25 In the United States, it started high, came down, then came up again.

01:29 In China, as we just saw, it started low, then went to a peak, then came down and so forth.

01:37 The lesson from this curve, these curves rather, is that CFR is unstable earlier on in the epidemic.

01:46 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.

02:02 I mentioned that age is important as well.

02:05 So for COVID-19, let's look at some of the CFRs in different parts of the world as distributed by age.

02:12 South Korea, we see that lethality increases dramatically as we get into the later years.

02:20 Same as Spain, same with China and of course, same with Italy.

02:24 The lesson from this graph is that as noted, the death rates for COVID-19 are extremely gated by age, but also by geography.

02:37 So these are multi-variable analyses.

02:40 It matters where you live, it matters how old you are.

02:43 It matters how many comorbidities you have and so forth.

02:49 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.

02:59 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.

03:12 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.