
Adjusted Age-Specific Case Fatality Ratio During for COVID-19 in Hubei [pdf] - tomerbd
https://www.medrxiv.org/content/10.1101/2020.03.04.20031104v1.full.pdf
======
svara
This model is nice in principle, but its results depend crucially on what is
ultimately an educated guess of the reporting rate of symptomatic cases.

This parameter can be found experimentally by testing for antibodies against
the virus in a random sample of the population. This has not been done so far.
As long as that's true, CFR estimates will be quite uncertain.

Also really interesting in this context is how Germany is looking more and
more like a huge outlier in terms of fatality. Almost 1000 cases and 0 deaths
so far. Sure, that may still change, but the outbreak has been going on for a
while there already.

~~~
not_a_moth
Or look at S Korea, 7313 cases 50 deaths, .68% CFR. Would like to see the age
group breakdown.

If I had to guess why CFR is so much lower in S Korea, it's because they tend
to test more widely, ie. don't only test when patients show up at the hospital
with severe symptoms. Or in other words they are closer to the real CFR.

~~~
lifthrasiir
> Or look at S Korea, 7313 cases 50 deaths, .68% CFR. Would like to see the
> age group breakdown.

As of 2020-03-08 0:00 AM UTC+9 [1]:

    
    
                  Patients        Deaths
        Age       (% of total)    (% in group)
        
        80+        212  (3.0%)      14  (6.6%)
        70--79     409  (5.7%)      18  (4.4%)
        60--69     878 (12.3%)      11  (1.3%)
        50--59    1349 (18.9%)       5  (0.4%)
        40--49     975 (13.7%)       1  (0.1%)
        30--39     760 (10.7%)       1  (0.1%)
        20--29    2133 (29.9%)       0  (0.0%)
        10--19     360  (5.0%)       0  (0.0%)
        0--9        58  (0.8%)       0  (0.0%)
        
        Total     7134              50  (0.7%)
    

[1]
[https://is.cdc.go.kr/upload_comm/syview/doc.html?fn=15836441...](https://is.cdc.go.kr/upload_comm/syview/doc.html?fn=158364414115900.pdf&rs=/upload_comm/docu/0015/)
(p. 10)

~~~
lern_too_spel
Most of Korea's cases were discovered since late February and have not had a
chance to either recover or die (i.e., the numerator is right-censored).
Expect the CFR to rise there.

~~~
Fjolsvith
Or not. What about all the infected people who haven't had symptoms serious
enough to warrant seeing a doctor and getting tested positive for Coronavirus?

~~~
lern_too_spel
That is a constant factor on the denominator, which is lower in Korea than
elsewhere due to the availability of 10-minute drive-through tests. The factor
on the numerator will be much higher at the start of an epidemic and go down
to 1 when it completes.

The estimated average time to die for those who die from COVID-19 is 28 days.
28 days ago, Korea had fewer than 50 cases total.

~~~
alexilliamson
How is the number of mild, untested cases a constant factor? If less serious
patients start to get tested more frequently, this number will change.

~~~
lern_too_spel
> If less serious patients start to get tested more frequently, this number
> will change.

If everyone were tested, the denominator goes up by some constant factor. In
Korea, people are already being tested at the first sign of cold symptoms.

------
chrononaut
How much do we think healthcare and hospital stability was implicitly factored
into this study given that the data was focused in Hubei? Meaning, if
hospitals had to turn away patients, one would think the death rate would
increase. If hospitals could receive all patients, one would presume the death
rate would be lower? It's clear health care systems get overloaded even with a
low symptomatic case saturation per capita.[0]

Related to this, what I haven't seen mentioned or discussed extensively is not
only would the fatality rate increase for Covid-19 cases if hospitals are
overloaded, but I would assume the fatality rate for _all other needs_ of a
hospital would also increase. Does anyone know this has been assessed? (e.g.,
did Hubei see a notable increase in non-Covid-19 related deaths during this
period?)

[0] [https://www.aljazeera.com/news/2020/03/coronavirus-wreaks-
ha...](https://www.aljazeera.com/news/2020/03/coronavirus-wreaks-havoc-italy-
tests-limits-health-system-200307112350888.html)

~~~
DocSavage
I think we're seeing a small case study of this in the nursing home in
Washington. Out of 120 residents, 13 are dead and have been identified with
COVID-19. There were 11 more who died at the nursing home since Feb 19 and
haven't been tested, but they said on average 3-6 residents die per month. I
think the nursing home scenario is probably a worst case given both age and
underlying health concerns (unlike elderly still living in their own home or
with their families). Given the Seattle area medical infrastructure, this
fatality rate can't be explained by overloading of our facilities.

I really disliked Fauci's comments that "the risk is low" to the American
population, pointing to the rate of infection. He hedges this with some hand
waving that it could change at any moment. I thought it was irresponsible to
say the risk is low when they hadn't done any real testing and we've actually
got outbreaks like in Kirkland. Regarding his comment that the WHO fatality
rate is too high because of asymptomatic population and the denominator in
reality is much higher. Fine. But he doesn't acknowledge that the numerator
might be much higher as well. How many 80+ year olds, especially those with
preexisting conditions, die and are assumed to have just passed from old age
and the preexisting conditions. It is a characteristic of this virus that the
people getting killed are the most likely ones not to raise huge red flags
early. So in general, I would've preferred him to not say anything about risk
until we actually get more numbers and real testing within our population. The
average fatality rate hides the fact that this virus is very dangerous to the
elderly.

~~~
bluedino
Nursing homes and other long-term care units also have the lowest quality of
care and staff ratings in the industry. Typically plagued by overstaffing,
unhappy workers, etc.

------
d4t4
This study makes a comparison of the age distribution in reported Covid-19
cases vs. the distribution of ages in the Chinese population. I think this
approach can definitely provide insight however, there’s one assumption that
this study uses which will definitely bias the fatality rates being estimated.

> We chose to fix to 100% the reporting rate of infected individuals that have
> symptoms and are aged 80 and more, and estimate the reporting rates in other
> age groups relatively to that of older individuals. If further data, coming
> from a study in the general population, shows that this assumption is
> violated, this would lead to an overestimation of the CFR in our study.

I find it hard to believe that 100% of cases in individuals over 80 will be
reported. It seems like any estimation of fatality rate at this time is going
to be guesswork without more systematic sampling of the population.

I’m not trying to minimize the danger of Covid-19. It seems like caution to
prevent further spread is absolutely necessary.

------
mhb
Presumably age as a factor is used because it's easy to measure, but it would
be nice to know the effect of comorbidity. For example, comparing otherwise
healthy 60 year olds to otherwise healthy 30 year olds.

~~~
bob33212
And a breakdown into specific medical factors. Diabetes, Smoker, AIDS, cancer,
flu.

------
SubiculumCode
So all our presidential candidates (sitting or otherwise) have some relatively
bad odds.

~~~
dougmwne
Iran's leadership is experiencing this right now.

------
Gys
> We estimated the age-specific case fatality ratio (CFR) by fitting a
> transmission model to data from China, accounting for underreporting of
> cases and the time delay to death. Overall CFR among all infections was 1.6%
> (1.4-1.8%) and increased considerably for the elderly, highlighting the
> expected burden for populations with further expansion of the COVID-19
> epidemic around the globe.

~~~
wbhart
It's worth pointing out that this is the CFR for the virus, SARS-CoV-2 (i.e.
including asymptomatic individuals). The CFR for the disease, COVID-19, is
3.3% (2.9-3.8%).

I'm not sure which it is more common to report, but the 2% estimate that was
used earlier in the epidemic was for the disease rather than the virus,
apparently.

~~~
poizan42
The CFR rate for the disease rather than infectius agent is not really useful
for anything besides inciting panic. Consider the case where a virus only
shows symptoms in 0.1% of case, but is 100% fatal when it does. You could
report this as NEW EPIDEMIC 100% FATAL, WE ARE ALL GONNA DIE!!! but that
hardly gives a realistic picture.

~~~
wbhart
"We are all gonna die" is a statement about the mortality rate, not the case
fatality rate. This paper does not deal with the mortality rate.

------
watertom
Until the dust settles on COVID-19 this is all speculation.

I have a question about the Spanish Flu.

Most reliable literature CDC, WHO lost the CFR for the Spanish Flu at 2.5.
This makes no sense to me.

The Spanish flu killed between 50-100 Million people, 3-6% of the world’s
population, it infected about 500 Million people, so why isn’t the CFR between
10-20%?

~~~
maxerickson
How does the proximate cause of death factor into the CFR? In 1918, most of
the deaths were from secondary infections:

[https://www.nih.gov/news-events/news-releases/bacterial-
pneu...](https://www.nih.gov/news-events/news-releases/bacterial-pneumonia-
caused-most-deaths-1918-influenza-pandemic)

------
longtimegoogler
As someone who is atopic but not asthmatic, I am especially concerned. My
guess is that atopic and asthmatic indivdiduals might be at higher risk.

As someone in their forties, I can't think of any other potential risk that I
am aware of where I might have a 1 in 50 chance of dying if I catch this
(assuming an elevated risk) given that I am relatively health otherwise.

------
portlander12345
Do we have enough information to do this kind estimate for serious or critical
symptoms, rather than just deaths? What are the chances of somebody in a given
age bracket needing breathing support?

------
vackosar
Death rate: Age 0-9: 0.0094% Age 10-19: 0.022% Age 20-29: 0.091% Age 30-39:
0.18% Age 40-49: 0.4% Age 50-59: 1.3% Age 60-69: 4.6% Age 70-79: 9.8% Age 80+:
18%

TL;DR dont infect ur parents as 60-69 has 1 in 21 chance of death.

~~~
lordnacho
These numbers may look insignificant but your base chance of dying in a given
year is on a similar order. Have a google for life tables, the UK ones are
available online.

For younger people, it's like having a fair part of a year's worth of life
risk, for older people several years.

Do you want that risk for no benefit? There's also whatever problems you get
that don't kill you. I suspect you waste a good few weeks of your life
regardless of whether you survive.

~~~
conistonwater
Do you have a link for that? The first result I got is this life table for US
2003 on Wikipedia
([https://upload.wikimedia.org/wikipedia/commons/4/47/Excerpt_...](https://upload.wikimedia.org/wikipedia/commons/4/47/Excerpt_from_CDC_2003_Table_1.pdf)),
and the risk for an average 60 year old is around 1% per year. Do you mean to
say 1% and 4.6% are on a similar order?

~~~
lordnacho
Of magnitude, yes. This is not the one I found yesterday but figures are
similar.

[https://www.ons.gov.uk/peoplepopulationandcommunity/birthsde...](https://www.ons.gov.uk/peoplepopulationandcommunity/birthsdeathsandmarriages/lifeexpectancies/datasets/nationallifetablesunitedkingdomreferencetables)

~~~
conistonwater
That's not reasonable. 1% risk of death vs (1+4.6)% risk of death (a) is
closer to 1 order of magnitude higher (log_10(5.6)=0.75), and (b) 1%/year and
5.6%/year are nowhere near the same the way most normal people think about the
risk of dying.

A 1 order of magnitude _lower_ risk (0.1%) is basically negligible, like a
regular flu. On the other hand, a 1 order of magnitude increase, i.e., around
10% risk of dying would already rate among the deadliest epidemics in history,
and far above things like the Spanish flu, so comparing orders of magnitude is
just not the right way to think about this number.

~~~
lordnacho
You might have a point there. But I think a lot depends on the error of the
disease estimates, and it seems clear that they could well overlap with the
range of natural death rates. Dependent on how you slice and dice it.

For sure old people are at at least a year's risk.

------
DataDrivenMD
As with any statistical analysis based on a sample of the total population,
there will be biases (as many have already noted). That being said, these
results reflect what we’ve seen in the real world in places like Washington
state, Italy, Iran, and even S. Korea. More to the point: these data
underscore the importance of following the advice of public health officials.

It’s fine to have an intellectual discussion about the merits of the study,
but let’s make sure that we keep our eye on the prize. Each of us has a
responsibility to do our part in protecting our parents, friends, and
coworkers.

TL;DR - This study suggests that many of us on HN will be fine no matter what.
But it also demonstrates that, if left unchecked, it’s possible (if not
probable) that many of us will be grieving the loss of someone we love.
There’s no need to panic, and there’s no room for those who seek to be
dismissive, flippant, or ignorant. Everyone will be fine if each of us focuses
on doing the right thing.

------
acoderhasnoname
why is the CDC not telling us where are the suspected cases and how many out
there??? Do they even know that number??

------
kaiabwpdjqn
Death rates aside, it looks like younger people are less likely to even get
the disease (not especially surprising). If you exclude the really young
people, even the 30 year olds would likely be under represented (I think). One
implication of this may be that societies with more socially engaged older
people will be more vulnerable to this. E.g. countries where people who serve
as frequent touch points to strangers like frontline retail jobs are likely to
be older might do worse in this circumstance.

~~~
paulryanrogers
Are we sure they don't get it, or are just asymptomatic in the short term.

Chicken pox is a thing parents commonly seek out for their kids around here.
But in the long term the vaccine is still better at reducing long term
consequences.

(Got it intentionally as a child then again [unintentionally] as a teen. Had
some nerve damage since. Not looking forward to shingles.)

~~~
kaiabwpdjqn
That was my point of confusion on the charts for symptomatic people. I’m
assuming that the relatively high rates of non symptomatic individuals implies
they’re testing people without symptoms in a somewhat random sample style

