
Relationship between the ABO Blood Group and the Covid-19 Susceptibility - car
https://www.medrxiv.org/content/10.1101/2020.03.11.20031096v1
======
Amorymeltzer
Some quick points:

\- Reported odds ratios[0] of 1.2 for A and 0.67 for O.

\- This is a preprint, so it has not been peer reviewed.

\- They compared blood type of patients with that of the general population in
the region.

\- Data is from 2,173 patients at three hospitals. The data varied between
them, but Wuhan had the overwhelming majority (1,775, or 81%) of cases.

\- Since these are all patients, they presumably are weighted toward the more
extreme responses. There were minimal age and gender differences, though.

\- A similar response for type O was apparently reported for SARS.

0:
[https://en.wikipedia.org/wiki/Odds_ratio](https://en.wikipedia.org/wiki/Odds_ratio)

~~~
graeme
Did they list an odds ratio for having a severe/critical case?

~~~
Amorymeltzer
No, they didn't look at severity. They did report ABO distributions for 206
deaths in Wuhan, which could be considered a proxy for severity but likely has
a lot of confounding variables, such age, wealth, etc. Those data were in-line
with the top-line results, but that's a small sample.

~~~
usrusr
They are looking at data from hospitals, so I'd expect mild cases to be
excluded.

Semantic nuances seem to be very relevant to the applicability (or not) of
this selection to the exact wording of the result: is a SARS-CoV-2 infection
that remains harmless because it is overcome before spreading from throat to
lungs classified as a light case of Covid-19 or is that label reserved for
more serious forms of infection?

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Taniwha
Because this is the next thing you're going look up:

[https://en.wikipedia.org/wiki/Blood_type_distribution_by_cou...](https://en.wikipedia.org/wiki/Blood_type_distribution_by_country)

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jakozaur
Not as dramatic difference as the title suggests... Pulling numbers from the
article.

3694 Control (Wuhan area)

A: 1188 (32.16%)

B: 920 (24.90%)

AB: 336 (9.10%)

O: 1250 (33.84%)

COVID-19 1888 patients

A: 715 (37.87%)

B: 494 (26.17%)

AB: 193 (10.22%)

O: 486 (25.74%)

The difference may be related to triaging criteria. E.g. different ethnic
groups overrepresented in given hospital.

~~~
car
I’d be happy to change the title, though it is basically quoted from the
article conclusion.

Not peer reviewed, but an interesting observation nevertheless. There will be
more data soon.

~~~
toptal
Given the fact SARS had a similar profile, this should be a reasonable
assumption.

I’m not saying it’s at the same standard as being peer reviewed, though it’s
more likely than not that the conclusions from this data will remain true
based on both the data and the correlation.

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umut
This has no more value than being a "fun fact" (sorry for the word 'fun' in
the context of a pandemic and death numbers).. a) it is something you don't
have any control b) the diff (odds, bayes factor or any similar definition) is
not that great to have an effect on public policy (something like, let's focus
our resources on region A, since region B has less risk kind of change)

So, let's all enjoy this study as food for our curiosity, and move on with all
the usual measures of social distancing, extra hygiene control and all..
Especially dangerous, if even one crazy person goes out because he has a
certain blood type and helps the disease spread

~~~
crimsonalucard
no, it means type O can do riskier jobs.

~~~
JoeAltmaier
Because they have 1/3 less chance of death? Not enough difference to convince
me (I'm O+)

~~~
crimsonalucard
Of course not. But when you're knee deep in the situation and it's time to
draw straws it's good to know risk tolerance. (I'm O-).

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necovek
Assuming the equal distribution of homo- and heterozygotes, it looks like the
numbers (A/AB +20%, B +3%, 0 -33%) _suggest_ the following:

• 00 (homozygote 0, but that's the only way someone is a 0) is at -33%
"chance" of catching SARS-Cov-2

• B0 (heterozygote B) is at -10%

• BB (homozygote B) is at +5%

• AB (well, heterozygote, obviously) is at +20%

• A0 (heterozygote A) is at <17%

• AA (homozygote A) is at ~33%

Basically, the hypothesis would be that presence of an A allele contributes
significantly to increased risk (~17%), B is mostly neutral (+1-2%), a 0
allele contributes to decreased risk (-17%).

Considering the distribution in healthy individuals (I haven't run the numbers
but only used roughly 30% for each group except AB which is at 10% — I've only
done the math in my head so I am way more off than that, and it would be quite
unlikely for the effect to be so linear as my breakdown above suggests) from
the study, everything roughly lines up.

It would be interesting if a study could confirm that, but they'd need parents
blood types for every individual to be able to get that.

I've seen mention of open data sets that include research articles, but is
there any data set to look at? It would be quite interesting since the
distribution of blood types supposedly differs strongly among "ethnicities" if
[https://www.livescience.com/36559-common-blood-type-
donation...](https://www.livescience.com/36559-common-blood-type-
donation.html) is to be trusted — their "Asian" number for AB is also at 7%
compared to 9% in their "health population" number.

If there was data just documenting whatever findings there are for patients,
it would help in independent "researchers" find correlations that might not be
obvious to others.

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shekharshan
I am a little rusty on my probability basics now but I was trying to remember
how one would go about answering the following question regarding Wuhan
numbers cited in this study:

"Given a person has type A blood type, what is the probability of that person
having covid19"

I remember this being something like P(E1 intersection E2)/P(E2) where E2 =
event that a person has type A blood and E1 = event that the person has
covid19.

In case of Wuhan 32.16% of the population has type A blood. So E2=0.3216. To
get E1 we would need total infections/total population for the city. We don't
have that number but is this thinking correct?

~~~
vitus
Yes.

In particular, as you describe it, you'd then need to solve for P(E1 ∩ E2) by
extrapolating from the existing result of P(E2 | E1) present in the article,
then plug it into that formula you've provided.

(Bayes' law streamlines the whole process by combining the two-step
calculation into one.)

edit: a slight nitpick: E2 is an event ("this person has type A blood"); P(E2)
is a number.

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hirenj
I recommend reading the review below on known effects of blood groups on
infection. Not super surprising in that blood group may have general effects.
I can't think how this would work mechanistically without knowing the glycans
on ACE2/TRMPSS2 or the spike, and if they carry antigen (I would expect not).

[https://www.ncbi.nlm.nih.gov/m/pubmed/26085552](https://www.ncbi.nlm.nih.gov/m/pubmed/26085552)

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mrfusion
How can blood type matter? What’s the mechanism of action?

~~~
hirenj
Excellent question!

Here's the answer: We have no idea!

Blood type antigens are complex carbohydrates, and A/B/O is the difference
between N-acetyl-Galactosamine/Galactose/nothing at the end of a sugar chain.

So let's talk about Coronavirus and sugars. SARS-COV-2 (and the prequel for
that matter) are relatively unique for viruses because they don't (as far as
we know) use sugars (sialic acids to be specific) to bind to cells, unlike all
of our other favourite viruses (e.g. influenza).

BUT that's not the only place it could matter. Maybe sugars help organise the
membrane to increase multivalent reactions, and there's some galectin that
binds to B antigen.

Or the virus itself somehow carries the antigen, and A/B protects against
furin processing?

Lots of possibilities. First thing I would check for is co-expression of ABO
with ACE2. If it's not in the same cells, then I have NO idea how it works.

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sdiq
Slight nitpick: I find the use of 'normal people' in the article a bit
distracting. I appreciate the fact that the authors are not native English
speakers but using 'the general population' was more appropriate here.
However, being a blood type 'O', I am not sure whether this consoles me.

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outlace
Assuming this result holds... Perhaps anti-A antibodies that may be produced
by non-A blood types have some cross-reactivity with the virus?

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Vysero
Well.. I don't know what blood type I am but it is somehow comforting to know
that there are at least some people out there who have a better chance at not
getting sick.

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david_draco
Odds ratios between 0.5 and 1.5 are not exactly considered strong evidence.
[https://en.wikipedia.org/wiki/Bayes_factor#Interpretation](https://en.wikipedia.org/wiki/Bayes_factor#Interpretation)

~~~
ced
If you're referring to the odds ratio between group A control and group B
covid, then that's not a Bayes factor AFAIK. A Bayes factor is to compare two
hypothesis. You can have an odds ratio of 1.00001 which is very significant
(eg. female/male birth ratio)

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mikorym
By the way (and not flamebaiting here) this is one of the reasons why "this is
natural selection" is the phrase that makes me the most angry in all of this.
Death by flu is selection for random shit that cause you to be better off
_against only one thing and that is: that exact desease causing strain_.

The worst thing about Covid 19 to me is how it selects against old people, and
even worse: Friendly, sociable old people.

~~~
robocat
Natural selection predominantly works before you breed.

There are some kin effects if elderly are killed, but natural selection
otherwise doesn’t apply much for the elderly.

~~~
PietdeVries
True! If it would, then male baldness would have been "natural de-selected" a
long time ago. But since men are getting bald mostly after they had their
offspring, partners (nature) cannot select on this...

~~~
rolltiide
women don't mind bald men, it's just different women. which can be hard to
accept.

bald _ing_ men on the other hand, not confidence inspiring.

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sub7
This has been circulating for a few days now. It's bogus.

There is absolutely 0 peer reviewed papers or double blind controlled studies
that prove this.

~~~
ComputerGuru
There are no double blind studies for anything covid just yet.

~~~
mnw21cam
There might be some slight ethical issues in performing double-blind studies
on covid infection susceptibility.

~~~
ComputerGuru
Right. But there are double blind studies now in progress on the effectiveness
of various treatments.

