
Why does the coronavirus spread so easily between people? - pseudolus
https://www.nature.com/articles/d41586-020-00660-x
======
bhanhfo
I upvoted this just because of the nature.com link - but after I actually read
it, I am disapointed. Summary:

Q: Why does the coronavirus spread so easily between people?

A: We don't know yet

The results presented not verified by experiments yet.

"But some researchers are cautious about overstating the role of the
activation site in helping the coronavirus to spread more easily. “We don’t
know if this is going to be a big deal or not,” says Jason McLellan, a
structural biologist at the University of Texas at Austin"

~~~
gzu
It's really not hard to grasp why it would spread quickly. This virus harbors
in the respiratory system of an infected patient. The viral infection invades
cells and releases more of the virus.

This is so contagious because:

1\. Everyone breaths in nearly 8000 liters of air each day

2\. Virus are so small that they stay suspended in air for a while, some
estimates are 30min (think how smoke stays afloat)

3\. We have no innate immunity to this novel virus

~~~
blowski
Article lists multiple leading experts working round the clock on this, all
saying they're not sure why the virus is so contagious.

But some random person of uncertain credentials says "It's really not hard to
grasp why it would spread quickly".

If you have some kind of expert credentials with serious evidence, then it
would be great to hear it. Otherwise your opinions are just unhelpful,
potentially dangerous noise - and the internet has no shortage of those
already.

~~~
gzu
These experts are looking for the biochemical proof of why it's so contagious.

That's not needed to make judgements on why this virus could be spread easily.

------
andruby
I encourage everyone who wants to stay up to date to follow the daily video
updates from Dr John Campbell. He’s a (semi) retired academic doctor who
specialises in respiratory diseases.

He looks at it from a scientific and pragmatic point of view, without typical
media hyperbole. He’ll often get info from doctors on the ground. He’s been
posting videos on COVID-19 since January.

[https://www.youtube.com/user/Campbellteaching/videos](https://www.youtube.com/user/Campbellteaching/videos)

~~~
everybodyknows
Another thread describes him as a retired nurse. Any pointers to his CV?

~~~
andruby
Both are true. He's a nurse with a doctorate. He actually address this in this
video:
[https://www.youtube.com/watch?v=AAwYFEcvvOc&t=170](https://www.youtube.com/watch?v=AAwYFEcvvOc&t=170)

------
DCKing
Question for a virologist, but does it actually spread so easily between
people? The article asks a loaded question, but is it "justifiably loaded"?

Given the background prevalence of influenza it might be hard to compare, but
does it actually spread more easily than influenza does? Is that a conclusion
we can already take? For sure it seems to be spreading faster than SARS did,
but I don't know if SARS was considered "easy" in this regard either.

~~~
thebruce87m
Are there any examples of Flu or anything else infecting a cruise ship in a
short time period? That was the thing that stood out the most to me.

~~~
alexpotato
Norovirus (aka food poisoning) can spread incredibly quickly and is the usual
example of "fast moving virus in isolated population".

e.g. [https://www.cbsnews.com/news/norovirus-outbreak-hits-
royal-c...](https://www.cbsnews.com/news/norovirus-outbreak-hits-royal-
caribbean-cruise-ship-277-people-sick-passengers-crew/)

~~~
war1025
Norovirus is the bane of my existence as a parent of 3 small children. One kid
throwing up? Great. Expect everyone in the family to have it within three or
four days.

------
achenatx
Most droplet born viruses are very contagious (e.g. efficiently infect a
target). It wouldnt surprise me if the covid-19 virus is so contagious because
symptoms are slow to develop.

SARS was effectively stopped because fever developed quickly so it could be
easily detected.

Rubeola, pertussis, and TB are all incredibly infectious (R0 > 10) because
they are truly airborne. They essentially can survive and still be very
infectious in a desiccated form that can float in the air for a long time.

Molecularly you can look at the ID 50 (infectious dose) required to start an
infection.

Epidemiologically speaking there can be broader causes like temperature
stability, length of illness, severity of illness, amount of virus production,
induction of coughing, etc etc.

My bet is on non molecular epidemiological reasons

~~~
mgleason_3
The endlessly bad/conflicting advice

\- dont wear masks, save them for the actual sick. For a disease most people
dont know they have and incubates for days seems like the advice should be
“wear a mask if you have a cough”.

\- dont cough on your clothing, cough into tissues, toss them and wash your
hands. This seems almost impossible given most people seem to cough multiple
times a minute. Why not teach them to contain the spray. Eg Best: Dont go out.
Next best: wear a mask. As a last restort, cough into your shirt (as in pull
the collar up over your mouth an cough down inside the shirt so the spray is
contained inside it).

~~~
bad_user
Masks are currently in short supply. At this point it's more important for
medical personnel to have access to masks, than it is for individuals. Because
if the hospitals get overwhelmed, we're all screwed — this being a classic
tragedy of the commons.

Also it's pretty hard to wear a mask correctly. I've seen plenty of people
wearing surgical masks with their nose out. If you aren't going to wear that
mask correctly, then what's the freaking point?

And even if you can train yourself to wear a mask correctly, to properly
dispose of it, etc, the price of masks, even surgical ones, has gone through
the roof and even if you can afford to wear a new one each day or two, the
supply of masks isn't reliable.

So I'm afraid that at this point, even if you have a cough, the best you can
do is to isolate yourself, because masks are in short supply and expensive.

------
xenonite
Impressive, a gene analysis shows that SARS-Cov2 is the first known SARS virus
that has genes for docking at furin activation sites. And furin sites are not
only in the lungs, but also in the liver and small intestines. This may
explain why there are actual cases with liver failures.

------
forkexec
It can likely survive up to 9 days on fomites (surfaces and objects), or
longer with low temperatures and high humidity.

[https://www.news-medical.net/news/20200211/Coronavirus-
can-l...](https://www.news-medical.net/news/20200211/Coronavirus-can-live-on-
common-surfaces-for-nine-days-how-to-kill-it.aspx)

which references:

[https://www.who.int/docs/default-
source/coronaviruse/situati...](https://www.who.int/docs/default-
source/coronaviruse/situation-
reports/20200211-sitrep-22-ncov.pdf?sfvrsn=fb6d49b1_2)

[https://www.journalofhospitalinfection.com/article/S0195-670...](https://www.journalofhospitalinfection.com/article/S0195-6701\(20\)30046-3/fulltext)

------
Alex3917
> Their experiments have shown that the spike protein binds to a receptor on
> human cells — known as angiotensin-converting enzyme 2 (ACE2) — at least ten
> times more tightly than does the spike protein in the SARS virus. Veesler’s
> team has also found this, which suggests that the receptor is another
> potential target for vaccines or therapies. For example, a drug that blocks
> the receptor might make it harder for coronavirus to enter cells.

First, let me say that although the government doesn't formally recognize me
as a doctor, I watch a lot of medical stuff on TikTok so I'm basically getting
my MD 7 seconds at a time.

That aside, this seems dubious to me; if anything it's likely better to take
ACE inhibitors now so that your body makes more ACE2 receptors before you get
the virus. One of the ways the virus kills people is by detroying their ACE2
receptors, which your lung cells need in order to function. Downregulating
them is unlikely to prevent the virus from getting into your cells, rather it
will just leave your cells with less healthy ones left over after the virus
destroys the ones it uses to enter your cells.

As evidence from this epidemic, smoking cigarettes upregulates your ACE2
receptors, and smokers are less likely to get serious illness from COVID-19.
Of course if they do get seriously ill then they're more likely to die, but
this is probably just because of the lung damage caused by smoking. At the
very least it seems irresponsible to put out a statement like this without
saying that all the available evidence currently points the opposite way, as
does the evidence from the SARS epidemic.

~~~
maayank
> and smokers are less likely to get serious illness from COVID-19.

Source? Genuinely interested

~~~
Alex3917
[https://www.reddit.com/r/COVID19/comments/fdb2g6/new_study_r...](https://www.reddit.com/r/COVID19/comments/fdb2g6/new_study_reports_only_578_patients_were_smokers/)

[https://www.reddit.com/r/COVID19/comments/fbodxp/study_finds...](https://www.reddit.com/r/COVID19/comments/fbodxp/study_finds_unexpected_age_distribution_and_rates/)

[https://www.reddit.com/r/COVID19/comments/f8wldm/unlike_appa...](https://www.reddit.com/r/COVID19/comments/f8wldm/unlike_apparently_sars_and_ncov2019_smoking_is_a/)

[https://www.reddit.com/r/COVID19/comments/ff06im/bulk_and_si...](https://www.reddit.com/r/COVID19/comments/ff06im/bulk_and_singlecell_transcriptomics_identify/)

~~~
ChrisAntaki
If a smoker does get it though, is it more severe?

> Consistent with earlier results, the few smokers who do get diagnosed sem to
> be more likely to progress to severe illness (3/5 vs ~1/5 expected).
> [https://www.reddit.com/r/COVID19/comments/fdb2g6/new_study_r...](https://www.reddit.com/r/COVID19/comments/fdb2g6/new_study_reports_only_578_patients_were_smokers/)

~~~
Alex3917
Yes, that's also what I said in my original comment.

------
ComputerGuru
Where can one obtain raw (anonymized) data on individual cases? Age, sex,
location, infection date, severity, outcome, resolution date? Preferably
machine readable?

Edit: thanks for the links, guys!

~~~
tantalor
That's still PII; you need to aggregate to actually anonymize.

~~~
ComputerGuru
Ok. The question still stands?

~~~
dekhn
it probably is not available to random folks on Hacker News. I doubt this sort
of information is being widely disseminated, with centralized collection, due
to the rapidly evolving nature of the epidemic, and, as mentioned, the PII
issues.

------
8bitsrule
I'm not a medical person, so I thought I'd pass this along ... information
from a major King Country hospital, _citing the CDC_ (and an eye-opener for me
... see site for more helpful details).

"1 person out of 200 people who are exposed to a COVID-19 positive individual,
will become COVID-19 positive (0.5% transmission rate in the general public)"

[https://www.evergreenhealth.com/coronavirus](https://www.evergreenhealth.com/coronavirus)

------
mistersquid
Very encouraging to see such deep analysis available to the general public.

As a layperson, I feel I know very little about how SARS-CoV-2 spreads from
person to person, especially given that asymptomatic persons are communicable.

~~~
mrandish
Just FYI, this is not "deep analysis".

If you really want to understand what's going on with CV19 you can try reading
the pre-print papers posted at www.reddit.com/r/COVID19 which is a heavily
moderated science-focused sub. The analyses posted by users down thread often
contain links to even more recent source data.

I've learned an enormous amount there (and also how inaccurate media headlines
can be in a complex, rapidly-evolving situation like this).

~~~
ComputerGuru
Linked: [https://reddit.com/r/COVID19](https://reddit.com/r/COVID19)

------
takeda
There doesn't seem to be statistics about how an enthicity affects the virus
spread and severity.

From reported cases it looks like certain communities are more endangered than
others.

~~~
rsynnott
> From reported cases it looks like certain communities are more endangered
> than others.

Italians?

I mean, this particular conspiracy theory never seemed at all plausible, but
it seems particularly non-plausible _now_.

~~~
takeda
Italians have custom to kiss when greeting people, that can increase the
spread.

~~~
usrusr
As far as I know Italy also has a hospital culture that is extremely open,
e.g. it is common for patients (non-ICU I guess) to get home-cooked meals
brought by friends and family instead of having a hospital meal. That means
that if there is community spread, the very weakest of the elderly, those
already hospitalized, will be more exposed than in countries where hospital
visits are less common. An extremely cynical view would be that this increases
deaths early on but frees up valuable beds for the peak of the wave. (It's
painful to just write this)

------
tus88
Because it's both CONTAGIOUS and highly INFECTIOUS.

