
High Temperature and High Humidity Reduce the Transmission of Covid-19 - umeshunni
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3551767
======
Animats
But not by enough. This epidemic has a growth rate (R) of at least 2. The
article claims "One degree Celsius increase in temperature and one percent
increase in relative humidity lower R by 0.0383 and 0.0224, respectively." The
March to July difference for New York City is only 19C. San Francisco, 9C. For
both cities, humidity is relatively uniform year round.

Even assuming this result is meaningful, it still leaves an R way above 1.

~~~
dntbnmpls
> For both cities, humidity is relatively uniform year round.

There is no way humidity is relatively uniform year round in NYC. It gets very
humid during the summer and very dry during the winter.

~~~
valenciarose
The relative humidity in NYC does not vary much from 60-65%. Absolute humidity
is measured as grams water per cubic meter and is virtually never reported
because what is relevant to human comfort is evaporation.

Indoor humidity in the winter is generally low because increasing the
temperature without adding moisture is lowers relative humidy.

[https://weather-and-climate.com/average-monthly-Humidity-
per...](https://weather-and-climate.com/average-monthly-Humidity-perc,New-
York,United-States-of-America)

------
_-___________-_
I am eagerly awaiting more studies into this subject. Something doesn't feel
right about the relative lack of local transmission in e.g. Vietnam
(temperatures over 30C at least in the south right now) compared to e.g. Italy
(temperatures, what, 15C or lower in the north right now?).

Cambodia's extremely low case count can easily be explained away by them not
testing anyone, but Vietnam appears to be quite proactive with tracing and
testing, yet still has a relatively low count and minimal transmission.

~~~
realusername
Vietnam has taken this epidemics 10x more seriously than Italy, that could
just be the difference.

They are testing as much as they can, everybody who had contact with infected
people are tracked down and quarantined, streets where you had infected people
are closed down and disinfected, almost everybody wear masks, you have
temperature checks & hydroalcoholic gel available in public areas, schools are
fully closed since early January.

~~~
_-___________-_
Yes. However, there's also no travel restriction between Cambodia and Vietnam,
significant cross-border traffic, and Cambodia is not "taking it nearly as
seriously" as Vietnam is.

If Vietnam had the transmission going on that Italy does, the case-tracking
and quarantining would be a lot harder, and I just don't buy that the other
things (masks, forehead temperature checks[0], hand sanitizer that hardly
anyone knows how to use properly) have much of an impact.

There has to be some much larger factor than those at play (and this study
suggests what that factor could be).

[0] I encourage people to ask or look what the reading is when getting these
checks. About a third of the time when I get a forehead temperature check, the
reading is totally nonsensical, like 31C, but the person just waves me through
since it's under the threshold. I'm skeptical of the efficacy of a test that
is this inaccurate.

------
jclark_th
Another paper saying something similar

[https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3550308](https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3550308)

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filereaper
Really hoping this helps in India which so far has had really low reported
cases.

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glouwbug
Sure, but what about when it gets cold again? It may come back even worse

~~~
AnimalMuppet
By then, we should have enough testing kits, and authorities should be better
prepared to handle it.

~~~
Taek
Not to mention a better baseline immunity within the population, and more
preparedness as a whole.

Testing kit shortages, lack of information, no vaccine, etc. are all a
function of how little time we've had to respond. If we can buy 3 months,
that's a lot of bonus time to prepare.

~~~
jmnicolas
Europe had about 3 months compared to China and is handling the situation much
worse.

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chrisco255
Maybe that's why Singapore hasn't been badly impacted?

~~~
X6S1x6Okd1st
Singapore is included in how they determined this result, therefore you
shouldn't use this result to explain why singapore is doing better.

~~~
9nGQluzmnq3M
No, Singapore is not in China and is thus _not_ in the set of "100 Chinese
cities". It's only mentioned in the paper in graphs of temperature and
humidity of a whole bunch of countries.

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cVwEq
Here's the study on arxiv [1], if you're more inclined to use that system.

[1]
[https://arxiv.org/ftp/arxiv/papers/2003/2003.05003.pdf](https://arxiv.org/ftp/arxiv/papers/2003/2003.05003.pdf)

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forkexec
This isn't peer-reviewed.

Maybe I have bad information, but cold plus high humidity caused it to persist
on fomites longer (9+ days). Wouldn't heat plus low humidity be better than
heat plus high humidity? What is/are the breakdown mechanism(s)?

~~~
AstralStorm
High humidity reduces aerosol transmission, which is the more important
vector.

(By essentially washing down the vapor and additionally making people exhale
less water. At least that's the theory behind it.)

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farseer
Spain seems to be an exception to this theory.

~~~
tomerico
Madrid has cold weather up until Tuesday -
[https://www.accuweather.com/en/es/madrid/308526/march-
weathe...](https://www.accuweather.com/en/es/madrid/308526/march-
weather/308526)

It’d be interesting to see if the warmer weather since Tuesday will reduce the
number of new cases. If we assume a week between exposure to getting
diagnosed, we would start seeing lowering rate of new infection starting from
mid next week.

~~~
baby
23C, thought it would be warmer now, what about Thailand?

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notmyname259
I checked with a bunch of biologists and all of them find the results here to
be merely correlational and misleading. Have asked to wait for more evidence

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procinct
Excuse my ignorance but would a colder temperature but with rain help prevent
due to the high humidity or does it require heat AND humidity?

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bamboozled
In the developed world a lot of people spend time indoors with air
conditioning most of the summer anyway? Especially more frequently now thanks
to climate change. Not sure how this changes a lot once it’s circulating
already?

------
known
Taiwan is doing good in containing Covid-19 despite its proximity to China

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Leary
Looking at figure 4 in the paper gives me some comfort since the majority of
the population centers in the northern hemisphere could approach a R of 1 in
July.

------
_bxg1
This sounds great, but I don't know anything about SSRN. Can someone shed
light on the credibility here?

~~~
neural_thing
same as arxiv

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inamberclad
Have the authors considered increased sunlight/UV radiation in warmer areas?

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gcc_programmer
105 data points (patient pairs). Linear regression. Not conclusive.

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xxpor
To be pedantic, COVID-19 is the disease, SARS-CoV-2 is the virus. It's like
HIV vs AIDS.

~~~
taneq
If you reduce the transmission of the virus, do you not reduce the
transmission of the disease?

~~~
xxpor
I mean, that's why it's pedantic.

Technically you can't "transmit" the disease. The disease consists of the
effects on the body.

Also, you can transmit the virus without having the disease, which is what
makes it dangerous since you have no idea. It's like you can transmit HIV
without having AIDS for years:

>Acquired immunodeficiency syndrome (AIDS) is defined in terms of either a
CD4+ T cell count below 200 cells per µL or the occurrence of specific
diseases in association with an HIV infection

That doesn't happen for a long time (or today, for a lot of people, never).

~~~
taneq
Well, fair. My assessment was based on the assumption that the distribution of
outcomes for a patient isn't affected by the source of the infection. If you
had some hypothetical way of transmitting the virus only to hosts who would
then develop symptoms of the disease, I guess you could argue that you could
reduce transmissions of the virus while maintaining transmissions of the
disease.

That'd be _impressively_ evil though.

------
KKKKkkkk1
This study fits a two-variable linear model to a high-dimensional nonlinear
process.

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ak39
Exactly how does one take this body of scientific knowledge and act on it?

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serioussecurity
this abjectly fails to deal with heteroscedasticity

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graycat
How is the virus doing in Singapore, an island on the equator?

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svscam
Here's a likely related paper from 2007:

[https://jvi.asm.org/content/82/4/1899](https://jvi.asm.org/content/82/4/1899)

 _In this study, a human immunodeficiency virus (HIV)-based pseudovirus system
was employed to address these issues. Our results indicated that the SL-CoV S
protein is unable to use ACE2 proteins of different species for cell entry and
that SARS-CoV S protein also failed to bind the ACE2 molecule of the horseshoe
bat, Rhinolophus pearsonii. However, when the RBD of SL-CoV S was replaced
with that from the SARS-CoV S, the hybrid S protein was able to use the huACE2
for cell entry, implying that the SL-CoV S proteins are structurally and
functionally very similar to the SARS-CoV S. These results suggest that
although the SL-CoVs discovered in bats so far are unlikely to infect humans
using ACE2 as a receptor, it remains to be seen whether they are able to use
other surface molecules of certain human cell types to gain entry. It is also
conceivable that these viruses may become infectious to humans if they undergo
N-terminal sequence variation, for example, through recombination with other
CoVs, which in turn might lead to a productive interaction with ACE2 or other
surface proteins on human cells._

Look at the authors:

 _Zhengli Shi_

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

 _She is a researcher at the Wuhan Institute of Virology (WIV), which is part
of the Chinese Academy of Sciences (CAS). Shi and her colleague Cui Jie found
that the SARS virus originated in bats._

~~~
tn890
Can someone with a better understanding of molecular biology and virology
explain what this means? I don't want to jump to conclusions.

~~~
nate_meurer
The paper describes how virologists in Wuhan engineered a "SARS-like" virus --
previously limited only to bats -- specifically to make it infective in humans
via the ACE2 receptor. That's the same receptor used by the SARS-CoV-2 bug
we're fighting now.

Note that the paper was submitted 12 years ago. They've had a lot of time to
work out the kinks, if they were so inclined.

EDIT:

I want to repeat what I've said in other comments, because what I initially
said was inaccurate. These researchers didn't actually create a new
coronavirus, but rather a much simpler and safer virus purpose-built to test
some receptor-binding structures.

This is a well-established way to study viruses safely, and this kind of work
is critical if we're to learn how to develop vaccines faster in response to
epidemics.

~~~
echelon
Why on earth would they do this? What sort of application does this have or
serve?

If it's a bioweapon, why was it published?

Is there any concrete genetic or documented evidence to show COVID-19 is
engineered? This is a big claim and has severe ramifications for China, if
true.

~~~
nate_meurer
According to the paper, they did it in order to figure out why SARS-CoV was
able to infect humans, while numerous other SARS-like viruses are not. Their
hyposthesis was that the critical feature is a particular sequence in the
protein found on the "spike" that the virus uses to bind to host receptors. By
constructing a new SARS-like virus with the desired spike protein, they were
able to validate that hypothesis.

It seems to me that if there was any malign intent behind this work, they
would not have published a paper on it. Obviously, that's doesn't preclude the
possibility of an accidental release from the same lab twelve years later. As
far as I know, there's no way to prove whether 2019's coronavirus was
engineered in any way.

~~~
nate_meurer
I want to repeat what I've said in other comments, because what I initially
said was inaccurate. These researchers didn't actually create a new
coronavirus, but rather a much simpler and safer virus purpose-built to test
some receptor-binding structures. This is a well-established way to study
viruses safely.

This kind of work is critical if we're to learn how to develop vaccines faster
in response to epidemics.

------
sb057
The ME in MERS stands for Middle East, since outbreaks of it are always from
camels. Such places are some of the hottest on the planet. MERS is another
form of coronavirus.

It is foolhardy to think spring and summer weather will save us.

~~~
robjan
It's a related but different virus. Also, the environment in the Middle East
tends to be arid.

