
80% of people with Covid-19 are asymptomatic, China figures indicate - bookofjoe
https://www.bmj.com/content/369/bmj.m1375.abstract
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jimrandomh
There's a confusion that I'm seeing repeatedly, which is important to get
right:

Asymptomatic != Presymptomatic. If someone is asymptomatic at the moment you
test them, that could be either because they will never develop symptoms, _or_
it could mean that you tested them during the disease's incubation period.
When talking about a patient at a particular moment in time when you tested
them, both of these are referred to as being asymptomatic. When talking about
the overall disease course, the former case is called asymptomatic and the
latter is called presymptomatic.

As tests get better and less scarce, and contact tracing gets better, a larger
fraction of cases will be tested when they are presymptomatic. When
researchers do studies that screen a bunch of people, especially in
populations where the obviously-symptomatic people have mostly already been
moved elsewhere, they will find that most of their positives are asymptomatic
(at the time of test), and unless they're doing follow-ups, they don't know
whether they'll develop symptoms later.

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manfredo
The first sentence spells it out pretty explicitly:

> New evidence has emerged from China indicating that the large majority of
> coronavirus infections do not result in symptoms.

This is not far off from the figures I had preciously been seeing of 50-70% of
people never developing symptoms.

If this is antibody testing, then the people who test positive are already
immune to the virus (there's the question of whether different mutations can
result in repeated infections, but that's a bit of a tangent).

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canada_dry
... which is why instead of focusing only on a test for antibodies, science
should be trying to identify and detect the attributes that make someone
more/most susceptible to the worse symptoms of the virus (e.g. lung
infection).

If we were able to detect who is most susceptible - which it appears that >80%
of us are not - it would be another helpful tool in dealing with this
pandemic.

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twomoretime
We still don't know anything certain about the latent period of this virus. We
also don't know if it remains dormant after an immune response, though it is
not retroviral like HIV.

Still, this 80% asymptomatic condition could lull us into a false sense of
security, meanwhile there may be other peaks in the average latent period
distribution. In other words it may be that some people are asymptomatic for
weeks, months, years...Before flaring up and spreading.

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twomoretime
Too late to edit but this would explain the huge uncertainty in the dormancy
period, early reports were anywhere from 3 to 20 days, this was the range that
inspired the 14 day quarantine procedure.

But if 80% of cases are asymptomatic that could mean that all of the
underlying numbers are wrong given the continued lack of tests in many
countries including the US.

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kencausey
Does this include elevated temperature?

~~~
kencausey
To answer my own question I looked around and while it seems that a fever is
the most common symptom, it is not present in all cases where testing
indicates the presence of the virus.

