
Infected people without symptoms might be driving the spread of coronavirus - mgreg
https://www.cnn.com/2020/03/14/health/coronavirus-asymptomatic-spread/index.html
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astrophysician
Just FYI, if you don’t have symptoms or direct contact with someone with COVID
(basically if you don’t have a high probability of having COVID _before_ you
have the test) a positive test still probably means you don’t have COVID:

Sample numbers:

* Population of US: 3e8

* People that have COVID right now in the US: 1e5 (30x the confirmed cases right now)

* Disease rate: 3e-4

* FALSE POSITIVE RATE for COVID test: 1% (likely higher)

* TRUE POSITIVE RATE for COVID: 100% (definitely lower)

If you take the test, don’t have symptoms or direct contact, and then the test
comes back positive for the disease, then under these pretty reasonable
assumptions, the likelihood you have the disease is

P(actually have COVID| positive test) = 3e-4 /(1e-2(1-3e-4) +3e-4) = 2.9%

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arcanus
Whole this is a correct application of Bayes Rule, a risk adjusted perspective
still indicates that you should act as if you do have the virus. This is
because the probability of having the virus multiplied by the damage of an
infected person spreading the disease is much higher than the false positive
probability times the personal impact of self-quarantine.

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astrophysician
Yea I agree that it’s still useful like you say as just a way to screen for
“higher risk” individuals and have them isolate, but still food for thought.

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tartoran
I wish there were more testing kits available, I wouldn’t want to be a vector
of infection if I have no symptoms but am still carrying the virus. Im in the
US and testing kits are not a thing yet

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olliej
Testing kits aren’t a thing in the US unless you have symptoms _and_ can
demonstrate contact with a confirmed case. :-/

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olliej
I mean this is standard - almost every viral disease has a period where you’re
contagious (viral particles sloughing off), but Aren’t yet showing any
symptoms.

