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Covid 19 virus
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NiHaoMike:

--- Quote from: nctnico on March 30, 2020, 12:37:50 pm ---True. I have found this graph together with a test (but these are sold to doctors only) showing the concentration of anti-bodies versus time.




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That would also explain what appears to be patients getting reinfected shortly after seeming to have recovered, even though experts consider that highly unlikely. (Testing errors, of course, can also explain it.)
Cerebus:

--- Quote from: bd139 on March 30, 2020, 12:13:05 pm ---Apparently we’re going to be able to buy self test kits here on amazon soon.

Just a point to note on these: they may not be effective until 2-4 weeks after the symptoms subside. I can’t find the article I read to link to at the moment. Worth checking though.

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Depends on which kind of antibody type it is designed to detect. For our purposes we're only interested in immunoglobulin M (IgM) and immunoglobulin G (IgG).

IgM forms rapidly during an infection, IgG comes along a bit later. Eventually both types ramp up to the sort of levels that could be detected by an ELISA test. After an infection circulating levels of IgM fall. IgG level may continue to peak after an infection and then start to fall. Both types of antibody persist to some extent after an infection and form part of the 'memory' of the immune system. Eventually the IgG levels will be higher than the IgM levels.  IgG tends to be very antigen specific, some IgM may respond to antigens other than the antigen they are specific to - indeed IgM has been observed to respond to antigens that a host has never been exposed to.

So, an IgM detecting test is good for detecting a recent infection, not so good for one in the past. It may be a bit non-specific - so it's good for telling you if someone will have an immune response to a disease, not so good for telling you if they have actually had a specific disease.

An IgG based test is nice and specific, but won't show results as soon as an IgM based test would.

So, it's all going to depend on how a particular test has been formulated as to: How soon after infection it will give results, how specific it is to the viral strain that it is testing against. Becuase of this you should most definately thoroughly read the specific instructions on the specific test you have if you manage to get hold of one. If the instructions are in Chinglish, lord help you.

No ELISA field test is going to be sensitive enough to detect an infection before it has largely or completely run its course. ELISA tests are finicky and are quite difficult to make simultaneously sensitive, reliable and robust enough for use outside laboratory conditions.
thinkfat:

--- Quote from: bd139 on March 30, 2020, 12:13:05 pm ---Apparently we’re going to be able to buy self test kits here on amazon soon.

Just a point to note on these: they may not be effective until 2-4 weeks after the symptoms subside. I can’t find the article I read to link to at the moment. Worth checking though.

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The self tests are "lateral flow" tests. They're not very sensitive, but cheap. The ELISA tests being rolled out now over here are lab tests. You provide a blood sample and get a result a few days later. For early diagnoses, the PCR tests are still the only option.
Nusa:
This is US-specific, with state-by-state forecasts, but I found it very interesting. Note the disclaimer in the write-up that it is "predicated on the enactment of social distancing measures in all states that have not done so already within the next week".

http://www.healthdata.org/research-article/forecasting-covid-19-impact-hospital-bed-days-icu-days-ventilator-days-and-deaths
edavid:

--- Quote from: thinkfat on March 30, 2020, 01:58:26 pm ---The self tests are "lateral flow" tests. They're not very sensitive, but cheap. The ELISA tests being rolled out now over here are lab tests. You provide a blood sample and get a result a few days later. For early diagnoses, the PCR tests are still the only option.

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The self tests that were briefly sold here in the US (before the FDA shut them down) are just self collection tests, where you mail the sample to a lab for a PCR test.  I think those will be available before lateral flow tests.

I've read that Cepheid sells some of their PCR test cartridges for around $10, so PCR tests can be pretty cheap.

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