7 ms·

That's a Serological test and it only goes positive about 5 days from infection, by which time you're probably not that contagious. This is a nucleic acid test

That's a Serological test and it only goes positive about 5 days from infection, by which time you're probably not that contagious. This is a nucleic acid test which directly detects the virus and will be positive if you're contagious. They're complementary, but you need a molecular test to stop the spread. This will be a very good product.

nerfhammer 7y ago
would this tell you if you had the virus in the past and therefore have built immunities?
- JonathanFly 7y ago
  Yes, serology tests are antibody tests.
- jrockway 7y ago
  I think you need an antibody test for that, which apparently you can buy for $20 starting on 4/1 (there was an article about it on HN this week).
quietbritishjim 7y ago
I have also read that it takes between 7 and 14 days from infection until you start to show symptoms. From your comment that would mean that anyone showing symptoms is "probably not that contagious". Given the exclusion rules rules here in the UK that doesn't sound right. What piece is missing?
- akiselev 7y ago
  The onset of symptoms starts between 2 and 14 days after infection with 3 to 6 days being the average depending on the cohort. [1] Outliers exist, such as one patient that did not show symptoms for 27 days. It is unknown when a person becomes infectious, but so far data suggests that its days before symptoms appear for most patients and as many as two thirds may be completely asymptomatic. [1] https://www.worldometers.info/coronavirus/coronavirus-incubation-period/ https://www.worldometers.info/coronavirus/coronavirus-incuba...
neuro 7y ago
I am not an expert, but it clearly states in the link at the bottom it’s not a serology test, although they do offer a serology test strip with the meter too. https://finance.yahoo.com/news/decn-finalizes-fda-pre-eua-141500114.html https://finance.yahoo.com/news/decn-finalizes-fda-pre-eua-14...
DocSavage 7y ago
That’s not how the contagiousness works. Most reports have average of 5 days from infection to symptoms, but many people are asymptomatic or have mild symptoms. At least one study says viral shedding is close to peak the day before symptoms and the time course of shedding goes down over time. Saying you are probably not contagious just 5 days after infection is misinformation, especially since incubation can range from 2 to 14 days.
jessriedel 7y ago
I have no idea if the GenViro test is real/functional, but it does not claim to be a serological test. Nor is it PCR. It claims to harvest monoclonal antibodies from rats challenged with the virus, and then attaches those antibodies to the surface of an electrode in such a way that when the antibodies bind to the virus they change the electrical properties of the electrode.
- deleted 7y ago
  [deleted]
- jeremyjh 7y ago
  It still relies on a population of antibodies for detection. By the time you’ve built a good population of antibodies to trigger the test you will have been contagious for many days. This test is still very valuable though as confirmation of who has antibodies and is likely immune.
  - zenexer 7y ago
    The parent is saying that the antibodies used come from an external source, not from the patient. If what the parent is saying is true, why would the patient need antibodies?
- mbreese 7y ago
  That’s the opposite of what you’d want to do. You want to attach the antigen to a test and screen your body for immune cells with an antibody to the antigen. If you’re actively fighting the virus, you might see enough antigen to show a positive test. But that’s pretty iffy — especially if you’re trying to do this with a finger stick. There just isn’t enough blood to work with for most tests (see Theranos). The PCR tests require nasal or throat samples because that’s where the virus is most abundant (and accessible).
  - jessriedel 7y ago
    > That’s the opposite of what you’d want to do. You want to attach the antigen to a test and screen your body for immune cells with an antibody to the antigen No, that's a serological antibody test. They are useful, but they only work once your body has already mounted a response to the virus. In contrast, PCR tests looks for the actual viral RNA, and they work regardless of what your immune system is doing. In principle, the test I described could do likewise: it identifies the actual virus particles in the same way the (mouse) immune system does: by keying into them with antibodies which in turn trigger a larger response (the voltage).
ineedasername 7y ago
People show symptoms at 3 to 13 days. So, if the test is useful at 5+ days, then is should be fine for many/most sick people seeking treatment. Though yes, it would be very limited for prophylactic testing, as in testing all family/close contacts of a known infected person to see who might have caught the disease themselves.

nerfhammer 7y ago

would this tell you if you had the virus in the past and therefore have built immunities?

JonathanFly 7y ago
Yes, serology tests are antibody tests.
jrockway 7y ago
I think you need an antibody test for that, which apparently you can buy for $20 starting on 4/1 (there was an article about it on HN this week).

quietbritishjim 7y ago

I have also read that it takes between 7 and 14 days from infection until you start to show symptoms. From your comment that would mean that anyone showing symptoms is "probably not that contagious". Given the exclusion rules rules here in the UK that doesn't sound right. What piece is missing?

akiselev 7y ago
The onset of symptoms starts between 2 and 14 days after infection with 3 to 6 days being the average depending on the cohort. [1] Outliers exist, such as one patient that did not show symptoms for 27 days. It is unknown when a person becomes infectious, but so far data suggests that its days before symptoms appear for most patients and as many as two thirds may be completely asymptomatic. [1] https://www.worldometers.info/coronavirus/coronavirus-incubation-period/ https://www.worldometers.info/coronavirus/coronavirus-incuba...

neuro 7y ago

I am not an expert, but it clearly states in the link at the bottom it’s not a serology test, although they do offer a serology test strip with the meter too. https://finance.yahoo.com/news/decn-finalizes-fda-pre-eua-141500114.html https://finance.yahoo.com/news/decn-finalizes-fda-pre-eua-14...

DocSavage 7y ago

That’s not how the contagiousness works. Most reports have average of 5 days from infection to symptoms, but many people are asymptomatic or have mild symptoms. At least one study says viral shedding is close to peak the day before symptoms and the time course of shedding goes down over time. Saying you are probably not contagious just 5 days after infection is misinformation, especially since incubation can range from 2 to 14 days.

jessriedel 7y ago

I have no idea if the GenViro test is real/functional, but it does not claim to be a serological test. Nor is it PCR. It claims to harvest monoclonal antibodies from rats challenged with the virus, and then attaches those antibodies to the surface of an electrode in such a way that when the antibodies bind to the virus they change the electrical properties of the electrode.

deleted 7y ago
[deleted]
jeremyjh 7y ago
It still relies on a population of antibodies for detection. By the time you’ve built a good population of antibodies to trigger the test you will have been contagious for many days. This test is still very valuable though as confirmation of who has antibodies and is likely immune.
- zenexer 7y ago
  The parent is saying that the antibodies used come from an external source, not from the patient. If what the parent is saying is true, why would the patient need antibodies?
mbreese 7y ago
That’s the opposite of what you’d want to do. You want to attach the antigen to a test and screen your body for immune cells with an antibody to the antigen. If you’re actively fighting the virus, you might see enough antigen to show a positive test. But that’s pretty iffy — especially if you’re trying to do this with a finger stick. There just isn’t enough blood to work with for most tests (see Theranos). The PCR tests require nasal or throat samples because that’s where the virus is most abundant (and accessible).
- jessriedel 7y ago
  > That’s the opposite of what you’d want to do. You want to attach the antigen to a test and screen your body for immune cells with an antibody to the antigen No, that's a serological antibody test. They are useful, but they only work once your body has already mounted a response to the virus. In contrast, PCR tests looks for the actual viral RNA, and they work regardless of what your immune system is doing. In principle, the test I described could do likewise: it identifies the actual virus particles in the same way the (mouse) immune system does: by keying into them with antibodies which in turn trigger a larger response (the voltage).

ineedasername 7y ago

People show symptoms at 3 to 13 days. So, if the test is useful at 5+ days, then is should be fine for many/most sick people seeking treatment. Though yes, it would be very limited for prophylactic testing, as in testing all family/close contacts of a known infected person to see who might have caught the disease themselves.