Are the CV tests really accurate?

[thyme4change]

Anyone else struggling with this?

There are so many cases that are totally asymptomatic and people only find out because they take the test for fun and amusement.

There are a bunch of people who have been very sick, with Covid symptoms, but are testing negative.

This is so easily contagious that we have to hold our breath if we leave the house, but so many people who test positive live with people who continually test negative - even when they show symptoms.

Either this is a super weird virus, or there is a flaw in our testing.

I googled "How accurate are Covid tests" and all the results basically say "We don't know."

I know nothing about medical testing, and I'm not proposing some conspiracy theory. I just can't get my head wrapped around such bizarre and inconsistent results. I know viruses aren't subject to human logic, but it is just so odd.

Any thoughts?

[Deleted]

Those folks in trump's entourage who test positive and don't get sick. Are they really positive or are the tests they're taking not reliable. Does this mean that trump, who doesn't wear a mask, could be positive and not even know it (and give it to others)?

[thyme4change]

Jul 10, 2020 15:44:09 GMT -5 @missrigby said:

Yeah. Thoughts: maybe trump really isn't testing negative and only thinks he is.

Maybe he tested positive, but being asymptomatic, he decided to not let that info out.

Which goes back to my original question....why are so many people testing positive and don't even feel tired, while other people describe agony and a myriad of terrible symptoms.

[Deleted]

I had to edit that because it was too snarky even for me. But...are there people testing negative who are sick but think they don't have the virus?  Who's to know?

[Deleted]

Thyme, that's a really good question.  I do not know how the various tests are crafted.  A medical friend told me that some test forms have a minimum floor beneath which they will show negative, and that the result will depend on how long since exposure and how much virus load you have developed.  

Add in the fact that some folks may be highly resistant to the virus, and who knows?  

[Deleted]

I keep hearing about how frequent testing is part of the plans to open schools. How does that happen when most people who are sick still can't get a test and if they do the results are taking weeks?

[The Walk of the Penguin Mich]

You have 2 issues....

The first is that if you swab where there is no virus, you get a negative test.  One scientist on tv describes it as going fishing.  If you do not catch any fish, it doesn’t mean that there are no fish...just you are fishing in the wrong area.

Secondly, if you do not have a sufficient viral load, you might get a false negative.

This is for testing for the virus.  The antibody test has a whole bunch of other issues.

[anciana]

Jul 10, 2020 16:18:33 GMT -5 The Walk of the Penguin Mich said:

You have 2 issues....

The first is that if you swab where there is no virus, you get a negative test.  One scientist on tv describes it as going fishing.  If you do not catch any fish, it doesn’t mean that there are no fish...just you are fishing in the wrong area.

Secondly, if you do not have a sufficient viral load, you might get a false negative.

This is for testing for the virus.  The antibody test has a whole bunch of other issues.

How about an antigen test in serum? Is the virus present in the blood at all to be detected there? I understand we would still have the problem of the "fishing in the underpopulated lake" so to speak.

[The Walk of the Penguin Mich]

Jul 10, 2020 16:31:59 GMT -5 anciana said:

Jul 10, 2020 16:18:33 GMT -5 The Walk of the Penguin Mich said:

You have 2 issues....

The first is that if you swab where there is no virus, you get a negative test.  One scientist on tv describes it as going fishing.  If you do not catch any fish, it doesn’t mean that there are no fish...just you are fishing in the wrong area.

Secondly, if you do not have a sufficient viral load, you might get a false negative.

This is for testing for the virus.  The antibody test has a whole bunch of other issues.

How about an antigen test in serum? Is the virus present in the blood at all to be detected there? I understand we would still have the problem of the "fishing in the underpopulated lake" so to speak.

I don’t believe that they have looked for the virus antigen in the blood.  To do this, they’d probably have to run a western blot.   Fishing in the blood would have a detection limit. 

The one advantage of the RT-PCR that they do for virus testing is that if the virus is there, you amplify the RNA so you can get a clear signal.  You cannot do this looking for a protein.  

[lurkyloo]

There are a few serum antigen (not antibody) tests on the market, I want to say the first one was approved May 9?  I haven’t heard a lot about them being deployed though.

The widely used tests look for viral RNA and they are very sensitive, they can detect something like 10 copies of RNA.  However, a positive test for viral RNA is not the same thing as confirmation of infectious material.  So it’s presumptive proof that you have been infected but not necessarily that you are still infectious (probably, but not for sure.).  Confirmation of infectious material requires demonstrating that the material you recover is capable of infecting cells in culture, which is labor and equipment intensive and not usually done.

If desired they can look at the number of cycles it takes to amplify the RNA and get an idea of how much the started with (strong vs weak positive) but that information is not typically reported to the patient.

False negatives are a big problem.  Swabbing in the wrong part of the nasopharynx, swabbing the nasopharynx when the infection is primarily in the lungs or the gastroenterocytes, sample mishandling, etc.  One of the papers I read said the gold standard was bronchioalveolar lavage (wash out the lungs) and test that fluid.  Again, not practical.

If you get a negative PCR result but have the symptoms, I’d take it with a large grain of salt and isolate anyway.  It’s not worth the risk of infecting others.

[lurkyloo]

Our babysitters father got covid and I suspect she was infected too-she had headaches and gastrointestinal symptoms.  We told her not to get tested bc I expected the bulk of the virus was GI and a nasal swab wouldn’t show anything and we wouldn’t trust a negative to be a real negative.

[Deleted]

Jul 10, 2020 15:38:08 GMT -5 thyme4change said:

Anyone else struggling with this?

There are so many cases that are totally asymptomatic and people only find out because they take the test for fun and amusement.

There are a bunch of people who have been very sick, with Covid symptoms, but are testing negative.

This is so easily contagious that we have to hold our breath if we leave the house, but so many people who test positive live with people who continually test negative - even when they show symptoms.

Either this is a super weird virus, or there is a flaw in our testing.

I googled "How accurate are Covid tests" and all the results basically say "We don't know."

I know nothing about medical testing, and I'm not proposing some conspiracy theory. I just can't get my head wrapped around such bizarre and inconsistent results. I know viruses aren't subject to human logic, but it is just so odd.

Any thoughts?

I’ve wondered about this myself. One of my coworkers that tested positive said her only symptom was shortness of breath. As in, even in a normal conversation, she’d have to stop talking and try to catch her breath, but it never got bad enough that she needed to be hospitalized. But her husband, who she never stopped sleeping in the same bed with, and her daughter and grandchild that lives with them, all tested negative and they never had any symptoms.

Did her family just have super duper immune systems or what?

To my uneducated brain, this does seem to be a “super weird virus”, or..... I’m not sure what *my* “or” is.

[giramomma]

Jul 10, 2020 17:03:49 GMT -5 @pinkcshmere said:

I’ve wondered about this myself. One of my coworkers that tested positive said her only symptom was shortness of breath. As in, even in a normal conversation, she’d have to stop talking and try to catch her breath, but it never got bad enough that she needed to be hospitalized. But her husband, who she never stopped sleeping in the same bed with, and her daughter and grandchild that lives with them, all tested negative and they never had any symptoms.

Did her family just have super duper immune systems or what?

To my uneducated brain, this does seem to be a “super weird virus”, or..... I’m not sure what *my* “or” is.

 While not the same,

When Miss M was 5 weeks old-

DS came down with the flu, strep, and some weird virus. Flu was confirmed through a test.

DD1 came down with strep and the virus

DD2 came down with the virus

Miss M and DH remained completely healhty.

I got a little sick, but it wasn't strep, flu, or the virus.

We think what happened is that DD2 brought the weird virus home from her grade, and between getting that and strep (strep was going around his floor at school), DS's immune system was weakened enough that he got the flu.

That said DD1 and DD2 have been sharing a room for the past 5 years or so. I don't know why DD2 didn't get strep.

[The Walk of the Penguin Mich]

Jul 10, 2020 17:03:49 GMT -5 @pinkcshmere said:

Jul 10, 2020 15:38:08 GMT -5 thyme4change said:

Anyone else struggling with this?

There are so many cases that are totally asymptomatic and people only find out because they take the test for fun and amusement.

There are a bunch of people who have been very sick, with Covid symptoms, but are testing negative.

This is so easily contagious that we have to hold our breath if we leave the house, but so many people who test positive live with people who continually test negative - even when they show symptoms.

Either this is a super weird virus, or there is a flaw in our testing.

I googled "How accurate are Covid tests" and all the results basically say "We don't know."

I know nothing about medical testing, and I'm not proposing some conspiracy theory. I just can't get my head wrapped around such bizarre and inconsistent results. I know viruses aren't subject to human logic, but it is just so odd.

Any thoughts?

I’ve wondered about this myself. One of my coworkers that tested positive said her only symptom was shortness of breath. As in, even in a normal conversation, she’d have to stop talking and try to catch her breath, but it never got bad enough that she needed to be hospitalized. But her husband, who she never stopped sleeping in the same bed with, and her daughter and grandchild that lives with them, all tested negative and they never had any symptoms.

Did her family just have super duper immune systems or what?

To my uneducated brain, this does seem to be a “super weird virus”, or..... I’m not sure what *my* “or” is.

Hard to know why.  Did the family members have an exposure to another coronavirus?  Blood type?  Better non specific immunity?  Your coworker not a spreader?  Your coworker not have a heavy viral load?  

There are still a lot of things that they just do not know.  

[pulmonarymd]

All test have false positive and false negative results. This is why tests are always confirmatory, and diagnoses do not rest only on tests. Lurkyloo gave a good explanation. You have sampling problems, and then the tests have their limits. A symptomatic patient with a positive test has the disease. A patient with typical symptoms and a negative test in an area with a high prevalence of infection, likely has the disease and a false negative result. Who knows about the asymptomatic positives, but if they can spread the disease like it appears they can, they are infected, and not sick, and a major problem.

All infectious diseases have a variable curse, some people get deathly ill, some appear to get mild symptoms. It is inexplicable at present, but has to do with factors too numerous to list here. Ths disease jumped from another species, so we do not know enough about it, so we have no idea why it does what it does in the body.

You also have to realize that identifying the cause of an infection can be difficult. In people who have severe sepsis, in many studies, the causative agent is found only 50% of the time. Same thing for pneumonia. You are asking for certainty when we cannot accomplish it with things we understand well.

[bobosensei]

Jul 10, 2020 17:11:59 GMT -5 giramomma said:

Jul 10, 2020 17:03:49 GMT -5 @pinkcshmere said:

I’ve wondered about this myself. One of my coworkers that tested positive said her only symptom was shortness of breath. As in, even in a normal conversation, she’d have to stop talking and try to catch her breath, but it never got bad enough that she needed to be hospitalized. But her husband, who she never stopped sleeping in the same bed with, and her daughter and grandchild that lives with them, all tested negative and they never had any symptoms.

Did her family just have super duper immune systems or what?

To my uneducated brain, this does seem to be a “super weird virus”, or..... I’m not sure what *my* “or” is.

 While not the same,

When Miss M was 5 weeks old-

DS came down with the flu, strep, and some weird virus. Flu was confirmed through a test.

DD1 came down with strep and the virus

DD2 came down with the virus

Miss M and DH remained completely healhty.

I got a little sick, but it wasn't strep, flu, or the virus.

We think what happened is that DD2 brought the weird virus home from her grade, and between getting that and strep (strep was going around his floor at school), DS's immune system was weakened enough that he got the flu.

That said DD1 and DD2 have been sharing a room for the past 5 years or so. I don't know why DD2 didn't get strep.

I grew up with 3 siblings.  Shared a room with 2 siblings until I was 7 or 8, and shared with the 1 sibling until I was almost 15.  2 of my siblings were prone to strep and ear infections.  While I shared a room I always lived with at least one of the ones that was prone to being sick.  I have only been prescribed antibiotics for a non tooth related infection one time in my life when I was really young maybe 6 or 7 and apparently had bronchitis.  But I remember not feeling sick, but thinking it was amazing that I got to take medicine that tasted like bubblegum.  I think it was amoxicillin.  I don't know if the doctor gave me antibiotics because two of my siblings were prescribed them (it could have been all 3) or not.  So I was either able to live with people that were always sick while I stayed well, or I was getting sick and not displaying/feeling symptoms.

I will say as far as my dental problems go I never know I have an issue until the infection is so bad that I need a root canal, and I've had 5.

[TheOtherMe]

My sister was asymptomatic when she was tested.  She now has symptoms and she is not doubting the test results.

The county health nurse told her that she and BIL should sleep in separate rooms and use separate bathrooms.  Given their attitudes toward covid, I was surprised that they are actually doing this.

My guess is BIL is getting exposed every day and is the most likely to catch covid from her.  I am not a doctor, but it makes sense to me.

All the family members who have been tested have tested negative.  I now have had two negatives in two weeks.

When we were kids, my sister got strep and tonsilitis several times a winter.  I have never had either strep or tonsilitis.

We both had measles, mumps and chicken pox.  She was much sicker with each disease than I was.

That was the main reason I was quite concerned when she tested positive for covid.

[movingforward]

Jul 10, 2020 18:29:47 GMT -5 TheOtherMe said:

My sister was asymptomatic when she was tested.  She now has symptoms and she is not doubting the test results.

The county health nurse told her that she and BIL should sleep in separate rooms and use separate bathrooms.  Given their attitudes toward covid, I was surprised that they are actually doing this.

My guess is BIL is getting exposed every day and is the most likely to catch covid from her.  I am not a doctor, but it makes sense to me.

All the family members who have been tested have tested negative.  I now have had two negatives in two weeks.

When we were kids, my sister got strep and tonsilitis several times a winter.  I have never had either strep or tonsilitis.

We both had measles, mumps and chicken pox.  She was much sicker with each disease than I was.

That was the main reason I was quite concerned when she tested positive for covid.

Just out of curiosity, does your sister know how she contracted the virus?

[Deleted]

There is no way we can isolate in our house, in a grand total of 1300 sq. ft.   We have one shared bathroom and one shared bedroom.  We have been incredibly blessed to have friends who brought masks and hand sanitizer so I could go out for groceries, and equally blessed with a friend that offered TP.  

[TheOtherMe]

movingforward  She says she does not know.  She was out and about buying groceries and going shopping.  She swears she wore a mask.

Covid is in the school system here and she knows lots of teachers.  Two of her teacher friends have it.  That is the most likely explanation.  

It sounds like her husband has it, but he said he isn't getting tested again.