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We are being inundated with questions regarding COVID-19 antibody testing (blood test) and "Immunity Passports".
- This is an evolving science but to understand the potential benefits we must understand the theories and the limitations...
THREAD:
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- This is an evolving science but to understand the potential benefits we must understand the theories and the limitations...
THREAD:
1/n
When our body mounts a defense against an infectious pathogen we develop neutralizing proteins called "Immunoglobulins" (IgM provide acute protection, IgG provide chronic and (hopefully) long lasting immunity)
2/n
2/n
T-cells provide another level of immunity by directly killing virus-infected human cells...hence their nickname "Killer T-cells" ...they 'come back' when we get re-exposed
- these guys are primarily responsible for the "cytokine storm" causing much of the COVID mortality
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- these guys are primarily responsible for the "cytokine storm" causing much of the COVID mortality
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As of today, the CDC has an antibody test that is NOT commercially available, testing IgG to a specific Sars-CoV-2 protein, the "spike antigen"
- The CDC test is only being used for epidemiologic and tracking purposes, it is NOT available to communities at this time
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- The CDC test is only being used for epidemiologic and tracking purposes, it is NOT available to communities at this time
4/n
- The CDC test reportedly has specificity > 99% and a sensitivity of 96%
* Specificity (test doesn't detect non target viruses)
* Sensitivity (true positive rate)
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* Specificity (test doesn't detect non target viruses)
* Sensitivity (true positive rate)
5/n
The FDA has verified and allowed 10 tests under a formal Emergency-use Authorization (EUA) while close to 150 are being marketed directly to customers without any review (unknown quality)
- can we trust corporations to do the right thing without proof of quality?
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- can we trust corporations to do the right thing without proof of quality?
6/n
The science is far from settled on what the meaning of a positive test implies regarding protection from future infection.
- There is strong concern that these tests may give patients a false sense of security if they test (+)...we just don't know yet
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- There is strong concern that these tests may give patients a false sense of security if they test (+)...we just don't know yet
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From WHO "Some governments have suggested that the detection of antibodies could serve as the basis for an "immunity passport" or "risk-free certificate" that would enable individuals to travel or to return to work assuming that they are protected against re infection...
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... There is currently no evidence that people who have recovered from COVID 19 and have antibodies, are protected from a 2nd infection.
- Tests must accurately distinguish between past infections from Sars-CoV-2 and those caused by the known set of 6 human Coronaviruses
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- Tests must accurately distinguish between past infections from Sars-CoV-2 and those caused by the known set of 6 human Coronaviruses
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...4 of these cause the common cold and circulate widely, the remaining 2 cause MERS and SARS
- At this early point in the pandemic there is not enough evidence about the effectiveness of antibody-mediated immunity to guarantee the accuracy of "Immunity Passports"
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- At this early point in the pandemic there is not enough evidence about the effectiveness of antibody-mediated immunity to guarantee the accuracy of "Immunity Passports"
10/n
... People who assume they are immune to a 2nd infection may ignore public health advice. The use of such certificates may therefore increase the risks of continued transmission.
- Certainly the HOPE is strong for a test to prove lasting immunity...we must KNOW it does
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- Certainly the HOPE is strong for a test to prove lasting immunity...we must KNOW it does
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Don't confuse blood tests with increasing availability of Naso-pharygeal swab testing (sensitivity <70% even when collected properly - often it is not)... swab testing has been jokingly compared to a brain biopsy...
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12/n
Summary: As of today there is no personal value to getting yourself checked for antibodies to the virus, as the results are unable to be reliably interpreted
- That information WILL be coming, just as the tests WILL improve
We need to begin nationwide #TestTraceIsolate
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- That information WILL be coming, just as the tests WILL improve
We need to begin nationwide #TestTraceIsolate
13/n
