Understanding the covid test (serological, pcr, antigenic) of Sars-Cov2 (and its variants)

[pedrodelavega]

It seems that the antibodies detected by the PCR test disappear quite quickly. Some doctors claim that after only a few months (3 months) the antibodies could disappear ...
If this is confirmed, the reliability of the PCR test would therefore also be very relative.

PCR tests are not intended to measure the presence of antibodies but of viruses:

The tests virological (RT-PCR) can be used to determine if a person is a carrier of the virus at the time of the test by means of a nasal sample. It is the only reliable and recommended test for screening.
The tests serological can be used to find out if a person has developed an immune reaction after coming into contact with the virus. These tests detect the presence of antibodies through a blood test. Currently, this category of tests is still in the evaluation phase, in particular to determine their reliability and their ability to detect the existence of immunity against the virus. Pending the evaluation and validation of these elements, serological tests are not recommended for screening.
https://www.normandie.ars.sante.fr/coro ... s-de-tests

https://doctocare.com/depistage-covid-19/

[Christophe]

About rapid antigenic tests:

[Paul72]

Their study is interesting and confirms the concerns about these rapid tests.

However, we can say that directly detecting 60% of infected people who present themselves saves precious time on the epidemic, even if all the negatives must be tested so as not to miss the missing 40%, the PCR result sometimes taking several days to arrive.

So useful if used wisely and not just anywhere.

[Grelinette]

It dates a bit (August) but has this announcement to use trained dogs to detect the coronavirus been confirmed?
Trained and trained dogs would detect Covid19 on a wipe impregnated with the sweat of patients!
The reliability of the results would exceed 95% success. (Fake?)

http://www.academie-medecine.fr/test-ol ... entraines/

https://www.lci.fr/sante/video-des-chie ... 54585.html

https://www.francetvinfo.fr/sante/malad ... 18435.html

[Christophe]

About the new antigenic test VS PCR: https://www.has-sante.fr/upload/docs/ap ... ues_vd.pdf

Screenshot_2020-11-08 Quick review on antigenic detection tests for the SARS-CoV-2 virus - synthese_tests_antigeniques [...]. Png (265.61 KiB) Viewed 2417 times

So if I understood this table correctly, the antigen must be done BEFORE the PCR ...

[Paul72]

It is recommended beforehand if there is a risk of being already highly contagious (so with an already high enough viral load, and even minimal symptoms)

[Christophe]

https://www.lunion.fr/id206150/article/ ... e-de-covid

Why rapid tests failed in the face of second wave of Covid in Italy

(..)

Ideally, antigen testing should be supplemented with PCR testing
Anyone who tests positive for antigen in Italy is supposed to have a PCR test to confirm the result. But because rapid tests have an 80/90% accuracy level, infected people can fall through the cracks.

(..)

[ABC2019]

https://www.lunion.fr/id206150/article/2020-11-12/italie-pourquoi-les-tests-rapides-ont-echoue-face-la-deuxieme-vague-de-covid

Why rapid tests failed in the face of second wave of Covid in Italy

(..)

Ideally, antigen testing should be supplemented with PCR testing
Anyone who tests positive for antigen in Italy is supposed to have a PCR test to confirm the result. But because rapid tests have an 80/90% accuracy level, infected people can fall through the cracks.

(..)

the real problem is above all that probably between 50 and 80% of asymptomatic people do not get tested, we only get tested when we know we are in contact but in general it is because our contact has become symptomatic !

[Paul72]

https://www.lunion.fr/id206150/article/2020-11-12/italie-pourquoi-les-tests-rapides-ont-echoue-face-la-deuxieme-vague-de-covid

Why rapid tests failed in the face of second wave of Covid in Italy

(..)

Ideally, antigen testing should be supplemented with PCR testing
Anyone who tests positive for antigen in Italy is supposed to have a PCR test to confirm the result. But because rapid tests have an 80/90% accuracy level, infected people can fall through the cracks.

(..)

Oh no, they haven't understood anything !!!

It is when the test is negative that it should ideally be completed with a PCR !!!
If it's positive, it's positive, isolation. Point!

Moreover, the official circulars mention it (I had a piece of paper in front of me, for the hospital staff)

[Janic]

It is when the test is negative that it should ideally be completed with a PCR !!!
If it's positive, it's positive, isolation. Point!

Being positive doesn't mean anything else ... than being positive and that makes us feel good. being positive does not mean being sick, nor contaminating since the positive test does not come until after the battle. Or having antibodies would mean being contaminating. No one should then come into contact with anyone else [*] because if the barrier measures reduce contamination, they do not stop them, and this until all populations have achieved group immunity. in question. So in ... ?????
And a negative does not mean that in the hour which follows the individual will not be contaminated regardless of the precautions taken.
[*] and here we are again for the same circus as with AIDS!