When are which covid-19 tests possible? When can you see which antibodies?

At what point after the first symptoms of illness from COVID-19 or even before is it best to use what test?

It is becoming increasingly clear how the virus behaves and when in which way the infection is detectable.

One survey provides this picture:

Infection occurs in the first two weeks before the first symptoms of illness.

From 1 week before the first symptoms of illness, the virus is detectable via a throat/nose swab PCR test.

A few days before the first symptoms of illness, the virus is already detectable in the stool and there it remains visible for a very long time.

The virus in in saliva a little later detectable than through the throat-nose mucus, but also remains longer detectable through this route.

While in the nasal and throat mucus it is almost undetectable after only 3 weeks to 4 weeks.

The IgM and IgG antibodies show up almost equally in SARS-CoV-2, but the IgG antibodies remain visible much longer.

Up to this point, there is no end date to be given when the IgG antibodies to SARS-CoV-2 disappear because the disease has not been around for that long.

With SARS-CoV-1 this was 3 to 5 years. What having IgG antibodies says about immunity and whether disappearing antibodies means you are no longer immune is not yet known.

More and more is becoming known about antibodies to SARS-CoV-2.

Studies indicate when which types of antibodies are visible over time.

This graph shows how many days after the first symptoms of illness the IGM, IgA and IgG become apparent.

First, the IgM antibodies appear,

Then the IgA antibodies

and only later the IgG antibodies, but they do stay on the longest.

The study below indicates that the immune system starts producing IgM antibodies about 10 days after infection and that IgG antibodies emerge after 14 days.

Desiree

at 24 Nov 2020

Strange; the Diazyme study states that IgM production starts 10 days after the moment of infection while the Journal of American Medical Association states that IgM production only starts about 9 days after onset of symptoms. It is remarkable that the studies apparently differ so much in this respect; the difference is about 2 weeks. It is even stranger that the IgM antibodies in the first study have already disappeared after 21 days while in the other study they only emerge about the same number of days after the infection...

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Ellen van Gijsel

Retrieved from 29 Mar 2021

With such a new virus, it is important to monitor multiple studies until the common thread is clear.

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Freyer

Retrieved from 26 Mar 2021

You're talking about two studies with vastly different figures. One study says 10 days and the other study says nine days. You're making a difference of two weeks. 1 week has 7 days, two weeks 14 days. 10 days - 9 days is according to my math 1 day difference. So 9 days, could be 10 days, then I come up with : NO DIFFERENCE AT ALL????

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Jos van Putten

at 24 Oct 2020

Question about the results of a corona test: if I have "normal" flu and get tested for corona, will the result still be positive, even though I don't have corona? Can't believe that, but heard it from someone in one of the many corona conversations. This person claimed that among the corona infections that we see on TV every day, there are also the normal flu cases, but this is reported as a corona infection.

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Joke

at 25 Oct 2020

That's not true. Flu is caused by an influenza virus, Covid-19 by a coronavirus. They'll filter that difference out in a test.

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hugo

at 26 Oct 2020

Here is a nice example False positives, justified questions: in conversation with Rosanne https://youtu.be/ByWl3lNQKOU

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Freyer

Retrieved from 26 Mar 2021

That is indeed a very rare possibility, when someone puts his mouth mask on a table in a catering establishment and dead virus particles end up on the mask, which you then inhale later. At that moment, you can test positive anyway, but the blood result is negative. The PCR test itself that is used, only reacts to the SARS coronavirus type 2, not to other variants of corona. If you follow the conversation closely, you can feel between the pixels that it is a set up conversation, with someone who has never undergone a pcr test. If you follow the eyes, you can already see that the lady has learned a conversation by heart, of which she will roll her eyes in the direction of the learned memory and not in the direction of the memory where the experiences are. Too bad that not more people have these psychological insights, because then people would be able to unmask these criminals immediately.

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Janne

at 24 Feb 2021

Unbelievable what disinformation. Sad is the least of it.

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Marjan

at 29 Oct 2020

A conspiracy channel for the wappies. Just hilarious.

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hugo

at 26 Oct 2020

No, joke. They don't do that because they don't know if the person is sick because of an earlier corona contamination 'from which he or she didn't suffer at all' but because he or she now feels sick because of a flu they measure that this person is a carrier of an old corona virus which they still find in the body!

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Marjan

at 29 Oct 2020

I'd like to see a scientific source for this

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Hanneke

Retrieved from 27 Jan 2021

The first graph shows that a PCR test is likely to be positive in the first three weeks after the first symptoms of illness, whereas one is considered infectious only in the first week (or first two weeks in case of very severe course with hospitalization). In the fourth to sixth week after the first symptoms, the PCR test is probably negative, but this is not certain. So it is certainly possible for someone who happens to have the flu to test positive for corona due to a previous infection, but that does not mean the test will be positive due to the flu virus. In addition, there is still a very small proportion of false positives and not everyone who tests positive for the PCR is also infectious, as the test is very sensitive. The claim that you can test positive for corona with the flu is true if you take it literally, but that is not because of the flu but because of a recent corona infection or the very rare false positive test.

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