Explanation of results of Corona Covid-19 laboratory test for antibodies
Explanation of result SARS-Coronavirus-2 (SARS-CoV-2) Elisa test Blood value test.
Two types of antibodies can be tested for this test. The IgA antibodies occur first. The IgG antibodies arise later after the infection (after about 4 weeks).
SARS-Coronavirus-2 (SARS-CoV-2) IgA ELISA
- You are not infected with the coronavirus or you have not (yet) produced antibodies if the ratio is lower than0.8.
- If your result is between 0.8 and 1.1 the result is borderline worthy
- With a measured value higher or equal to 1.1 the contamination is positive.
SARS-Coronavirus-2 (SARS-CoV-2) IgG ELISA
- If the result of the IgG antibodies is below 0.8, no antibodies against COVID-19 are formed (yet).
- If the ratio is between 0.8 and 1.1. the result is borderline worthy
- If the measured value is equal to or above 1.1, the result is positive. You have formed antibodies against corona.
Since antibodies to SARS-CoV-2 are detectable at the earliest 10-21 days after the onset of symptoms, genomic detection (PCR from throat swab) is recommended for early diagnosis. PCR stands for Polymerase Chain Reaction, this test looks directly for the presence of genetic material of the SARS-CoV-2 virus. This test is not provided by Bloodtesting.nl Test. For this test you have to go to your doctor or GGD. See also the blog: How can you test for coronavirus?
Example result no antibodies IgA and IgG:
Sample result but IgG antibodies:
example results: IgA and IgG antibodies positive:
What is known so far about immunity to the new coronavirus:
In general, people are not protected for life with lung viruses, but only for a few years.
Gaining immunity is not just about antibodies. The immune system is also about teaching cells to ward off the virus. Much research is still being done into this cellular defence against the coronavirus. From September 2021, a test will be available that can visualise this memory cell defence: https://www.bloodtesting.nl/covid-19-t-cellen-geheugencellen.html.
It seems that the mild variant of the coronavirus also makes fewer antibodies. This may be because the body itself is more resistant to viruses and it does not need so many antibodies. It may also be that the mild variant was not serious enough to produce antibodies.
Mice and monkeys do not appear to be able to be infected a second time by SARS-CoV-2 and therefore cannot re-infect COVID-19. There is still no evidence of reinfection after the demonstration of antibodies
At the moment, there is still a lot of uncertainty about the new corona virus. Having antibodies does not mean that you cannot transmit the virus. You should therefore follow the guidelines of the RIVM. If you have enough antibodies it seems that you cannot get sick again, or much less. However, it is not yet clear how long the antibodies remain in the blood with this new virus.
As soon as more information and scientific studies are available, you will read about it here.
Findings from practice to date;
1. If the IgA is increased but there is no increase in IgG, this usually indicates a cross-reaction to another (corona) virus. However, there are also people who have an increased IgA. And then get sick 3 days later. Having antibodies says nothing about being contagious, for this a PCR test has to be done.
2. People who do have IgA antibodies, but have not yet developed an IgG antibody are advised to do a check-up in 1-2 weeks to see whether there has been any seroconversion. The IgG antibodies are then usually still converted from negative to positive.
3. IgA antibodies can be formed 2-4 weeks after the first symptoms of illness.
More information on tests or post tests that can be done within 5 days after receiving the blood at the lab can be found here
Here you see that first the IgM antibodies, then the IgA and only then the IgG antibodies appear, but also stay on the longest.
The graphs show the average height after the first day of symptoms:
Do you have antibodies against corona? Then through plasma donation, medication against covid-19 can be made.
For your general practitioner: Dutch Journal of Medicine Clinical significance of laboratory tests SARS-CoV-2, read here this article from 05-06-2020
Press release dated May 5, 2020: The EUROIMMUN Anti-SARS-CoV-2ELISA (IgG) has a specificity of 99% and a sensitivity of 100% after 21 days from the onset of symptoms: