Much is not yet known about the coronavirus, including the duration of immunity after an infection. The question confuses many, from scientists to ordinary people, who would like to know to what extent they are protected after the first dose of the vaccine.
Some questions may be answered yes by antibody testing, but even that doesn't give a complete answer when it comes to immunity.
There are two main types: tests that measure the presence of an antibody in the body and others that investigate in what measures these antibodies are deactivating against the virus.
The former are very reliable if you want to determine if you have Covid-19. Others, known as neutralization tests, are conducted so that the blood serum in the lab comes into contact with parts of the coronavirus to determine what the accuracy of the antibody is.
“Although no test provides absolute safety, it can be said that 'a positive neutralization test almost always means that you are protected, '" said Thomas Lorenz, a German medical biochemist.
“And with a large amount of antibody, there is a certain uncertainty”
And immunologist Carsten Wackl points out that neutralization tests are more accurate, but also adds that studies have shown a correlation between the amount of antibody and the amount of neutralizing antibodies.
"In other words, if you have very high levels of an antibody in your blood, it's unlikely that all of these antibodies are targeting the wrong part of the virus," Wackle said.
This means that a simple antibody test indicates a certain degree of protection, but can't tell you exactly how much.
Actually, no one can tell you what kind of Mary you're really immune to. Even with a large amount of antibody, there is a certain level of uncertainty, " Wakl says.
The price of the tests varies from country to country. In most European countries, the price is about twenty EVR, while the other type of test is more expensive and ranges between 50 and 90 EVR.
Home tests can also be obtained in some countries, but Lorenz advises against these " Do-it-yourself” interrogations.
What types of antibody are there?
Three types of antibody are particularly interesting. "Fast-acting forces" against viruses - IgA and IgM antitela. They accumulate quickly, but their level decreases faster after the end of the infection than the third type of antibody. These are IgG antibodies, i.e. "memory cells “that can remain in the body for a long time and can be" established " that Sars-CoV-2 is the enemy.
"Those with these memory cells can quickly create new antibodies when needed," Vacl explains.
When does it make sense to test for antibodies?
The body begins to produce IgG antibodies only a few days after the start of the infection, and therefore testing for this type of antibody should wait at least two weeks after infection.
On the other hand, tests for IgM antibodies within a few weeks of infection can be negative, because this type of antibody disappears quickly. Serological tests prove the presence of IgM and IgG antibodies in the blood, which are formed as an immune response of the body after contact with the SARS-CoV-2 virus.
According to current data, IgM antibodies in the blood can be detected as early as possible at the end of the first week after the onset of symptoms, whereas IgG antibodies most often appear shortly after the IgM antibody in the second week.
"Tests for IgA and IgM antitela have not been particularly productive in this pandemic," says Lorenz.
Negative antibody test
A negative test does not always mean that you are not protected from viruses. And those who test negative may have a certain level of protection thanks to T-lymphocytes, another method of the body's fight against the virus.
T-lymphocytes do not "jump “on viruses before they” attach" to our cells, but do it later, that is, they attack the cells in which the virus settles. The role of T-lymphocytes is very important for our immune system.
Many who have had a relatively mild coronavirus infection lose antibodies quickly, but that doesn't mean that T-cell levels decline as quickly, epidemiologists say, noting that some laboratories can also test for T-cell levels.
Does a positive antibody test mean more freedom of movement?
Many countries grant the same rights to fully vaccinated people and those who have crossed the covid in the past six months. But the final proof is a PCR test, not an antibody test.
Purpose of the antibody test
"For people with compromised immune systems or patients taking immunosuppressive drugs, the antibody test has a purpose," says Wakl, adding that those who receive the second dose of the vaccine can check the level of the antibody in the body, while for everyone else, vaccinated and those who have suffered covid, the test value is limited.
Lorenz says that anyone who wants to assess the level of immune protection against the coronavirus should choose a neutralization test. He also added that he can't think of any case where it would be wise to do a simple antibody test, except when you want to know if you have the virus or not.This text 03 HAZIRAN 2021 It was written on.
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