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Many are concerned that after vaccination, the body’s defenses are not adequately prepared to protect against COVID-19. They hope that laboratory tests for the presence of antibodies will show it. However, only a few tests can answer this question.
- For months, scientists have been looking for a marker in the blood of healed and vaccinated people that will be a reliable indicator of the level of immunity against the coronavirus
- However, until researchers find such a “protection correlation”, they will use the research of antibodies against SARS-CoV-2
- Prof. Harald Renz from the University Hospital of Gießen-Marburg recommends that patients at risk have an antibody test two to three weeks after taking the second dose
- Experts do not recommend universal vaccination of humans with a third dose because vaccine studies have clearly proven one thing: in the vast majority of healthy people, vaccines work well and protect against the severe course of COVID-19
- More information can be found on the Onet homepage
Author: Pia Heinemann / The World
They survived the year and a half of the pandemic, wore face masks, kept their distance from others, and finally got vaccinated. They did everything in their power to avoid contamination with a pathogen that scientists and doctors still do not know enough about to conclude what harm it can do to the body in the long term. The question they are asking themselves today is, “Did my vaccination work?”
This is a question that health officials are also asking in the face of the global vaccine shortage. Who really needs the third dose because the first two didn’t protect him well enough?
In search of an answer scientists are trying to develop a simple and quick COVID-19 protection test. In the blood of vaccinated and convicted people, they look for a marker that shows whether a person is immune to the virus. They want to find a molecule or cell analogous to the “protection correlate” that will reliably indicate that the body’s defenses have been activated well enough that it can cope with SARS-CoV-2, and do so throughout its life.
Medicine knows such a correlate of protection against infectious diseases, e.g. rabies, rubella or hepatitis. For example, before conception, doctors recommend that women who are planning to become pregnant should have a blood test for rubella to check the concentration of antibodies against this disease. This is important as the rubella virus can lead to deafness and other serious problems in the unborn baby. If the antibody titer exceeds a certain value, then everything is fine. However, if the levels are too low, malformations could develop in the unborn child if the mother becomes infected with the rubella virus during pregnancy. To exclude such a scenario, a woman may undergo a booster vaccination.
Because The body’s defenses work basically the same way for all pathogens, so in theory it should be possible to find a good marker of immune protection also after vaccination against COVID-19. “The first time you come into contact with a virus or vaccine antigen, nonspecific defense is activated: different antibodies are released, but they do not exactly match the pathogen,” explains immunologist Christine Falk of Hannover Medical School.
However, these antibodies are not suitable as markers, so it is necessary to search for the biomolecule in specific antibodies. Pathogens that have escaped from the first line of defense are intercepted and combated by specific defense, which reacts somewhat slower. Different classes of special antibodies (such as so-called immunoglobulins M and G, IgM, IgG) stick together and neutralize viruses.
In addition, memory cells (B cells) are trained, which, in the event of re-infection, quickly release additional specialized antibodies. T lymphocytes also take part in the fight against the pathogen. When this specific defense is sufficient, whether as a result of infection or vaccination, we are protected against the severe course of the disease.
But in some people this “training” is not smooth: they only produce a few specific antibodies, the memory of B cells is not activated, special messenger substances are not activated or hardly any T cells are formed. “It happens more often among the elderly and those whose immune systems are weakened by chronic diseases such as diabetes, rheumatism and obesity,” says Falk. Unfortunately, they are the ones who are particularly at risk from the severe course of COVID-19.
- Read also: The course of COVID-19 and symptoms. How to distinguish a mild form of the disease from moderate and severe?
Further part below the video.
The T cell test may not give a definite answer
On the one hand, it is difficult to define the right marker. On the other hand, there is another obstacle: levels of specific antibodies decline over time. In addition, B and T lymphocytes are located in lymphoid tissue and bone marrow. They only migrate into the blood when alerted to the body’s nonspecific defenses. If there is no coronavirus, they can only be found occasionally. The blood test will not yield any relevant information.
So is it worth looking for B or T lymphocytes in lymphoid tissue and bone marrow? Prof. Harald Renz, director of the Institute of Laboratory Medicine, Pathobiochemistry and Molecular Diagnostics, Gießen-Marburg University Hospital, would like to be able to check with a simple test how strong the immune system is.
«There are T cell tests on the market but they are not standardized, so measurements vary widely. Living cells need to be examined, and only a few laboratories can do this. Moreover, these laboratory tests are very complex. Personally, I would be skeptical if a doctor recommends that I take a T-cell test to test my immunity to the coronavirus»- he points out.
If we were to look for a way to determine the state of the immune system in this area, antibody testing seems to be more promising. Data from the vaccination analysis show that specific neutralizing antibodies can be found in all those who have developed good protection. These particles are also found in the blood samples of convalescents.
- Read also: Should I get the third dose if I have antibodies?
Do you want to test your COVID-19 immunity after vaccination? Have you been infected and want to check your antibody levels? See the COVID-19 immunity test package, which you will perform at Diagnostics network points.
When is the best time to test for COVID-19 antibodies?
“Antibody tests are only a support, a supplement to diagnostics” – emphasizes prof. Renz. «Until we know exactly what type of virus we are looking for, doctors and patients have to come to terms with it. However, if the immune system becomes very active after vaccination or illness, the protective effect is certainly better.
Because prof. Harald Renz recommends that at-risk patients have an antibody test two to three weeks after taking the second dose. «If the antibody titer is high, you can be pretty sure the protection is good. However, if it is low, you should think about a third dose ».
Antibodies to the protein of the spiny virus are very important. Anyone who decides to take the test should make sure that they are looking for IgG antibodies or many different classes of antibodies, as is the case with the so-called PAN antibody tests.
But do not rely solely on these antibody tests. If we do it too late, the antibodies may drop to a low level or disappear altogether. The test would then be negative, although in reality there would be enough B and T cells in the lymphoid tissue to prevent the disease.
However, experts do not make general recommendations that all vaccinated people should be tested for antibodies to SARS-CoV-2. Why? Because Vaccine research has clearly proven one thing: in the vast majority of healthy people, vaccines work well and protect against the severe course of COVID-19. Until a new virus variant emerges that can bypass vaccine protection, the vast majority of people who are vaccinated are adequately protected.
- Also check: A new variant of the coronavirus. XE is a hybrid that spreads faster than other mutations
Third dose for everyone?
Should fully vaccinated people receive a booster dose? Vaccine researcher Christine Dahlke of the University Hospital of Hamburg-Eppendorf said it would be good, especially for high-risk patients.
We have seen in vaccine studies for the MERS coronavirus, but also for other vaccines that a third activation of the immune system can significantly increase the B memory cell pool. These cells release antibodies that protect against infection by the virus. In a small study of the MERS vaccine, we found that it maintains high levels of antibodies for at least two years and does not drop after a few months
– added the expert.
Not only the better stimulation of the immune system speaks in favor of a booster vaccination for people at risk. “There are still too few vaccinations in Germany in relation to the high rate of development of the pandemic. Of course, this increases the risk of infection in patients with a low immune response ».
However, experts advise against widespread vaccination with the third dose. In the journal The Lancet, international researchers made it clear: in healthy people, vaccination provides good protection against infection and the severe course of COVID-19. In addition, there is still a shortage of vaccines worldwide, so it is the first two doses that need to be promoted first before the general public can receive a booster dose.
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