Why does the immune antibody to Covid-19 in some people disappear after only a short time?

Articles Jul 13, 2020 20:58

Is it true that those who have contracted Covid-19 and are immune to this virus? If so, how long? An antibody study by the Helmholtz Institute will shed some light on this.

After being infected - Corona will be immune - which is the hope of many people when the beginning of the pandemic - Covid-19. Even the whole concept of herd immunity is based on this notion. However, many studies show that antibodies exist only limited in the blood. What this means?

During the corona pandemic many hope for immunity - after undergoing infection or through an upcoming vaccination. Both of these can help the immune system fight off pathogenic viruses and protect people from the risk of Covid-19 disease.

But many studies show that, in people with few or no symptoms at all, just a short time after being infected, the antibodies in the blood can no longer be found. It is not clear what this means for immunity.

Why does the immune antibody to Covid-19 in some people disappear after only a short time?

However, the observations give rise to suspicion of antibody tests and the current controversy over immunological certifications. Even the development of vaccines needs to understand the immunity to Sars-CoV-2.

Immune reactions do not seem to be consistent in everyone. Basically the immune system reacts to the so-called T-cells in disease-causing organisms. Some -T cells activate B-cells, then produce antibodies. Antibodies bind to certain traits of an infected animal and can inactivate them.

In mild cases, it is difficult to detect Covid 19 antibodies quickly

At first glance, the presence of special antibodies is a good sign of the previous infection. However, a study by Zürich University hospital in people with mild or asymptomatic disease progression did not show the so-called IgG-antibody in the blood.

This is important for immune memory - whereby the immune system is exposed to the pathogen again and more quickly. The study so far is only a preprint - that is, it has not been tested or published by a specialist in a thematic journal.

Why does the immune antibody to Covid-19 in some people disappear after only a short time?

Another study published by the Lübeck health agency is also considered a preprint according to which 30% of the 110 people infected with Corona also have moderate symptoms of Covid-19 and no antibodies. In the journal Nature Medicine, Chinese researchers said that those infected without symptoms, the antibody concentration in the blood after only a short time has decreased significantly.

These studies make the persuasion of antibody mass tests, to elucidate the coronary-wave of infection among the public, suspicious. Moreover, the immunity generated by antibodies in many people infected with Sars-CoV-2 after a short time is no longer available.

Covid 19 suspicious immune certificate 

From what should be on Thomas Jacobs of the Bernhard-Nocht Institute in Hamburg on tropical medicine (BNITM) is skeptical about granting immune certificates to people who have been infected with Sars-CoV-2. There is nothing scientifically proven that the presence of antibodies in itself can protect against a new infection.

We do not yet know exactly how antibodies will protect - this immunologist says. Studies show that such protection may be available, but the level of the antibody must be effective in order to work, which is unknown. "

Why does the immune antibody to Covid-19 in some people disappear after only a short time?

Klaus Cichutek, president of the Paul-Ehrlich Institute (PEI), emphasized that it is necessary to distinguish antibodies: "The types of antibodies differ in quality and not all can hinder infection." It is important to find hard data: Whether or not to form an immunity, this must be measured in practice.

The results are not surprising for Jacobs, who found that in patients with no symptoms or without antibodies or antibodies that disappear very quickly: "a small number of viruses in the neck or throat may not enough to trigger a large antibody response or to produce immune-T-cells ".

The truth about the Covid-19 immune system

This adaptive immune system makes sense, because in everyday life we ​​are often exposed to germs. If we can respond with light weapons, then there's no need to bring cannons to fight.

In the case of severe illness due to Covid-19, it is likely that the disease here has formed a long-term protection and protection mechanism.

Why does the immune antibody to Covid-19 in some people disappear after only a short time?

Studies on other types of viruscorona show that, if a recurrence of a Sars-CoV-2 infection can generate immunity in the long run, such as Shane Crotty, a virologist at La Jolla Institute for Immunology in Kalifornia explained in the journal Nature. A symptom of reduced immunity may therefore take longer.

It is not clear which part of the immune system is particularly important for this protection. 

"In addition to antibodies that produce B-cells, the response of the –T cell to the pathogen is equally important," Jacobs explained. Which mechanism here works especially, this is a very significant question for vaccine development.

There may be partial immunity of Covid 19

In this regard, the infection researcher has taken note of studies conducted in the United States and Germany: up to 30% of people who are not infected with Sars-CoV-2, but some certain T-helper cells, which respond to this virus: "They may have been exposed to the so-called Common-Cold-Coronaviren" - that is, to other types of virus which causes the common cold.

Such exposure may produce a partial immunization against Covid-19. This explains why, when infected, there are differences in motivation and symptoms, Jacobs conjectures. It remains unclear how this protection and reactivation of this T-cell functions.

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