Coronaviruses are not unknown pathogens. So far, they have mostly come from the form of harmless cold viruses. Anyone who was infected with them probably has a better defense against SARS-CoV-2.

Four types of coronavirus were already present before the Covid-19Pathogen spread among people. They lead to cold symptoms, which are usually harmless. Now researchers from Berlin Charity found that certain immune cells that people who were infected with these cold coronaviruses had made raised the immune response against SARS-CoV-2 strengthen.

T helper cells also recognize SARS-CoV-2

For the study, which was published in the journal “Science”, from mid-2020 almost 800 people who had not yet come into contact with SARS-CoV-2 were recruited. Checks were carried out at regular intervals to see whether they were familiar with the new one Coronavirus had infected. 17 people were identified. you immune system was before and during the infection analyzed. The realization: Your body mobilized the so-called T helper cells, which he had formed against the known cold coronaviruses, also against SARS-CoV-2.

T helper cells are responsible for the control and coordination of the immune response. They ensure that other immune cells fight pathogens that penetrate the body directly and form tailor-made antibodies. So-called T helper memory cells survive in the body for many years and ensure a quick immune response when they come into contact with the pathogen again.

“Universal Coronavirus Memory”

The mobilization of these cells led to an improved immune response to SARS-CoV-2. For example, they recognized a certain area of ​​the characteristic spike protein in the novel coronavirus, that of the known Cold viruses is similar and so fought the pathogen. Experts speak of cross-reactivity.

“In colds with more harmless coronaviruses, the immune system builds up a kind of universal, protective coronavirus memory,” explains Dr. Claudia Giesecke-Thiel, lead author of the study. “If it comes into contact with SARS-CoV-2, such memory cells are activated again and now also attack the new pathogen. This could contribute to a faster immune response against SARS-CoV-2, which would allow the unhindered spread of the Virus in the body at the beginning of the infection and thus presumably influences the course of the disease positively. “

But the scientist also emphasizes: “That does not mean that you are definitely protected from SARS-CoV-2 if you have had colds in the past vaccination is important in any case. “

Vaccination ensures a quick immune response

Because: The immune-boosting effect of the cross-reacting T cells the scientists also pointed out with a vaccination with the vaccine of Biontech after. An analysis of the immune response of 31 healthy people before and after vaccination showed: While normal T helper cells activated gradually over a period of two weeks, the cross-reactants spoke T helper cells respond to the vaccination very quickly within a week. The body was able to produce antibodies very quickly and slow down the spread of infection at an early stage.

“Even with the vaccination, the body can at least partially fall back on an immune memory if it has already suffered colds with endemic coronaviruses,” says Prof. Dr. Andreas Thiel, also lead author of the study. “That could explain the surprisingly quick and very high protective effect that we observe, at least in younger people, after a Covid 19 primary vaccination.”

Cross immunity decreases with age

The researchers also determined another fact: Cross-immunity decreases with age. Both the number of cross-reacting T cells as well as their bond strength (i.e. how well they catch the pathogen) was lower in older study participants than in younger ones. This is attributed to natural changes in an aging immune system.

“The advantage that a harmless coronavirus cold often brings younger people in fighting SARS-CoV-2 and also in building up vaccination protection is unfortunately less in older people,” says Prof. Thiel. This could explain why older people are more likely to get seriously ill with Covid-19 and why their vaccination protection is often weaker than that of younger people. “A third booster vaccination could presumably compensate for the weaker immune response in this more vulnerable population group and ensure adequate vaccination protection,” Thiels concluded.

Important NOTE: The information is in no way a substitute for professional advice or treatment by trained and recognized doctors. The contents of t-online cannot and must not be used to independently make diagnoses or start treatments.


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