“That’s actually exactly what we expect,” says Onur Boyman. “Because when the T cells are effectively activated, they migrate to the lymph nodes and therefore disappear from the blood.” T cells are specific, which means that a T cell only recognizes a fragment of a protein, for example a Fragment of the Sars-CoV-2 spike protein, which means that a confrontation with the virus would initially only cause these T cells to disappear from the blood. But this alone would not affect the defense against streptococci.
“However, there is also a so-called bystander activation through the inflammatory reaction,” explains Onur Boyman. “This stimulates a large proportion of the neighboring T cells to migrate to the lymph nodes.” Researchers also demonstrated this phenomenon with Sars-CoV-2. It was found that early and high bystander activity was present in people who were only mildly ill with corona. It was less in those who were severely affected. It is believed that the bystander activity is caused by the release of certain cytokines (such as interleukin-15) enhances the early immune response before specific T cells are present in sufficient numbers.
“On a scale where a rhinovirus does little to no damage to the immune system and HIV completely destroys it, I would place Sars-CoV-2 … somewhere in the middle.”Emanuel Wyler, Max Delbrück Center for Molecular Medicine
There are only few epidemiological indications of an immune deficiency caused by Sars-CoV-2. An analysis of the medical records of nearly two million Israelis found one significant increased number of diagnoses of tonsillitis caused by streptococcus. The risk increased by a third for those infected with corona compared to those who were not infected, but only from 0.62 to 0.96 percent. So it was still low. “For me, these data show: yes, there is an exhausting effect on the immune system, but it is probably not very large,” says Emanuel Wyler. “On a scale where a rhinovirus does little to no damage to the immune system and HIV destroys it completely, I would put Sars-CoV-2 — now that most people are vaccinated against the virus, recovered from it, or both — somewhere in the locate middle. Because there are still people who have to go to the hospital after an infection or die from it or are ill for weeks or months.«
In the acute phase, Sars-CoV-2 has many mechanisms to evade the immune system, for example by reducing the interferon secretion of infected cells and interfering with antigen presentation (the process by which the body knows if a cell is infected with a virus). Again and again persistent (permanent) Sars-CoV-2 infections are reported. In these people, the immune system is permanently affected by the virus. However, an immune deficiency that existed before the infection may also be the reason for a persistent illness. Other chronic infections are known to permanently activate mechanisms that turn off the immune system. so can In the long term, cytomegaloviruses disrupt the function of natural killer cells, which are used for the first virus defense. So far there is no evidence of this for Sars-CoV-2.
