Researchers from the NMCB have published an article in the international scientific journal Journal of Clinical Immunology about their research project Immunostratify on post-COVID. In the article, they describe new findings on how the immune system in post-COVID patients responds to viral stimuli.
In this study, the researchers examined how the immune system of people with post-COVID responds to viral stimuli. They aimed to determine whether the immune cells in these patients react differently from those of people without post-COVID.
Why this research?
People with post-COVID often experience prolonged symptoms. Common complaints include severe fatigue, difficulty with exertion, and concentration problems. However, it is still not fully understood what exactly goes wrong in the body.
The NMCB is investigating whether the immune system plays a significant role in this. Previous research has shown that an infection can permanently alter the immune system. Some immune cells seem to remain “on” even after the infection has passed. This can cause them to react too strongly to new stimuli.
The researchers wanted to know if this also happens in post-COVID patients.
What did the researchers do?
For the study, the researchers used blood samples from two groups of people with post-COVID:
- One group of people who had been hospitalized with COVID-19 a few months earlier;
- One group of people who had been experiencing post-COVID symptoms for several years after a relatively mild infection.
These groups were compared with individuals who had had COVID but had fully recovered.
In the laboratory, the immune cells were exposed to simulated viral particles. This allowed the researchers to measure how strongly the cells responded to a viral stimulus.
What did they find?
The researchers found that the immune cells of people with post-COVID reacted much more strongly to viral stimuli than those of healthy controls. The cells produced more of certain substances, called type I interferons. These substances are important for defense against viruses.
Without viral stimuli, there were no significant differences between the groups. The overreaction only occurred when the immune cells were reactivated.
Moreover, in some patients, the stronger the immune response, the more severe the fatigue. While this connection was not as clear in all groups, it was still notable.
What does this mean?
The results suggest that the immune system in post-COVID patients may have become hypersensitive. The immune cells appear to remain “on alert” and overreact to new stimuli.
This may help explain why some people continue to experience symptoms long after having COVID. While this doesn’t mean a treatment is available yet, it provides important clues about what is happening biologically in the body.
Link to the publication
https://link.springer.com/article/10.1007/s10875-025-01969-w
For who wants to know more: Marjan Versnel answers questions on the project and immunesignatures in these video’s