A German-Austrian research team reportedly discovered the reason for the so-called post-COVID-19 syndrome, also known as Long COVID.

The researchers found that the body's defensive system seems to be out of balance for a longer amount of time following a coronavirus infection. The study was published on Monday in the journal Frontiers in Medicine.

The specialists routinely checked the subtype distribution of immune cells, their condition, and other variables in the lab. The test subjects' blood was examined for immunological messenger substance (cytokine) concentrations.

Scientists argue that a certain trait is shown by the study. The number of CD4- and CD8-positive T cells that specifically reacted to SARS-CoV-2 and released interferon-gamma and tumor necrosis factor was higher in patients with post-COVID-19 syndrome.

Increased blood levels of tumor necrosis factor are seen as a sign of inflammatory processes. The cells were also marked by the so-called CD40 ligand surface molecule at the same time. CD40 ensures that B cells produce antibodies at an increasing rate.

Together with T cells, B cells are white blood cells that are a part of the immune system's adaptive component, or the part that can adjust to new infections.

The research, according to the authors, documented alterations in immunologic status among those who recovered from COVID-19, whether or not they also experienced longer-term health issues.

"This may have potential for future epidemiologic research and targeted therapies," the study stated.

It is worth noting that post-COVID-19 syndrome is the term used to describe symptoms that persist for more than 12 weeks following a severe infection with the SARS-Cov-2 virus.

According to estimations from the World Health Organization (WHO), 10 to 20% of those affected by COVID-19 experience longer effects.

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