Scientists at the University of Washington School of Medicine in St. Louis in the United States have disproved the widespread belief that complications from SARS-CoV-2 are caused by overactive immune systems. The results, published in Science Advances, explain why anti-inflammatory drugs like dexamethasone do not help many patients with severe symptoms. At the same time, the destruction of the lungs in critically ill patients is still unexplained.
Researchers have found that an uncontrolled immune response is not a problem for the vast majority of those hospitalized with COVID-19. Only a few percent of patients had excess cytokine levels, which is defined as a cytokine storm. The proportion of patients with cytokine storms was found to be low even among those who were ventilated. In most cases, the inflammatory process did not reach the same level as in a comparable group of patients with influenza. Thus, respiratory failure does not occur due to over-activation of the immune system.
The researchers analyzed immune cells and molecules in blood samples from 168 patients with COVID-19, 26 patients with the flu, and 16 healthy people. The number of inflammatory cells in the blood of patients with COVID-19 and the flu was about the same. Seven COVID-19 patients (4 percent) showed signs of a cytokine storm with extremely high cytokine levels even when compared to other critically ill patients.
Usually, steroids are prescribed for seriously ill people, however, scientists emphasize, it does not seem that most of those who have serious symptoms really need them. In this case, the use of steroids can be harmful. Researchers are trying to identify the signs of an imminent cytokine storm so that anti-inflammatory drugs can be prescribed to those who really need it.
Most people who died from COVID-19 did not experience a cytokine storm. Therefore, the cause of most cases of respiratory failure in patients with COVID-19 remains unknown.
