Researchers have learned a lot about COVID-19 since the start of the pandemic, but there’s still a lot we don’t know. One of the things that makes this virus and the disease it causes so threatening is that in some cases, the immune system becomes overreactive in response to this infection.
This abnormal immune response has been linked to a more serious infection that can lead to long-term consequences and even be fatal.
Most of the time, the immune system works like a finely tuned machine, repairing, healing and restoring the body. The process by which this happens is complicated, but it involves a balance of pro-inflammatory and anti-inflammatory reactions.
Researchers don’t know why, but in people with severe COVID-19, these responses are imbalanced, resulting in excessive viral replication and inflammation.
COVID interferon reactions
Interferons are signaling proteins made by infected cells that warn other cells to increase their antiviral efforts. studies show that COVID changes the immune system’s response by affecting interferons. This effect seems particularly harmful when it comes to: type l interferon† The Sars-Cov-2 virus seems to suppress type I, causing more inflammation.
Research shows that patients with a robust type I interferon response at the start of a COVID-19 infection clear the virus more effectively and quickly. A muted response often leads to severe, ongoing illness.
Sars-Cov-2 and cytokines
Another way COVID changes the normal immune response is through the release from cytokinesproteins that allow cells in the body to communicate.
When a Sars-Cov-2 infection affects the type I interferon and causes increased inflammation, the body releases a large number of pro-inflammatory cytokines, which cause widespread damage.
Researchers don’t fully understand the mechanisms that COVID uses to trigger a cytokine storm, but studies show a direct relationship between the number of pro-inflammatory cytokines in the blood and the severity of the infection. Experts believe the virus uses an enzyme called ACE2 to enter the lungs, where it quickly replicates while releasing cytokines, leading to systemic inflammation and organ dysfunction.
Multisystem Inflammatory Syndrome in Children
Multisystem inflammatory syndrome in children (MIS-C) is another example of what happens when COVID overtakes the immune system. While most children experience mild infections, those who develop MIS-C have severe inflammation in the organs and tissues, including the digestive system, skin, eyes, blood vessels, and brain.
Much is unknown about MIS-C, although researchers believe it results from an excessive immune response to COVID-19. Although it is rare, children with this syndrome can rapidly deteriorate, putting their lives at risk.
Time is of the essence when the immune system responds to the Sars-Cov-2 virus or another invader, but it must also attack the right target. In some cases, COVID-19 causes the body attack yourself†
While the inflammatory response is likely partly responsible for this response, studies also show that the body sometimes produces autoantibodies that attack white blood cells, including B and T cells, which the body needs to kill the virus. Research also shows that these antibodies are not present at the beginning of the infection, indicating that the virus acts directly on the immune system to make them.
This system includes the physical barriers that prevent infection, such as the skin and mucous membranes, and mobilizes the acquired immune system, which has a much more specific response. The innate immune system is inherited, meaning some people have one that immediately recognizes and responds to the virus and others don’t.
Researchers have also found bacterial debris in the blood of people with severe COVID-19. This debris is made up of things like bacterial DNA and cell walls, and the more there is in the blood, the more serious the infection.
Researchers believe that bacterial waste comes from beneficial bacteria in the lungs, throat and intestines, implying that it enters the bloodstream in severe infections and possibly increasing inflammation.
This study showed that COVID-19 survivors have a long-term reduction in dendritic cells, which can increase the risk of secondary infections and long-term treatment of symptoms.
Long term effects
COVID can have others long-term Effects on immunity. Some researchers believe that persistent fatigue, pain and neurological symptoms after infection may be due to bits of the virus hiding in the organs. These viral bits can also trigger an excessive immune response and prolonged inflammation, although the person may no longer be able to infect other people.