It is a mystery that why novel coronavirus is fatal for some people but in most people, it causes only mild symptoms. In most of the cases, the worst damage is driven by the deranged response of the immune system to the COVID-19 caused by the novel coronavirus.
The blood sample analysis of many patients showed high levels of cytokines, the immune system protein. Researchers believe that cytokines release in the response of the immune system and that response is called a cytokine storm, in which body start attacking its own tissues and cells instead of just fighting against the virus.
Cytokine storm is known to occur in autoimmune disorders such as juvenile arthritis. These responses also happen in certain cancer treatment and get triggered by infections like flu. The study of patients who died with H1N1 influenza found that 81 per cent of the patients had symptoms of the cytokine storm.
Novel coronavirus has been circulating around for just a few months but research reveals that it can also cause such a catastrophic immune response and the intensity of storm triggered by this response is gale-force.
Several studies have been conducted to check if drugs that so up these cytokines or prevent their release in the first place, may prevent patients suffering from COVID-19 from dying. An immunologist and a virologist at the Georgia State University, Mukesh Kumar studies the response of the immune system to infections. In the experiments that were conducted in a high-security lab, h3e has been infecting animals and cells with the novel coronavirus, SARS-CoV-2 to learn the mechanism and see what happens.
He observed that novel coronavirus replicate very quickly after infecting the cell and there’s a lot of stress on that cell in a short time. The cell starts sending SOS signals. When a cell senses any foreign attacker, the body gives an immediate response to kill that foreign particle. It’s a self-protective mechanism so stops its spread to other body cells.
Certain cytokines trigger the death of cells. When many cells doing it in the same period, many tissues can die. In the case of COVID-19, the targeted tissue is in the lungs. As the tissue is damaged, the walls of tiny air sacs in the lungs become porous or leaky and get filled with fluid that ultimately causing pneumonia and depleting oxygen from the blood.
Kumar said that most of the cells die due to cytokine storm and they can’t recover. It plays the role in death in most of the cases. When lungs become damaged, respiratory distress syndrome occurs and other organs also start failing. The amount of cytokines released by the cells in response to the novel coronavirus is nearly 50 times more than as seen in the response to West Nile or Zika virus infections.
Scientists are not sure about the confirmed percentage of patients who will die because of a cytokine storm or why some infected people will go to have this reaction and on the other hand some won’t. People suffering from novel coronavirus die because of other confusing problems such as arrhythmias or cardiac arrest.
The haywire attack by the immune system does not play a role in the severity of the disease. The study conducted on 21 COVID-19 patients found that 11 patients who were severely ill as they needed more oxygen as compared to others who were just moderately ill to have more levels of cytokines. Another study based on 191 infected patients who were hospitalized in two different hospitals in China revealed that higher levels of IL-6 were linked to the higher risk of death from the novel coronavirus.