It seems that the problems of severe COVID-19 patients might not end anytime soon. Health experts claim that severe COVID-19 patients may never develop immunity against the coronavirus due to a unique molecule present in their bloodstream. Such individuals make very few cells that are responsible for producing antibodies. Several scientists including those from Harvard University have claimed that the release of a large amount of cell to cell signaling molecules called cytokines leads to severe symptoms in COVID-19 patients. This phenomenon is also known as the cytokine storm.
The huge release of cytokine molecules leads to inflammation in the body which further results in the release of more cytokines. This entire cycle is known as the cytokine storm. The cytokine storm results in lesser production of type B cells that are responsible for producing antibodies against the virus. Hence, severe COVID-19 patients may never develop long-term immunity against the virus. A senior co-author of the study from Harvard University, Dr. Shiv Pillai, says, “We’ve seen a lot of studies suggesting that immunity to COVID-19 is not durable because the antibodies decline over time. This study provides a mechanism that explains this lower-quality immune response.”
There are certain specific areas in the lymph nodes and spleen that are responsible for the maturation of B-cells and T-cells. These areas are known as germinal centers. For the purpose of this study, the scientists examined the germinal centers of the lymph nodes and spleen of severe COVID-19 patients. Another co-author of the study from Harvard University, Dr. Robert Padera, says, “When we looked at the lymph nodes and spleens of patients who died from COVID-19, including some who died very soon after getting the disease, we saw that these germinal center structures had not formed.”
Scientists claim that TNF is one of the most abundantly released cytokines in severe COVID-19 patients. In studies involving mice, TNF leads to blocking of germinal center formation. However, mice who had their TNF gene blocked or deleted showed the production of germinal centers. This phenomenon is also seen in certain patients of Ebola. When scientists further studied patients with active infections of COVID-19, they found that in these patients, even though germinal centers were not formed, B-cells were still active. This allowed them to produce some antibodies to neutralize the coronavirus.
Without the formation of any germinal centers, the bodies of severe COVID-19 patients may not remember the coronavirus for a long time. However, scientists hope that a coronavirus vaccine will be able to overcome the cytokine storm and help patients recover.