Some patients suffering from severe conditions may not develop immunity to COVID-19
High levels of a molecule seen in severe COVID-19 patients may prevent them from developing long-term immunity to the novel coronavirus, according to a study which says such individuals tended to make very few of a type of cells which produced antibodies against the virus.
Scientists, including those from Harvard University in the US, noted that the release of massive amounts of molecules involved in cell-cell signalling in the body called cytokines can lead to some of the most severe symptoms of COVID-19.
They said high levels of cytokines increased inflammation, and created a feedback loop in which immune cells produced more of these molecules in a process called a cytokine storm.
According to the study, published in the journal Cell, cytokine storms may prevent COVID-19 patients from developing long-term immunity since such individuals make very few of the type of B cells which produce antibodies.
"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," said study co-senior author Shiv Pillai from Harvard University.
In the study, the researchers assessed germinal centres, which are areas within the lymph nodes and spleens where B cells mature and start producing antibodies.
According to the scientists, in people with severe COVID-19, one of most abundant cytokines released is called TNF.
In infected mice, they said TNF appeared to block the formation of germinal centers, Economic Times reported.
Without the germinal centers, the scientists said the immune system may not develop long-term memory to the virus.