The release of massive amounts of proteins called cytokines can lead to some of the most severe symptoms of COVID-19. When large numbers of immune cells release cytokines, this increases inflammation and creates a feedback loop in which more immune cells are activated and this is sometimes called a cytokine storm.

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An August 19 study in the journal Cell now suggests that high levels of some cytokines may also prevent people who are infected from developing long-term immunity as affected patients were observed to make very few of the type of B cells needed to develop a durable immune response.

"We've seen a lot of studies suggesting that immunity to COVID-19 is not durable because the antibodies decline over time," says co-senior author Shiv Pillai, a professor at Harvard Medical School and member of the Ragon Institute of Massachusetts General Hospital, MIT, and Harvard. "This study provides a mechanism that explains this lower-quality immune response."