Nearly half a year into the coronavirus pandemic, hospital clinicians still have no good way of knowing how and why some of their COVID-19 patients recover from infection, whereas others take a turn for the worse and die. A recent study of 22 hospitalized COVID-19 patients provides some clues. Through an extensive computational analysis of the patients’ antibody features and functions, researchers report marked differences between those who survived and those who died. Notably, antibody responses against SARS-CoV-2’s spike protein were stronger among COVID-19 survivors, whereas antibody responses targeting the virus’s nucleocapsid protein were elevated in patients who died. The findings were published last month (July 30) in Immunity.

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While it’s not clear if these different antibody responses are the reason for the patients’ different disease trajectories, the research “provides mechanistic insights into the nature of the immune response to SARS-CoV-2,” notes Stanford University immunologist Bali Pulendran, who wasn’t involved in the study. In addition, “you could [potentially] have a means of monitoring these COVID patients to identify these signatures, and thereby get a sense of what the prognosis could be.”

In late February, as COVID-19 tore through nursing homes in Seattle, some patients were seen by University of Washington physician and immunologist Helen Chu at Harborview Medical Center. Chu puzzled why certain COVID-19 patients, who seemed fine at first, would rapidly deteriorate from one day to the next and die, recalls her collaborator Galit Alter of the Ragon Institute of Massachusetts General Hospital, MIT, and Harvard.