Massachusetts General Hospital researchers have identified what’s known as a protein “signature” linked to severe health outcomes including death for people who contract COVID-19, according to an article published Tuesday in the Harvard Gazette.

They defined patients with severe COVID-19 as those who either required intubation or died within 28 days of admission to MGH, the Gazette article said.

Researchers analyzed blood samples from 306 patients who tested positive for COVID-19, as well as samples from 78 patients with similar symptoms who tested negative, the article said.

The team determined that “the most prevalent severity-associated protein, a pro-inflammatory protein called interleukin-6, or IL-6, rose steadily in patients who died, while it rose and then dropped in those with severe disease who survived,” the Gazette article said.

The article said early attempts by other groups to treat COVID-19 patients suffering from acute respiratory distress with IL-6 blockers “were disappointing,” though more recent studies combining these meds with a steroid called dexamethasone could be promising.

“They are highly likely to be useful in figuring out some of the underlying mechanisms that lead to severe disease and death in COVID-19,” Goldberg, director of the Goldberg Laboratory at MGH and a professor of emergency medicine at Harvard, told the Gazette.

Back in February, researchers at the Ragon Institute of MGH, MIT and Harvard and Massachusetts General Hospital published a study in the journal Nature Medicine that found one type of antibody may be driving severe COVID-19 in adults, while a different type may be driving a rare but dangerous condition called multisystem inflammatory syndrome in children (MIS-C) that children with COVID-19 can develop.

In the case of adults with severe COVID-19, researchers said, increased levels of different antibodies, IgA antibodies, could be the problem.

Yannic Bartsch, the study’s first author and a research fellow at the institute, said in a February statement, “In adults with severe COVID-19, high levels of IgA antibodies could be driving neutrophils to release too many cytokines, with the potential of causing a cytokine storm.”.