Researchers have discovered that a simple blood test can help predict which COVID-19 patients are more likely to die from the disease.

As reported in the journal Science Advances, the team at the University of Montreal looked for biomarkers in the blood of 279 patients during their hospitalization for COVID-19. Their disease severity ranged from moderate to critical, and the team looked for everything that could potentially stand out.

Blood was collected 11 days after the onset of symptoms, and patients were monitored for at least 60 days after that. The team found that people with a high amount of viral RNA – the genetic material of the virus – in their blood were more likely to die.

“In our study, we were able to determine which biomarkers are predictors of mortality in the 60 days following the onset of symptoms,” Dr Daniel Kaufmann, co-lead author with colleagues Nicolas Chomont and Andrés Finzi, said in a statement. “Thanks to our data, we have successfully developed and validated a statistical model based on one blood biomarker.”

The team looked at other possible biomarkers, but they did not have the same results found by measuring the viral RNA. Adding biomarkers to the model didn’t improve the predictive ability either.

“Among all of the biomarkers we evaluated, we showed that the amount of viral RNA in the blood was directly associated with mortality and provided the best predictive response, once our model was adjusted for the age and sex of the patient,” added Elsa Brunet-Ratnasingham, a doctoral student in Kaufmann’s lab and co-first author of the study.

The team conducted tests through the three main waves of the pandemic and found the model reliable. They hope that this approach is employed to quickly recognize who’s most at risk and offer them new treatment.