In a new study, researchers reported series of biomarkers, or biological signals, associated with white blood cell activation and obesity that can help predict severe Covid-19 outcomes for patients.

For the study, published in the journal Blood Advances, the Yale researchers used proteomic profiling – a screen for multiple proteins within the blood. This was carried out to analyse samples taken from 100 patients with different levels of Covid-19 severity.

The researchers also examined clinical data for over 3,000 additional patients with Covid-19 within the Yale New Haven Hospital system.

Lead author Dr. Hyung Chun, director of translational research at the Yale Pulmonary Vascular Disease Program said: “Patients with high levels of these markers were much more like to require care in the intensive care unit, require ventilation, or die due to their Covid-19.”


They found that five proteins (resistin, lipocalin-2, HGF, IL-8, and G-CSF) that are associated with neutrophils, a type of white blood cell, were elevated in the Covid-19 patients who later became critically ill. Many of these proteins had previously been associated with obesity but not with Covid-19 or other viral illnesses.

The researchers further observed that elevated neutrophil biomarkers for severe Covid-19 patients were evident before those symptoms appeared.

All Covid-19 patients who were admitted or transferred to the ICU had elevated neutrophil activation markers, while these biomarkers remained low for patients who never developed a severe illness. None of the patients with lower neutrophil biomarker levels died.

The study also underscores the connection between Covid-19 and obesity, researchers noted in their study.

According to the researchers, neutrophils are inflammatory cells. So, it makes sense that they would be elevated in the context of both obesity and Covid-19. Both cause inflammation that leads to tissue damage and organ failure.