MORGANTOWN, W.Va. (WBOY) — A study from the West Virginia University School of Medicine aimed to deepen the medical community’s understanding of why obesity increases people’s risk of being hospitalized, placed on a ventilator or dying due to COVID-19.

It was conducted by WVU School of Medicine researcher Katherine Lee and published in iScience.

During the study, researchers exposed two groups of mice to the original, alpha strain of SARS-CoV-2, the virus that causes COVID-19. One of the groups of mice was on a normal diet and at a healthy weight, and the other group was fed a diet designed to induce obesity.

The study found that obese female mice that were exposed to the virus had a 100-fold increase in viral RNA than the control female mice and that there was no difference in the viral RNA burden between the male mice.

Additionally, the study found that the obese mice experienced different T cell activations than their regular-weight counterparts; specifically, T cells that encode for inflammation were higher in obese mice, whereas T cells that encode for T cell proliferation, were low in the obese mice and high in the regular-weight mice.

Both inflammation and T cell proliferation are part of the body’s immune response, but inflammation is considered damaging when it lasts too long and T cells attack foreign substances in the body.

The study also found that obesity did appear to hinder B cell responses in the lungs of male mice, but that it did not appear to worsen morbidity.

Our data suggest that female K18-hACE2-mice on normal diets have lower viral RNA burden and decreased inflammatory responses, and [obesity] impairs the clearance of virus in the lung which results in their enhanced morbidity. [Obesity] appeared to affect female mice more than male mice following SARS-CoV-2 challenge; however, differences were appreciable in males as well. Collectively, these data begin to shed light on the effects of DIO on COVID-19.

Obesity and metabolic dysfunction drive sex-associated differential disease profiles in hACE2-mice challenged with SARS-CoV-2

The differences led to the obese mice showing symptoms sooner and experiencing disease at a higher rate.

After seven days, the obese female mice had a zero percent survival rate and the female control mice had a 20% survival rate. It found no statistical differences in survival between the groups of male mice.

The study acknowledged the limitations the mice model has in evaluating human disease comorbidities.

“Clinically, a lot of data shows that men are more predisposed to severe COVID-19 than women,” Lee said to WVU Today. “While we can’t translate our findings from female mice directly to female humans, they do indicate an area for future study. Why does sex play a role in outcomes of COVID-19? And how is obesity a confounding factor?”

WVU said the findings are relevant to the development of new vaccines and treatments for COVID-19, as well as other respiratory diseases.

The study disclosed that the project was supported by the Vaccine Development Center at the West Virginia University Health Sciences Center.