Obesity has been linked to a myriad of health issues, Another one to join the is vulnerability to COVID-19, as a new study has found a causal link between the two.

The study, published in American Journal of Respiratory and Critical Care Medicine, was led by scientists at the Cambridge Institute of Therapeutic Immunology and Infectious Disease and Wellcome Sanger Institute, England.

In the study, researchers found that immune cells in obese people showed a muted inflammatory response. This underactive immune response is being attributed to an increased risk of severe COVID infection.

“Obesity affects 40% of U.S. adults, is associated with a proinflammatory state, and presents a significant risk factor for the development of severe coronavirus disease (COVID-19). To date, there is limited information on how obesity might affect immune cell responses in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection,” the authors wrote in the paper.

According to Earth.com, around 6.9 million people have died from COVID-19, and obesity has been considered a major risk factor for severe infection.

“During the pandemic, the majority of younger patients I saw on the COVID wards were obese. Given what we know about obesity, if you’d asked me why this was the case, I would have said that it was most likely due to excessive inflammation. What we found was the absolute opposite,” explained professor Menna Clatworthy, as per the outlet.

For the study, blood and lung samples of 13 obese patients with severe cases of COVID that required mechanical ventilation were collected. On analysis of the activity of cells in the samples, it was found the obese patients had repressed immune and inflammatory responses in their lungs.

“This was really surprising and unexpected,” said Clatworthy. “Across every cell type we looked at, we found that the genes responsible for the classical antiviral response were less active. They were completely muted.”

The findings of the study could lead to improved treatment of COVID-19 as well as better designing of clinical trials to test new treatments.

“What we’ve shown is that not all patients are the same, so we might need to tailor treatments,” said study co-author Dr. Conway Morris. “Obese subjects might need less anti-inflammatory treatments and potentially more help for their immune system.”

In another recent study, childhood obesity has been found to be associated with an increased risk of four of the five newly proposed subtypes of adult-onset diabetes. “Childhood obesity appears to be a risk factor for essentially all types of diabetes in adults, except for mild age-related diabetes. This stresses the importance of preventing obesity in children," the authors said.