Why does obesity increase the risk of severe Covid infection?

The link between obesity and severe Covid-19 infection may be explained by an underactive immune response, according to a study by scientists at the Cambridge Institute of Therapeutic Immunology and Infectious Disease (CITIID) and Wellcome Sanger Institute. The researchers demonstrated that immune cells show a blunted inflammatory response in patients who are obese. 

Nearly 6.9 million people have died from Covid-19, and obesity is one of the major risk factors for severe infection. However, the underlying cause of the link between obesity and severe Covid has not been clear. 

“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.

The researchers analyzed blood and lung samples from 13 obese patients with severe cases of Covid that required mechanical ventilation. While studying the activity of cells in the samples, the experts discovered that the obese patients had underactive immune and inflammatory responses in their lungs.  

“This was really surprising and unexpected,” said Professor 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.”

According to the researchers, the findings could have important implications both for the treatment of COVID-19 and in the design 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.”

The study is published in the American Journal of Respiratory and Critical Care Medicine.

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By Chrissy Sexton, Earth.com Editor

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