A large team of researchers with members affiliated with a host of institutions in France has identified what they believe is a hallmark of severe COVID-19 patients. In their paper published in the journal Science, the group describes their study of 50 COVID-19 patients in France and what they learned from them.

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The global pandemic has led medical scientists around the world to study the SARS-CoV-2 virus and associated infections. One characteristic of such infections is the difference in degree of symptoms: some people are asymptomatic, while others find themselves unable to breathe. Researchers are hoping that if the reason for different reactions to infection can be found, a means of treating people with severe infections may soon follow. In this new effort, the researchers studied 50 patients in French hospitals with varying symptoms—from those with a minor cough to those on ventilators. Their goal was to find a common factor in the patients with severe symptoms.

In analyzing blood, tissue, immune cells and other samples from the patients, the researchers came upon what they believe is a signature for people with severe infections—a combination of an interferon response deficiency and exacerbated inflammation. They suggest the signature may represent a hallmark for severely ill COVID-19 patients. The researchers suggest their findings could lead to therapies that boost interferon response to an infection while also reducing inflammation.