Researchers Unlock the Mystery of 'COVID Toe'

Some people infected with COVID-19 develop painful, itchy lesions on their feet and hands, which can last for months—and often they experience none of the more common symptoms associated with the disease, like cough, fever, or loss of taste and smell. The European Journal of Pediatric Dermatology described "an 'epidemic' of acute and self-healing vasculitic lesions of the hands and feet in asymptomatic children and adolescents" in Italy amid a COVID-19 outbreak in May 2020, for example, per the Guardian. Now, new research published in the British Journal of Dermatology is shining a light on what's been dubbed "COVID toe," suggesting it's a side effect of the body's attack response.

Researchers at the University of Paris studied 50 people with suspected COVID toe and 13 others with chilblain lesions unrelated to COVID-19, determining both types of lesions were caused by an immune response that generated high levels of certain autoantibodies, "which mistakenly target and react with a person's own cells and tissues as well as the invading virus," per the Guardian. Researchers also noted an antiviral protein called type 1 interferon and cells lining blood vessels were involved, per the BBC. The red or purple appearance of the affected area was attributed to vascular damage caused by COVID-19, reports the Independent.

"The confirmation of the cause will help to develop new treatments to manage it more effectively," UK podiatrist Dr. Ivan Bristow, who wasn't involved in the research, tells the Guardian. He notes many people see the condition clear up on its own, while others may require creams or drugs. A 13-year-old girl in Scotland who developed COVID toe previously told the BBC that she could barely walk and required a wheelchair to move significant distances. The condition appears to affect children and youth most often, perhaps because many children aren't yet eligible for COVID-19 vaccinations. "Presentations after vaccination are much rarer," dermatologist Veronique Bataille says. (More COVID-19 stories.)