A skin condition known as "Covid toes" may be a result of the immune system responding to the coronavirus, researchers report.
While the most common symptoms of Covid-19 include fever or chills, a cough, shortness of breath, headache, and fatigue, some patients over the past 18 months have also reported a chilblain-like rash developing on their feet and toes, and sometimes the fingers and hands.
Now, scientists have investigated what causes "Covid toes" and found a connection between the mechanisms behind both types involved an immune response "with high levels of certain autoantibodies as well as type I interferon, a key protein in the antiviral response."
In addition to the immune system, researchers noted the endothelial cells that line blood vessels also appeared to play a critical role in the development of "Covid toes" and chilblains.
"The epidemiology and clinical features of chilblain-like lesions have been extensively studied and published, however, little is known about the pathophysiology involved," said senior author Dr. Charles Cassius of Hôpital Saint-Louis in Paris, France. "Our study provides new insights."
Previously, experts at the British Association of Dermatologists reported that "Covid toes" seemed to be more common in younger people and typically appears later in the infection. It usually presents as red and purple bumps on the fingers and toes, with scaly patches often remaining during the recovery period.
Full study results have been published in the British Journal of Dermatology.