The skin condition known as Covid toes may be a side effect of the immune system's response to fighting off the virus, a new study has found.
The symptom results in chilblain-like inflammation and redness on the hands and feet, with the condition sometimes lasting for months at a time.
It typically develops within a week to four weeks of being infected and can result in toes and fingers becoming swollen or changing colour.
Senior author of the study, Dr Charles Cassius, said the research provided a deeper understanding of the condition.
"The epidemiology and clinical features of chilblain-like lesions have been extensively studied and published, however, little is known about the pathophysiology involved," he said.
"Our study provides new insights."
Researchers behind the study, which has now been published in the British Journal of Dermatology, examined 50 participants with Covid toes and 13 with similar chilblains lesions that arose before the pandemic.
They found one mechanism behind both types of the condition involved the body generating an immune response with high levels of certain autoantibodies.
They mistakenly target and react with a person's own cells and tissues as well as the invading virus.
They also found an overlap with type I interferon, a key protein in the antiviral response.
In addition to the immune system, cells lining blood vessels which supply the affected areas also appeared to play a critical role in the development of Covid toes and chilblains.
Medics have previously warned those who have had both Covid vaccine jabs that there are 21 symptoms they must still watch out for.
Experts are telling people it is crucial to stay vigilant and be aware of the signs they could still have Covid-19 - even if you have had both doses.
The symptoms include a high temperature, persistent cough, loss or change of taste/smell, muscle pains and red and sore fingers or toes.
