Scientists believe they can finally explain the skin condition known as ‘Covid toes’.
Alongside common symptoms, such as a dry cough or high fever, some people have also developed small, itchy, red patches on their feet.
Findings from new research, published in the British Journal of Dermatology, show ‘Covid toes’ may be a side effect of the immune system’s response to fighting off the virus.
It results in chilblain-like inflammation and redness on the hands and feet, with the condition sometimes lasting for months at a time.
The symptom typically develops within a week to four weeks of being infected, and can result in toes and fingers becoming swollen or changing colour.
Researchers now hope their findings may help with treatments to ease the symptoms.
They examined 50 participants with ‘Covid toes’ and 13 with similar chilblains that arose before the pandemic.
Cells lining blood vessels, which supply the affected areas, were found to play a critical role in the development of both conditions.
Senior author, Dr Charles Cassius, said the research provided a deeper understanding of the condition.
He said: ‘The epidemiology and clinical features of chilblain-like lesions have been extensively studied and published, however, little is known about the pathophysiology involved.
‘Our study provides new insights.’
What are ‘Covid toes’?
They are typically red and swollen, and can become purple over time. They can also blister.
It can happen at any age, but affects children, teenagers and young people more commonly.
For some, it is painless, but the rash can be extremely sore and itchy, with tender blisters and swelling.
Consultant pathologist Dr Clare Craig said having red toes is now one of the biggest signs of Covid infection.
According to a New England Journal of Medicine (NEJM) paper, if someone has red bruises on their feet, they have a 72.14% chance of testing positive.
This is compared with 65.22% for a dry cough and 74.69% for chest pain and tightness.