Study suggests ‘COVID toe’ may be the side effect of an immune response

A skin condition referred to as ‘COVID toe’ is believed to be the body’s immune response to fighting the virus, according to a study.

The condition, which causes symptoms similar to chilblains, with redness and inflammation, also causes fingers and toes to become swollen or to change colour.

A study from the British Journal of Dermatology examined 50 participants with the condition and 13 with similar lesions that occurred before the pandemic.

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According to researchers from the University of Paris the study found the condition was likely caused by the body generating an immune response with high levels of certain autoantibodies, which accidentally target a person’s cells and tissues as well as the virus.

In addition to the immune system, cells lining blood vessels that supply the affected areas also appeared to play a critical role in the development of COVID toes and chilblains.

COVID toe can happen at any age but seems to most commonly affect children and teenagers.

While it’s usually painless, the rash can also be extremely sore and itchy, with tender blisters and swelling, causing some to barely able to walk or wear shoes.

It typically develops within one to four weeks of being infected and can last up to months at a time. 

In May 2020, the European Journal of Pediatric Dermatology reported an “epidemic” of “red or purple lesions on the side or sole of the foot or on hands and fingers among children and adolescents in Italy.

It said that, unlike other rashes associated with coronavirus, it had not been previously observed. 

The rash appeared to be one of the main symptoms of the virus at the beginning of the pandemic, sometimes occurring as the only symptom of positive cases.

Dr Veronique Bataille, a consultant dermatologist and spokesperson for the British Skin Foundation, told the BBC that COVID toe was seen very frequently during the early phase of the pandemic but had been less common in the current Delta variant wave.

She said it might be due to more people being vaccinated or having some protection against the virus from past infections: “Presentations after vaccination are much rarer.”