Matilda Gettins describes the COVID-19 symptom that is keeping us on our toes
“COVID toes” are a dermatological symptom of COVID-19. They “resemble chilblains”, which are red or purplish swellings one may experience if hands or feet are exposed to the cold for too long. They can feel itchy, cause pain or a sensation of burning. It is a widespread symptom. Over 200 articles in the Wiley Online Library have documented the phenomenon. However, it is not one of the 3 officially recognised symptoms (NHS guidelines).
During the first wave, a Spanish study examined data from 429 cases of dermatological symptoms associated with COVID-19 from 3 to 16 April 2020. Due to the low testing capacity available at the time, the study included both suspected and confirmed cases of COVID-19. It found “pseudo‐chilblains” in 19% of cases, including cases on both the fingers and toes. These symptoms were found to cause pain (32%), to itch (30%) or to give a burning sensation (11%). The study links the pseudo‐chilblains with COVID‐19 because dermatologists perceived an increased incidence of these lesions in a “warm weather period” and because “patients frequently had COVID‐19 contacts”. Additionally, of the 71 patients with pseudo‐chilblains, only one had a previous history of chilblains.
However, some scientists suggested that “COVID toes” might be related more to a change in lifestyle due to COVID restrictions, and not the virus itself. If children do not leave the house, but nonetheless fail to dress appropriately (e.g. not wear socks in the house) chilblains may occur even indoors.
To further investigate if the swellings could be related to COVID-19, a different team of scientists investigated biopsy samples from the blood vessel cells of the feet of seven children. These children exhibited the symptoms of COVID toes but had neither respiratory symptoms nor a positive result following nasal swab PCR tests. Yet under a specialized microscope, the scientists found coronavirus particles in the sample. The study did not test for antibodies.
COVID toes have also been documented worldwide. An International COVID-19 Dermatology Registry collected over 990 cases from 39 countries, and published findings based on this data in October 2020. It found COVID toes to last an average of 15 days, but that they could persist for “as long as 130-150 days”. The German Dermatology association’s website highlights that COVID toes are associated with late stages of infection while Dr. Paller of the American Academy of Dermatology (AAD) Association adds that it is unclear “whether you’re contagious when you have COVID toes”.
There are multiple other dermatological symptoms, such as hives and rashes, which have been recorded in association with COVID-19 infections, but whose correlation or potential causation remains insufficiently recorded. It will take more time and research until we have an accurate idea of the palette of symptoms that COVID-19 can cause.
To speed up this process, some scientists have started taking innovative methods, such as analysing social media posts for potential symptoms. But for now, we will just have to keep an eye out for new, emerging symptoms that may help give us more insight into this novel virus.