Filenews 9 June 2021
As has been written many years ago, the main signs of COVID-19 infection are fever, cough, fatigue and loss of taste and smell, while some skin symptoms are also observed. But there is another part of the body on which the coronavirus seems to affect: the nails.
As scientists Vasilios Vassiliou, lecturer in Cardiovascular Medicine and medical researchers at the University of Southern England Nikhil Aggarwal and Subothini Sara Selvendran report in a study published in The Conversation, in a small number of patients with COVID-19 infection, the fingernails appear discoloured or deformed a few weeks later - a phenomenon often called 'COVID nails'.
A symptom is a red crescent pattern that forms a curve over the white area at the base of the nails. This phenomenon appears to exist before other symptoms of COVID-19, with patients noticing it less than two weeks after diagnosis.
"Such patterns are generally rare and until now had not been observed so close to the base of the nails, so the appearance of such a pattern could be an exclusive indication of coronavirus infection," the experts point out.
The mechanism behind this crescent pattern remains unclear, however. One possible cause could be damage to blood vessels associated with the virus itself. Alternatively, it may be due to excessive immune response that causes small blood clots and discoloration. The important thing is that these signs do not appear to be worrying, as patients are otherwise asymptomatic - although it is not clear how long they will remain so, with cases so far reported from one to four weeks.
Signs of physical stress
In addition, some patients have noticed new horizontal streaks at the base of the nails of their hands and feet, known as Beau lines, which tend to occur four or more weeks after COVID-19 infection.
Beau lines occur when there is a temporary disorder in nail growth due to physical stress, such as an infection, malnutrition or side effects of treatments such as chemotherapy. "Although it is likely to be caused by COVID-19, it is certainly not an exclusive symptom of it," the scientists stress.
As the nails grow on average 2-5mm each month, beau lines tend to become visible four to five weeks after the onset of physical stress –as the nails grow, the streak is revealed. The time of a stressful event can therefore be estimated by considering how far the Beau lines have been removed from the base of the nails. There is no specific treatment and eventually they leave on their own when the underlying condition is cured.
Other unusual findings
The two above are the most common nail marks associated with COVID-19. But the researchers have also recorded some other unusual evidence.
For example, a patient's nails loosened and eventually fell three months after she was infected with the virus. This phenomenon, known as onych grouping, is thought to occur for similar reasons to the appearance of Beau lines. The patient did not receive treatment for these changes, as healthy nails slowly appeared underneath, indicating that the problem would be solved on its own.
Another patient, 122 days after the positive diagnostic result for COVID-19, noticed orange discoloration on the nail tips. In this case, no treatment was given either, but the discoloration had not gone away after a month, with the underlying mechanism of this condition remaining unknown.
In a third case, a patient had horizontal white lines on his fingernails, which did not disappear with pressure and which are known as "Mees lines" or "leukonygia". They appeared 45 days after the diagnosis of coronavirus, but tend to leave on their own with the raising of the nails, which is why they do not require treatment. Mees lines are thought to be caused by abnormal production of proteins in the nails due to systemic disorders.
For now, the mystery remains.
"Although COVID-19 infection precedes all three of these conditions, we have only a few patients to examine in each case and therefore it is not yet possible to say whether they are actually caused by the disease," the scientists say, adding:
"Even in the case of the Beau lines and the red crescent moon pattern, we still have a long way to go to confirm a definitive link between these changes and COVID-19 as well as the mechanisms behind them. So we need many more incidents before we can say with certainty that there is indeed a connection."
According to experts, if there is ultimately a causal link, it is important to remember that not all COVID-19 sufferers experience such symptoms in the nails and that such abnormalities do not necessarily mean that someone is ill.
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