COVID nails: a sign you may have had the virus before

The symptoms of COVID started off with the usual fever, headache, and shortness of breath. But as time has passed, they have been getting stranger—the latest being COVID nails.

Professor Tim Spector has been tracking COVID symptoms as the principal investigator of the Zoe COVID Symptom Study app. He recently shared a photo of this unusual new symptom and talked about why so many people have been experiencing this phenomenon.

What are COVID nails?

COVID nails are officially known as Beau’s lines. You know you have this condition when you start to see horizontal indents or transparent lines in your finger and toe nails. How did those lines get there? An injury or sickness can halt the natural growth of nails temporarily. Upon recovery, nails start growing once again but they leave behind a noticeable dent in the process.

Normally these lines will appear in a whole range of illnesses, but with the rising cases, more and more COVID patients are beginning to report this symptom. In fact, the lines have frequently been associated with high fever, one of the leading symptoms of COVID. Spector tweeted:

Yes—any illness can provoke them—it’s not specific to COVID—but clearly a lot of people were exposed at a similar time.

A sign you may have had COVID

Spector added that this is a fairly harmless symptom and it shouldn’t be taken as a definite sign of COVID infection. According to a paper published in the Canadian Medical Association Journal, it takes around two to three weeks for patients to notice the dent after getting infected. So, don't rely on this sign to tell you whether you're COVID-positive.

However, given that it takes six months for these lines to fully grow out, it might be able to tell you whether or not you had asymptomatic COVID in the past couple of months.