An example of “covid nails” that has been observed by Tim Spector, principal investigator for the Zoe COVID Symptom Study. (Tim Spector/Zoe COVID Study)

At this point in the pandemic, the coronavirus’s devastating effects on the human body have been well documented. But unusual symptoms that may be connected to the virus continue to crop up, including “covid toes,” “covid tongue” and hair loss.

Now, news reports and social media posts have documented visible changes in the nails of some covid-19 survivors, most commonly in the form of horizontal grooves. Dubbed “COVID nails” by a U.K.-based epidemiologist who tweeted about the markings earlier this month, the anecdotal reports have prompted assertions that it could be a way to tell whether you’ve had the virus.