A. TL;DR. Some COVID-19 survivors have noticed that their fingernails have developed horizontal grooves.
While these nail markings do not occur in all COVID-19 patients, they could be caused by a temporary interruption in nail growth. These changes are not permanent and nothing to worry about.
We continue to learn new things about COVID-19, which sometimes includes adding to a list of curious symptoms such as COVID nails, COVID toes, and hair loss. Some patients have noticed that their fingernails acquired horizontal grooves a few weeks after they recover from COVID-19. This type of marking (known as Beau’s lines) can be due to a stress to the system (e.g., symptoms associated with COVID-19). Similarly, physical or emotional stress can cause hair loss, a process known as telogen effluvium. Since nail and hair growth are not necessary for survival, the body shifts to focus on what is most important at the time. The long-term consequences of these changes in fingernails and hair growth are minimal.
Links to articles and a case study: