Increasing evidence suggests that a lost sense of smell, known medically as anosmia, may be a symptom of COVID-19. This is not surprising, because viral infections are a leading cause of loss of sense of smell, and COVID-19 is a caused by a virus. Still, loss of smell might help doctors identify people who do not have other symptoms, but who might be infected with the COVID-19 virus — and who might be unwittingly infecting others.
A statement written by a group of ear, nose and throat specialists (otolaryngologists) in the United Kingdom reported that in Germany, two out of three confirmed COVID-19 cases had a loss of sense of smell; in South Korea, 30% of people with mild symptoms who tested positive for COVID-19 reported anosmia as their main symptom.
On March 22nd, the American Academy of Otolaryngology–Head and Neck Surgery recommended that anosmia be added to the list of COVID-19 symptoms used to screen people for possible testing or self-isolation.
In addition to COVID-19, loss of smell can also result from allergies as well as other viruses, including rhinoviruses that cause the common cold. So anosmia alone does not mean you have COVID-19. Studies are being done to get more definitive answers about how common anosmia is in people with COVID-19, at what point after infection loss of smell occurs, and how to distinguish loss of smell caused by COVID-19 from loss of smell caused by allergies, other viruses, or other causes altogether.
Until we know more, tell your doctor right away if you find yourself newly unable to smell. He or she may prompt you to get tested and to self-isolate.
Source: Harvard Medical School, USA