By David Levine
This article is based on reporting that features expert sources.
THIS FIRST THING ABBE Piels noticed when she bit into a piece of avocado toast was that she couldn’t taste it. She could feel the heat of the Sriracha sauce on it, but she couldn’t sense any flavor.
The same thing occurred when the 19-year-old college freshman tucked into a bowl of Cinnamon Toast Crunch cereal. “My brother said it smelled good, but I couldn’t smell anything,” says Piels, who was home in Livingston, New Jersey, after her school, the University of Rochester, went to distance learning due to the coronavirus. “I could tell if something was sweet, salty or spicy, but I couldn’t taste the flavor.” Similarly, she could sense the sting of hand sanitizer but not its antiseptic smell. Even her favorite perfume was undetectable.
And that compounded the worry her family was already experiencing, as her father was in the hospital suffering from COVID-19. “My mom told me loss of taste and smell was a symptom of the coronavirus,” Piels says. “It was pretty scary.”
Piels, who was not tested for the coronavirus, had no other symptoms except for fatigue, and that improved in a week or so. Her father, who also lost his sense of smell, has since recovered and is back home. But the experience for her was, in a word: “weird.” Piels says the loss of her sense of taste and smell had an impact. “It took a toll on me emotionally, especially when food should be bringing us all happiness when we are stuck alone in our houses,” she says. “I would bake and eat, but couldn’t even get that satisfaction from sweets or a good meal.”
Of course, Piels was fortunate not to have any serious complications of the coronavirus. But her experience highlights one of the more common, if somewhat unusual, symptoms of this disease.
Smell Plus Taste Equals Flavor
A lost sense of smell, known medically as anosmia, is increasingly being noted as a symptom of the coronavirus. This is not surprising, according to the American Academy of Otolaryngology–Head and Neck Surgery, which says that “viral infections are a leading cause of loss of sense of smell, and COVID-19 is caused by a virus.”
Indeed, it’s not unusual to lose sense of smell with any viral infection in the nose, including other coronaviruses that cause the common cold. The academy says that a group of otolaryngologists in the U.K. noted that 2 out of 3 confirmed COVID-19 cases in Germany reported a loss of sense of smell and 30% of people in South Korea with mild symptoms who tested positive for COVID-19 reported anosmia as their main symptom.
Taste, however, is another issue. “The definition of taste to a patient and to a physician are very different,” said Dr. Joseph K. Han, professor of otolaryngology, director of the division of rhinology and endoscopic sinus-skull base surgery and director of the division of allergy at Eastern Virginia Medical School.
“Physicians talk about the five taste sensations,” he says, meaning the sweet, sour, salty, bitter and umami tastes recorded by taste buds in the mouth. Viruses don’t typically affect those senses directly. “Losing sense of taste is from a completely different nerve system, a different disease process,” says Han, who doesn’t see how coronavirus would affect taste directly, but researchers are looking into it.
Yet, even if the sense of taste is not altered, smell has a direct effect on how we perceive the flavor of foods, Han says – just as Piels described it. “We should use the term sense of flavor, because flavor isn’t taste, it is smell,” Han says.
Sense of Smell Usually Returns
How does this coronavirus disrupt the sense of smell? “There are three leading theories,” says Steven Munger, director of the University of Florida Center for Smell and Taste, located within UF’s McKnight Brain Institute.
The first is that the virus is using the olfactory nerve to transfer across the skull into the brain. The second suggests the virus is attacking sensory cells themselves, “damaging or mucking up the works,” Munger says. The third possibility is that the virus is attacking nasal tissues more generally, causing inflammation or other disease processes that interfere with normal smelling function.
This last idea gained support recently. “A short study analyzed gene expression data in nasal tissue and found two genes that code for this class of viruses, which suggests a more global inflammatory response,” Munger says. He adds that patients are reporting they get their sense of smell back after a few weeks, “which would be consistent with the type of smell loss with any upper respiratory infection.”
Piels added another data point to that observation. About three weeks after her disappointing avocado toast and bland breakfast cereal, she says her sense of smell and taste “are 100% back now.”
Smell Loss as Screening Tool
Because this symptom is so widely reported, the American Academy of Otolaryngology–Head and Neck Surgery recommended on March 22 that anosmia be added to the list of COVID-19 symptoms used to screen people for possible testing or self-quarantine.
Munger says that if you suddenly feel like you can’t smell or taste, you should act as though you are infected with coronavirus: Self-isolate and immediately call your physician, or one of the various hotlines set up for reporting COVID-19.
According to Munger, scientists and clinicians around the world who study smell and taste are working together to fast-track data collection on this symptom of COVID-19 and to develop tests patients can do at home.
“It’s important that we quickly get real data measuring sense of smell in people with COVID, so we can understand how common a symptom this might be,” he said. “If it’s common enough, then we could use it as part of screening protocol. Like fever or cough or other symptoms that are not unique to COVID, smell loss could be incorporated in screening patients from a safe distance.”