Altered sense of taste present in half of COVID-19 cases

Analysis could provide another clue for diagnosing the illness

Nearly half of individuals who contract COVID-19 experience changes in their sense of taste, a new analysis led by a University of Toledo researcher has found.

The systematic review, published in the journal Gastroenterology, could provide yet another diagnostic hint for clinicians who suspect their patients might have the disease.

"Earlier studies didn't note this symptom, and that was probably because of the severity of other symptoms like cough, fever and trouble breathing," said Dr. Muhammad Aziz, chief internal medicine resident at UToledo and the paper's lead author. "We were beginning to note that altered or lost sense of taste were also present, not just here and there, but in a significant proportion."

Aziz and his research collaborators analyzed data from five studies conducted between mid-January and the end of March. Of the 817 patients studied, 49.8% experienced changes to their sense of taste. Researchers suspect the true prevalence could be even higher because some of the studies were based on reviews of patient charts, which may not have noted every symptom.

"We propose that this symptom should be one of the screening symptoms in addition to the fever, shortness of breath and productive cough. Not just for suspected COIVD patients, but also for the general population to identify healthy carriers of the virus," Aziz said.

Prior research has found that a significant number of people who have COVID-19 don't know they've been infected and may be spreading the virus.

Aziz and his research collaborators suspect an altered sense of taste is more prevalent in patients with minor symptoms, though more studies are needed to validate that suspicion. Even so, changes in an individual's sense of taste could be a valuable way to identify carriers who are otherwise mostly asymptomatic.

Taste disorders are tied to a variety of viral illnesses. The review did not attempt to identify the reason that COVID-19 is causing changes in patients' sense of taste; however, researchers theorize it could be COVID-19's ability to bind to what's known as the ACE-2 receptor, which is expressed in epithelial cells on the tongue and mouth.

Because the novel coronavirus was unknown prior to its emergence in January, scientists have been moving rapidly to learn more about both the virus and the disease it causes.

Aziz said the drip of new information shows the need for more scientists to dig into the impacts of COVID-19.

"A lot of things are being missed, which is why I think researchers from every field should try to look into this and see if it's affecting their specialty in one way or another," he said. "Who knows what systems this virus is affecting. If we can catch it earlier in the disease course, we can prevent the spread of the virus and potentially have ways of managing it."