COVID-19 causes taste loss in about 4 in 10 infected people, study finds

Feb. 15 (UPI) -- Researchers at at independent research center in Philadelphia have estimated the prevalence of COVID-19 taste loss, which it says scientists have underrated as a symptom because it's closely linked with smell loss.

Scientists have been skeptical of COVID-19 patients reporting taste loss because it could be confused with smell loss, and taste loss was rare before COVID-19.

But the largest study undertaken to date has found that the taste loss is genuine, a statement on the study by the Monell Chemical Sense Center said.

"About four in every 10 COVID-19 patients experience some form of taste loss," said Mackenzie Hannum, a postdoctoral fellow in the lab of scientist Danielle Reed.

Reed added that "it is time to turn to the tongue" to understand why taste is affected and learn how to reverse or repair that loss.

The study recently published in Chemical Senses reviewed data from 241 studies between May 15, 2020, and June 1, 2021, an unprecedentedly large number of articles for a single analysis.

Researchers analyzed the taste dysfunction in its three different forms, including ageusia, total taste loss, partial taste loss and taste distortion.

The 241 studies included 138,785 COVID-19 patients, and among those patients, 32,918 -- or 37% -- experienced some form of taste loss.

The research team also found that middle-aged individuals, ages 36 to 50, had the highest prevalence of taste loss, and that women were more likely to lose the sense of smell than men.

Studies included self-reports or direct reports of taste loss.

"Self-reports are more subjective and can be in the form of questionnaires, interviews, health records, for example," Hannum said in the statement.

"On the other hand, direct measures of taste are more objective. They are conducted using test kits that contain various sweet, salty, and sometimes bitter and sour solutions given to participants via drops, strips or sprays."

While direct tests were expected to be more reliable, researchers found that the prevalence remained the same whether a study used direct measures or self reports.

"Here self-reports are backed up by direct measures, proving that loss of taste is a real, distinct symptom of COVID-19 that is not to be confused with smell loss," study co-author Vicente Ramirez, a visiting scientist at Monell and a doctoral student at the University of California-Merced, said in the statement.