Loss of Taste and Smell From COVID-19 May Linger, Study Finds

As many as 1 in 4 Americans who experienced loss of taste and smell from COVID-19 had only partial or even no recovery from this symptom, according to a new study published in the journal The Laryngoscope.

Physicians from Massachusetts Eye and Ear in Boston examined 2021 data from a national health survey conducted by the Centers for Disease Control and Prevention (CDC) that included information about COVID-19 cases. Out of 35 million individuals who had COVID-19, 60 percent reported loss of taste or smell.

One year after infection, about 24 percent of those who’d experienced these sensory changes had not fully recovered, with 3 percent seeing no improvements at all. There were also cases where patients recovered their senses but only for a short time, known as sporadic recovery.

Neil Bhattacharyya, MD, one of the researchers behind the study, says that he and his colleagues at Eye and Ear saw a significant number of patients who experienced long-term sensory loss.

Loss of taste and smell was more common with the early coronavirus alpha and delta variants, Dr. Bhattacharyya notes. It has become one of the less common symptoms of COVID-19 with the rise of the current omicron variant, according to VCU Health.

Researchers Are Still Trying to Understand This Puzzling Symptom

It is unclear how COVID-19 can lead to the loss of taste and smell, but Bhattacharyya mentions three possible reasons.

First, he points out that many patients who lost their sense of smell had no other symptoms of COVID-19, suggesting that the virus had attacked the olfactory (scent) nerves in their noses.

The second theory is that the virus causes inflammation around the nerves in the sinuses or nasal cavities.

Lastly, it is possible that the virus attacks the blood vessels that connect to the nerves, cutting off circulation.

Treatment Options for Loss of Taste and Smell Are Scarce

Bhattacharyya says that there are no proven treatments for those who cannot recover their sense of taste and smell but, in his clinic, anecdotally, some therapies appear to help.

Oral steroids have had “marginal success” in cases he has witnessed, he says. He has also had positive results with smell retraining therapy. As the American Academy of Otolaryngology-Head and Neck Surgery describes it, this approach involves exposing a patient to various odors twice a day for several months to stimulate the olfactory system and establish a memory of those smells.

Bhattacharyya mentions one patient who could not taste cilantro or oregano despite an otherwise full recovery.

Smell and Taste Are Essential for Good Health and Quality of Life

Even though loss of taste and smell are no longer prevalent symptoms of COVID-19, more research is needed to understand the potential long-term impacts and devise effective treatments.

Impairment in smell and taste can lead to safety issues: People may be unable to determine if food has turned rancid, or if there’s a gas leak, for instance. Plus the inability to do something as simple as enjoy a meal with others can lead to social isolation.

“It can be a serious quality of life issue,” Bhattacharyya says. “When you multiply that across the population, it’s just a big problem we’re facing now that we’re coming out of the pandemic. Hopefully, some of the research people are doing will elucidate some forms of therapy for it.”