Risk of smell loss from COVID-19 has plummeted since 2020

When the pandemic began, losing your sense of smell was considered a key indicator of COVID-19, and the condition affected about half of those who tested positive for the coronavirus. However, a new study reveals that the chance of smell loss from the latest omicron variants is as low as 6 to 7 percent of what it was in the early days of the pandemic.

"So now, three people out of 100 getting COVID presumably may lose their sense of smell, which is far, far less than it was before," said study leader Evan Reiter, the medical director of Virginia Commonwealth University Health's Smell and Taste Disorders Center.

The findings, published in the journal Otolaryngology - Head and Neck Surgery, mean that losing smell and, by association, your sense of taste is no longer a reliable sign that someone has a COVID infection, Reiter said.

"Now, the chance of you having COVID as opposed to another virus, like different cold and flu bugs, is about the same," he said.

Although it is unclear why the frequency of smell loss has decreased over time, vaccinations and preexisting immunity could be playing a role, the researchers said.

Doctors have had difficulty explaining the cause of smell loss, but some research suggests it is due to COVID triggering a prolonged immune assault on olfactory nerve cells. These cells sit at the top of the nasal cavity and help send smell signals from the nose to the brain.

It is possible that over time this attack causes a decline in the number of olfactory cells. But if you've already been infected or vaccinated, the time the virus has to inflict this kind of damage is dramatically reduced, said Benjamin tenOever, a professor of microbiology and medicine at New York University who was not involved in the study.

Smell loss is still taking a toll

To determine the frequency of smell and taste loss throughout the pandemic, researchers accessed a national database of more than 7 million patients who tested positive for the coronavirus from April 2020 to October 2022. Using the early 2020 levels as a baseline, they calculated the relative risk of smell and taste loss during peak infection periods for each variant wave.

The study found the risks of smell and taste loss for alpha and delta, two of the most widespread coronavirus variants in 2021, were only 74 and 64 percent, respectively, compared to the first pandemic wave. When omicron variants were dominant in 2022 and early 2023, the risk of smell loss plummeted to as low as 6 percent of the baseline.

Despite the dramatic decline, Reiter said he still sees patients who have either completely lost or have a distorted sense of smell, which takes a significant toll on their quality of life.

"By and large, the biggest complaint people will have with any kind of distortion or loss of their sense of smell is that food doesn't taste the same," Reiter said. This is because your taste buds tell you if the food is sweet, sour, bitter or salty, but your nose tells you the specifics from the odors you inhale, such as if you're eating an apple or a pear.

People with a distorted sense of smell, known as parosmia, may find that the foods they once liked taste and smell revolting.

"People can force themselves to keep up their calories if what they're eating is just very bland and they don't get any taste," Reiter said. "But if it's a really kind of a repulsive taste, then that's literally and figuratively harder to swallow, right?"

How to retrain the nose

Do-Yeon Cho, the director of the Smell and Taste Clinic at the University of Alabama at Birmingham, said that "until you lose your sense of smell, you totally don't understand how important smell is."

For those experiencing smell loss without access to a smell and taste clinic, Cho recommends smell training at home twice a day with essential oils. Proponents say that sniffing at least four core scents - fruity, flowery, spicy and resinous - can help restore the neural connections between the nose and brain.

"Just pretend you're in the Zen place, like near the ocean, and try to smell each oil for at least about 30 seconds," repeating the process for two minutes in the morning and again at night. Consistency is key to regaining sensation, he added.

The vast majority of people with COVID-induced smell loss regain the sensation after three months. But Cho's patient Alexas Brewer struggled with smell loss for nearly three years before she recovered. In December 2020, Brewer was teaching Asian and Italian cooking classes at Williams Sonoma in Birmingham, Ala., when she began experiencing symptoms. At the company, Brewer also was working in sales and management, which she later relied on once the cooking classes were canceled because of a change in COVIDprotocol.

"It was still really hard because we still did tastings and sold fragrances," said Brewer, "but I wasn't really able to participate in that."

Cho said that the most important part of smell retraining is listening to how his patients feel, because smell loss can have psychological repercussions. Because of the rarity of smell loss that lingers for years, Brewer began to feel misunderstood and isolated. For patients who, as she did, lost their smell and taste during earlier COVID waves, these feelings may be exacerbated by the steep decline in prevalence, she said.

"The [new study] is about how less people have smell loss from COVID , which I thank God for," Brewer said. "But it means that the people who had original COVID and lost their smell are kind of separated from all the people who have COVID now."

Individuals with sensory deficits should seek out community and not let frustration or perceived defeat deter them from obtaining treatment, she said.

"I don't even want to tell people who are going through this to not give up, because it's almost impossible not to," Brewer said. "But don't give up in the long run. Just keep trying."