Anecdotal evidence suggests that the coronavirus omicron variant may be less likely than other variants to cause smell loss, a common Covid-19 symptom with potentially serious implications for brain function, according to a paper published May 3 by Otolaryngology–Head and Neck Surgery.
Compared to the original coronavirus strain, risk of smell and taste loss appears 50% lower for the alpha variant, 66% lower for the delta variant and 83% lower for the omicron variant, Virginia Commonwealth University researchers said.
These results are “very good news,” indicating that new variants will put Covid-19 patients at much lower risk of smell and taste loss, said Dr. Daniel Coelho, lead author of the paper, in a statement.
Covid-19-associated smell loss has been linked to depression symptoms and dementia, so smell loss shouldn’t be treated as a minor symptom, Coelho said.
While loss of smell and taste is still a likely sign of Covid-19 infection, the reverse is no longer true, so people shouldn’t assume they don’t have the virus just because their senses of smell and taste are working normally, Coelho said.
Researchers analyzed data from 616,318 Covid-19 patients gathered by variant-tracking project CoVariants.
“This is not just about being able to enjoy a fine bottle of wine again; it’s about safety and preserving your quality of life,” Coelho said in a statement.
During the first two years of the pandemic, smell loss was one of the strongest indicators of Covid-19 infection, affecting 60% of people age 16-65 who caught the disease, according to the COVID Symptom Study, a U.K.-based research initiative. An April JAMA Neurologystudy found that Covid-19 smell loss was associated with damage to a part of the brain that processes smell. Damage to axons—the parts of nerve cells that transmit signals to other cells—was about 60% more severe among patients with Covid-19 than among patients without the disease, researchers found, suggesting that Covid-19-associated smell loss may be permanent.
WHAT WE DON’T KNOW
It remains unclear how Covid-19 causes smell loss. The authors of the JAMA Neurology study concluded that damage to the brain wasn’t caused directly by the virus, and might have been caused indirectly by inflammation to the area. Numerous treatments for Covid-19 smell loss are currently under testing, ranging from inserting plasma-saturated sponges up the nose to taking anti-inflammatory drugs. Coelho and other Virginia Commonwealth University researchers are working on an olfactory implant that would aim to restore smell loss like a cochlear implant restores hearing loss.
1.6 million. That’s about how many Americans had long-term Covid-19-associated smell loss as of November, according to Smithsonian Magazine.