Temporary loss of smell emerged as a common indicator of COVID-19 early in the pandemic. Research into the cause and treatment of the condition, known as anosmia, is ongoing, though recent studies have brought us one step closer to answers.
Two latest findings on COVID-19-related anosmia:
1. Loss of smell and taste is becoming less common as the virus evolves, according to researchers.
The Monell Chemical Senses Center in Philadelphia received a flood of inquiries from patients during the pandemic's first two years, according to Valentina Parma, PhD, a psychologist at the center.
"Our inboxes are not as flooded as they used to be," she told Nature in early June.
A study published May 3 in Otolaryngology-Head and Neck Surgery may help explain why. Researchers analyzed the outcomes of more than 616,000 U.S. COVID-19 survivors and found those infected with the alpha variant were half as likely to experience loss of smell or taste compared to those infected with the original coronavirus strain. This figure dropped to 44 percent for the delta variant and just 17 percent for omicron.
2. Smell and taste hasn't fully returned for many people who contracted COVID-19 early in the pandemic, research shows.
In a separate study published in the journal Rhinology, researchers tracked the outcomes of 100 people who had mild cases of COVID-19 between March and April of 2020. More than a year after their recovery, 46 percent of study participants still had smell issues, compared to 10 percent of people in a control group who lost their sense of smell for other reasons. Another 7 percent of COVID-19 survivors still had total smell loss a year after contracting the virus.
Based on these findings — and considering that more than 500,000 million COVID-19 cases have been confirmed globally — Nature suggests that tens of millions of people may be grappling with long-term smell issues.
Scientists are still working to understand the cause and potential treatment for these issues via ongoing clinical trials. For now, most researchers point to smell training as a potentially effective treatment for patients with partial smell loss. The treatment entails having patients try to identify strong scents to restore olfactory signaling, according to Danielle Reed, PhD, a geneticist at Monell Chemical Senses Center.
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