A new large-scale study has confirmed that people who feel their sense of smell has weakened after Covid-19 are likely correct—and the problem may be more widespread than many realize.
Even those who believe their sense of smell is normal may be unknowingly impaired, researchers say.
The study, published in JAMA Network Open, was led by the National Institutes of Health’s RECOVER initiative and drew on data from more than 3,500 adults across the United States. Participants, both with and without a history of Covid-19, completed an objective smell test known as the University of Pennsylvania Smell Identification Test (UPSIT).
This clinical “scratch-and-sniff” exam asks individuals to identify 40 distinct scents.
Results showed that 80% of participants who reported a loss or change in smell after Covid-19 scored poorly on the test even two years later. Among them, nearly one in four were found to be severely impaired or had lost their sense of smell entirely.
Surprisingly, two-thirds of those who had been infected but did not report any problems also scored abnormally, suggesting that many cases of smell dysfunction go undetected.
“This work shows that people with a history of Covid-19 are at higher risk for long-term damage to their sense of smell,” said Dr. Leora Horwitz, lead author of the study and professor at NYU Grossman School of Medicine. “Because the condition is often unnoticed, it remains underrecognized in clinical care.”
Smell loss, or hyposmia, is more than a nuisance. It has been linked to depression, weight loss, and reduced quality of life, while also posing safety risks since those affected may miss signs of dangers such as spoiled food, gas leaks, or smoke.
Researchers also note that changes in smell can signal early stages of neurological diseases like Alzheimer’s and Parkinson’s.
The findings suggest doctors should consider routine smell testing in long-term Covid care, using objective methods rather than relying on self-reporting. Meanwhile, scientists are testing potential recovery treatments, including vitamin A supplements and “smell training” to help the brain relearn odors.
“This is not just about sensing pleasant smells,” Horwitz emphasised. “It’s about health, safety, and quality of life.”
– Ends