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Researchers have conducted a large-scale study showing that COVID-19 has more serious and lasting effects on the sense of smell than previously thought. Even patients without obvious smell problems experienced significant impairment of olfactory receptors. This raises concerns, as loss or weakening of smell can pose risks to health and safety.
The study, led by the RECOVER initiative of the U.S. National Institutes of Health in collaboration with NYU Langone Health, found that most people who had COVID-19 develop hyposmia, a reduced ability to detect odors.
“Our results confirm that people with a history of COVID-19 are particularly at risk of reduced smell, which often goes unnoticed,” said co-author Laura Horwitz.
The research involved 3,535 participants. Notably, 80% of those who noticed changes in smell after illness scored poorly on clinical smell tests even two years later, with 23% experiencing severe impairment or complete loss of smell. Surprisingly, 66% of participants who had not reported any issues also scored abnormally low.
The University of Pennsylvania Smell Identification Test (UPSIT) was used, offering 40 different scents to assess both the presence and degree of olfactory impairment.
Hyposmia can seriously reduce quality of life, prevent detection of hazards like gas, smoke, or spoiled food, and may contribute to depression. It can also be an early symptom of neurological diseases, including Parkinson’s and Alzheimer’s.
Unlike earlier studies based on self-reported data, this research used standardized clinical testing, making it the most comprehensive to date.
“These findings suggest that healthcare providers should consider smell testing as a standard part of post-COVID care. Even if patients don’t notice problems immediately, impaired smell can have serious physical and mental health effects,” Horwitz explained.
Researchers are now exploring potential ways to restore smell, including vitamin A treatment and smell training exercises to help the brain relearn odor recognition.
Meanwhile, in Ukraine, the respiratory illness season is beginning, and health officials continue to urge vaccination against COVID-19.
