Long-Term Effects of COVID-19 on the Sense of Smell

Amid the ongoing COVID-19 pandemic, scientists continue to uncover long-term effects that may not be immediately apparent upon infection. Among these effects, the loss of the sense of smell emerges as a symptom that persists for a prolonged period in some survivors of the virus. A recent study has shown that this phenomenon might be more common than previously thought.

New Study Reveals Decline in Sense of Smell

Thanks to the efforts of the RECOVER initiative by the National Institutes of Health, in collaboration with the NYU Langone Health Clinical Science Center, the relationship between COVID-19 and the loss of smell, medically known as anosmia, was examined. The study revealed that about 80% of people who reported a change in their sense of smell after contracting the virus scored poorly in a clinical smell test conducted nearly two years post-infection.

Even more surprisingly, 66% of participants who tested positive for COVID-19 and did not report any smell issues showed abnormal results in the test.

The Importance of Smell in Daily Life

The sense of smell is an essential part of human safety and well-being. Individuals suffering from anosmia may find it challenging to detect hazards such as spoiled food, gas leaks, or smoke. Additionally, this condition is linked to weight loss, depression, and a general decline in quality of life.

Moreover, the loss of smell can be an early warning sign of certain neurodegenerative diseases like Parkinson’s and Alzheimer’s, as these diseases affect brain areas involved in processing odors.

Objective Assessment of Smell Loss

Most previous studies relied on self-reported accounts of smell loss after COVID-19, which may not be entirely reliable. To address this, the team used a standardized clinical tool known as the University of Pennsylvania Smell Identification Test (UPSIT).

In this test, participants identify 40 different odors through multiple-choice options, with each correct answer earning one point. The final score is compared to data from thousands of healthy volunteers of the same gender and age.

Researchers and Methodology

The study was led by Dr. Leora Horwitz and Dr. Jacqueline Becker, alongside a team of researchers from various institutions such as Howard University, Massachusetts General Hospital, and the University of Arizona. The research involved more than 3,535 adults and was published in JAMA Network Open, making it the largest investigation to date assessing long-term smell loss after COVID-19 using an objective method.

Conclusion

This study confirms that the loss of the sense of smell may be more widespread than previously believed, requiring greater attention from healthcare providers as part of post-COVID-19 care. Loss of smell is not just a sensory issue; it can impact mental and physical health overall. Experts are currently exploring ways to restore the sense of smell after COVID-19 infection, such as vitamin A supplements and smell training to retrain the brain’s response to odors.