#USA #New York #NYU Langone #COVID-19 #Hyposmia

Uncovering the Hidden Impact of COVID-19 on Smell

A new research from NYU Grossman School of Medicine sheds light on a potentially lingering consequence of COVID-19: the loss of smell. Although many might overlook olfactory changes after recovery, a significant percentage of those who had COVID-19 experience a notable reduction in smell capabilities, according to a comprehensive study published in the journal JAMA Network Open on September 25, 2025.

The study, part of the National Institutes of Health's RECOVER initiative, utilized a robust 40-odor assessment designed to objectively measure olfactory function among 3,535 participants. Researchers discovered that a staggering 80% of individuals who reported changes in their smelling ability after contracting the virus achieved low scores on the scent-detection test conducted roughly two years post-infection. Alarmingly, 23% of these individuals were found to be severely impaired or had completely lost their sense of smell.

Notably, even among those who believed they had not experienced olfactory issues, 66% of participants still scored inadequately on the test. Dr. Leora Horwitz, the co-lead author and a prominent figure in the Departments of Population Health and Medicine at NYU, emphasized, "Our findings confirm that those with a history of COVID-19 may be especially at risk for a weakened sense of smell, an issue that is already underrecognized among the general population."

Moreover, the results revealed that even 60% of uninfected participants, who claimed no olfactory difficulties, also recorded poor evaluation scores. This raises questions regarding the awareness and understanding of hyposmia—a condition marked by diminished smelling ability—which has been associated with various health issues, including weight loss, a poor quality of life, and depressive symptoms. Experts indicate that a reduced sense of smell can hinder the detection of critical dangers, such as spoiled food or harmful gas.

The implications of these findings stretch beyond immediate health concerns. Research indicates that smelling dysfunction could serve as an early red flag for neurodegenerative disorders like Parkinson's or Alzheimer's disease, which affect the brain's sensory processing areas. Previously, studies often relied on subjective patient reports to assess smell, which can lack reliability regarding the ailment’s severity and duration. This current research marks a significant advancement in understanding post-COVID olfactory impacts.

The study's rigorous methodology included consistent evaluations of participants, both COVID-positive and negative, every 90 days from late 2021 to mid-2025. The clinical measurement employed was the University of Pennsylvania Smell Identification Test (UPSIT). Participants faced a scratch-and-sniff test with 40 distinct scents and assessed their performance against a healthy volunteer database.

Given these revelations, Dr. Horwitz advocates for routine olfactory assessments during post-COVID evaluations. She notes, "While patients might not notice right away, a dulled nose can profoundly affect their mental and physical well-being."

In an effort to combat these long-term effects, researchers are investigating potential rehabilitation options, including vitamin A treatments and olfactory training programs aimed at retraining the brain’s odor responses. Dr. Horwitz underscores the need for deeper insights into how COVID-19 affects sensory and cognitive systems to improve therapeutic efficacy.

However, it's important to note that this study did not directly evaluate taste loss, which frequently coexists with olfactory problems. Additionally, some participants without a confirmed history of infection may have been misclassified, highlighting a need for contextual caution in interpreting data related to COVID-19's broader impacts on health.

This research underscores the need for greater awareness of ongoing health issues related to COVID-19, such as hyposmia, and highlights the importance of proactive healthcare measures to support recovery. With ongoing evaluations and potential treatment strategies, a clearer understanding of post-COVID health trajectories may emerge, ultimately guiding better outcomes for individuals affected by this pervasive virus.