Study: Over 20 Million US COVID Patients Suffered Long-term Loss of Smell and Taste

Mass Eye and Ear researchers conducted a study estimating that more than 20 million American patients who had COVID-19 in 2021 lost their sense of taste or smell, with a significant number never completely regaining these senses. The research also established a connection between the intensity of COVID-19 symptoms and the probability of sensory recovery.

Analysts from Mass Eye and Ear led a review of nationwide data, concluding that over 20 million patients suffering from COVID in 2021 experienced loss of smell or taste, with a substantial percentage failing to fully regain these senses.

Throughout the COVID-19 pandemic, many patients reported a loss of taste and smell during and following their SARS-CoV-2 infection. A retrospective study by Massachusetts Eye and Ear, a member of the Mass General Brigham healthcare system, explored the loss of these senses and estimated that about one-fourth of American COVID-19 patients reported only partial or no recovery of taste or smell. These findings are now published in The Laryngoscope.

Neil Bhattacharyya, MD, FACS, Professor of Otolaryngology at Mass Eye and Ear, said, “We aimed to quantify the national effect of smell disorders resulting from COVID. This data helps us understand how many individuals lost their sense of smell or taste due to COVID infection and how many never fully regained these senses.”

The study used data from the 2021 National Health Interview Survey (NHIS), a division of the Centers for Disease Control (CDC), which collected data from 29,696 adults. In the NHIS data, patients with COVID were questioned about their symptom severity, any loss of taste or smell, and their sensory recovery.

Researchers found that approximately 60 percent of surveyed participants infected with COVID suffered a loss of smell and about 58 percent lost their sense of taste. Moreover, not all patients regained their senses completely after recovering from the infection.

The study revealed that roughly 72 percent of patients fully recovered their sense of smell, while 24 percent partially regained it, and over 3 percent did not recover at all. Similarly, out of those who lost their sense of taste due to COVID, approximately 76 percent fully regained the sense, while 20 percent partially recovered, and over 2 percent did not recover at all. This translates to nearly 28 million Americans potentially left with a reduced sense of smell after their COVID infection.

Bhattacharyya recalled a patient who lost 50 pounds due to his COVID-related loss of smell, saying, “The patient stopped eating and became severely ill and depressed due to the loss of smell. While most people tend to recover from COVID-related smell loss, a substantial number do not.”

The study also discovered a correlation between COVID symptom severity and the loss of smell or taste. As symptoms intensified, the percentage of patients experiencing sensory loss also increased. Furthermore, the chances of smell and taste recovery decreased with more severe COVID symptoms.

The researchers noted that since smell and taste often coincide, patients may find it challenging to self-report which senses have or have not recovered. However, a large population continues to suffer from loss of smell and taste as a COVID aftermath.

The study stands out for its national population sample, but the data only encompasses patients treated in 2021. Therefore, patients before and after 2021 were not included, and if a person regained their sense of smell or taste post-2021, it was not recorded in the data. Furthermore, the study may not accurately reflect the rates of sensory loss due to variants of COVID that emerged after 2021.

While there is no standard treatment currently available for patients suffering from smell and taste deficits, the researchers believe these findings can aid healthcare providers in counseling patients who lost these senses due to COVID and in monitoring recovery rates.

Bhattacharyya emphasized, “The significance of this study lies in spotlighting a group that has been somewhat overlooked. Losing your sense of smell or taste can have serious consequences, including reduced pleasure in eating and, in more severe cases, can lead to depression and weight loss.”

Reference: “Smell and Taste Loss Associated with COVID Infection” by Margaret B. Mitchell MD, MS-HPEd, Alan D. Workman MD, MTR, Vinay K. Rathi MD, MBA and Neil Bhattacharyya MD, FACS, 2 June 2023, The Laryngoscope.
DOI: 10.1002/lary.30802

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More about COVID-19 induced loss of smell and taste

• Mass Eye and Ear
• The Laryngoscope Journal
• National Health Interview Survey
• Mass General Brigham healthcare system