Olfactory dysfunction after SARS-CoV-2 infection in the RECOVER adult cohort
Horwitz, LI; Becker, JH; Huang, W; et al., JAMA Network Open
Published
September 2025
Journal
JAMA Network Open
Abstract
Importance: Olfactory dysfunction is common after SARS-CoV-2 infection and has been associated with cognitive loss in other conditions. Formal testing is needed to characterize the presence, severity, and patterns of olfactory dysfunction.
Objective: To characterize long-term olfactory dysfunction after SARS-CoV-2 infection.
Design, setting, and participants: This prospective cohort study included adults enrolled in the Researching COVID to Enhance Recovery (RECOVER)-Adult study. All those with and a random sample of those without self-reported change or loss in smell or taste were offered olfactory testing, performed at 83 sites in 35 US states and territories. Participants included 2,956 enrollees with prior infection (1,393 with and 1,563 without self-reported change or loss) and 569 without prior infection (9 with and 560 without self-reported change or loss in taste) who underwent olfactory testing a mean (SD) of 671.6 (417.8) days after the index date. Data were collected from October 29, 2021, to June 6, 2025.
Exposure: SARS-CoV-2 infection.
Main outcomes and measures: Olfactory function, as defined by age- and sex-standardized performance on the University of Pennsylvania Smell Identification Test (UPSIT), a well-validated test comprising 40 unique odors.
Results: The study included 3,525 participants with a mean (SD) age of 47.6 (15.2) years; of 3,520 with data available, 2,548 (72.4%) were female or intersex. Among 1,393 infected participants with self-reported change or loss, 1,111 (79.8%) had hyposmia on the UPSIT, including 321 (23.0%) with severe microsmia or anosmia. Among 1,563 infected participants without self-reported change or loss, 1,031 (66.0%) had hyposmia, including 128 (8.2%) with severe microsmia or anosmia. Participants with prior infection and self-reported change or loss scored at the 16th age- and sex-standardized UPSIT percentile, compared with the 23rd and 28th percentiles for those without self-reported change or loss with and without prior known infection, respectively. Younger women had scores corresponding to lower mean age- and sex-standardized percentiles. Among participants who self-reported change or loss in smell, those with abnormal UPSIT scores more often reported cognitive problems (742 of 1,111 [66.8%]) than those with normal UPSIT scores (179 of 282 [63.5%]).
Conclusions and relevance: In this cohort study of RECOVER-Adult participants, self-reported change or loss in smell or taste was an accurate signal of verified hyposmia, but a high rate of hyposmia among those with no reported change or loss was also observed. Formal smell testing may be considered in those with prior SARS-CoV-2 infection to diagnose occult hyposmia and counsel patients about risks.
Authors
Leora I Horwitz, Jacqueline H Becker, Weixing Huang, Teresa Akintonwa, Maxwell M Hornig-Rohan, Gabrielle Maranga, Dara R Adams, Mark W Albers, Mirna Ayache, Jasmine Berry, Hassan Brim, Tanner W Bryan, Alexander W Charney, Robert A Clark, Melissa M Cortez, Brian D’Anza, Hannah Davis, Sarah E Donohue, Nathaniel Erdmann, Valerie Flaherman, Tamara G Fong, Jennifer A Frontera, Mark P Goldberg, Jason D Goldman, Michelle S Harkins, Sally L Hodder, Vanessa L Jacoby, Prasanna Jagannathan, Xiaolin Jia, John Daniel Kelly, Jerry A Krishnan, Andre Kumar, Adeyinka O Laiyemo, Emily B Levitan, Jeffrey N Martin, Kathryn M McCaffrey, Grace A McComsey, Torri D Metz, Ganesh Murthy, Helen Nguyen, Megumi Okumura, Samuel Parry, Sairam Parthasarathy, Thomas F Patterson, Michael J Peluso, Christina Sorochinsky, Tiffany Walker, Samantha L Wiegand, Zanthia Wiley, Juan Wisnivesky, Hassan Ashktorab, Andrea Foulkes, Joyce K Lee-Iannotti, RECOVER Consortium
Keywords
Humans; Female; COVID-19/complications; Male; Olfaction Disorders/epidemiology/etiology/virology/diagnosis; Middle Aged; Adult; Prospective Studies; SARS-CoV-2; Aged; United States/epidemiology; Smell
Short Summary
This RECOVER study looked at how sense of smell changed over time in people who had COVID-19. Researchers gave a “scratch-and-sniff” test to a large group of people about 2 years after they had COVID-19. This test, called the University of Pennsylvania Identification Test (UPSIT), checks whether people can smell certain odors. The study found that 8 out of 10 people who felt that they had lost or had changes in smell after having COVID-19 were in fact not able to smell the odors normally. Even two-thirds of the people who thought their sense of smell was completely normal had a weaker sense of smell than they realized. These findings show that a weaker sense of smell can be a common and lasting problem after COVID-19. Because changes in smell have been linked to memory and thinking problems in other conditions, this could mean that people with changes in smell from COVID-19 could be at risk for thinking and memory issues. Doctors should use special smell tests to point out smell loss that patients may not notice to help them understand their condition and its risks, like not being able to smell smoke or spoiled food.