Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2021;83(4):209-218.
doi: 10.1159/000515132. Epub 2021 Mar 31.

Sustained Chemosensory Dysfunction during the COVID-19 Pandemic

Janne Schwab  1   2 , Caroline Damsgaard Jensen  1   2 , Alexander Wieck Fjaeldstad  1   2   3
Affiliations

Sustained Chemosensory Dysfunction during the COVID-19 Pandemic

Janne Schwab et al. ORL J Otorhinolaryngol Relat Spec. 2021.

Abstract

Introduction: Chemosensory dysfunction (CD) has proven valuable in prediction of COVID-19, as it is a frequent and specific symptom of the disease. The aim of this study was to investigate the duration of CD in patients with sudden subjective olfactory and/or gustatory loss during the SARS-CoV-2 pandemic. The secondary aim was to identify possible prognostic factors for the duration of CD.

Methods: An online baseline questionnaire was designed to assess subjective CD. Three rounds of follow-up questionnaires were sent out to any participants with persistent CD in 6-week intervals, prospectively assessing subjective chemosensory function and extending the follow-up time of this cohort significantly.

Results: In total, 467 participants completed the baseline questionnaire. The most significant improvement and recovery of chemosensory function was observed within the first month after the initial loss. Rates became stagnant after about 2 months, and only little improvement and recovery was seen after 2-4 months. After a mean follow-up of 95.9 days (olfactory dysfunction) and 94.0 days (gustatory dysfunction), 86.7% of participants reported gustatory improvement and 82.6% reported olfactory improvement, while 55.0% reported full gustatory recovery and 43.8% reported full olfactory recovery. Female gender was associated with better improvement of gustatory function. High subjective severity of chemosensory loss was associated with lower rates of olfactory and gustatory recovery as well as improvement of olfactory function. Young age was not associated with a better prognosis.

Discussion/conclusion: Rates of improvement and recovery of chemosensory function decreased after 2-4 months after initial chemosensory loss, possibly indicating that prolonged and perhaps permanent chemosensory loss may be a complication of SARS-CoV-2 infections. High subjective severity of CD may worsen the prognosis for improvement and recovery of chemosensory function.

Keywords: COVID-19; Chemosensory loss; Prognosis; Smell; Taste.

PubMed Disclaimer

Conflict of interest statement

The authors have no financial disclosures or conflicts of interest.

Figures

Fig. 1
Fig. 1
Flowchart for chemosensory recovery and improvement in follow-up questionnaires. *Among the 236 participants who had not achieved complete sensory recovery, 64 participants had not replied to any of the follow-up questionnaires.
Fig. 2
Fig. 2
Chemosensory improvement and recovery during the initial 4 months. Note that complete improvement/recovery (y-axis) is based on the initial chemosensory loss in the baseline questionnaire. In total, 25/467 participants did not choose to add email addresses for further follow-up and 64 participants did not reply to any of the follow-up questionnaires. As such, the longer duration estimates are based on the 203 participants who filled out one or more follow-up questionnaires. Although the rates of improvement/recovery may be underestimated after day 65 (duration of chemosensory loss in baseline questionnaire), there seems to be a decrease in recovery rates for both senses after 1–2 months. To ensure sufficient data for the graph, the follow-up time displayed was restricted to the mean follow-up time of the follow-up questionnaire participants (128 days).
Fig. 3
Fig. 3
Distribution of age and recovery. a Age distribution of participants with olfactory dysfunction (full color) and recovery (gray stripes) distribution. b Age distribution of participants with gustatory dysfunction (full color) and recovery (gray stripes) distribution.
See this image and copyright information in PMC

References

    1. van Doremalen N, Bushmaker T, Morris DH, Holbrook MG, Gamble A, Williamson BN, et al. Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1. N Engl J Med. 2020 Apr 16;382((16)):1564–7. - PMC - PubMed
    1. World Health Organisation Coronavirus disease (COVID-19) 2020. [cited 2020 Oct 30] Available from: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/question....
    1. Menni C, Valdes AM, Freidin MB, Sudre CH, Nguyen LH, Drew DA, et al. Real-time tracking of self-reported symptoms to predict potential COVID-19. Nat Med. 2020 Jul;26((7)):1037–40. - PMC - PubMed
    1. Wagner T, Shweta F, Murugadoss K, Awasthi S, Venkatakrishnan A, Bade S, et al. Augmented curation of clinical notes from a massive EHR system reveals symptoms of impending COVID-19 diagnosis. Elife. 2020 Jul 7;9:e58277. - PMC - PubMed
    1. Agyeman AA, Chin KL, Landersdorfer CB, Liew D, Ofori-Asenso R. Smell and taste dysfunction in patients with COVID-19: a systematic review and meta-analysis. Mayo Clin Proc. 2020 Aug;95((8)):1621–31. - PMC - PubMed