Related Experiment Video
Updated: May 21, 2025

Author Spotlight: Assessing the Olfactory Effects of Airborne Pollutants — Buried Food and Social Odor Tests
Published on: September 13, 2024
Unmasking Risk Factors for Post-COVID-19 Olfactory Dysfunction Resulting From Early Stages of the Pandemic: A
Brooke Stephanian1,2, Jacob Hoerter1, Julia Wei3
1Department of Otolaryngology-Head & Neck Surgery, Kaiser Permanente Oakland Medical Center, Oakland, CA, USA.
Introduction:
The COVID-19 pandemic has highlighted olfactory dysfunction (OD) as a major and often persistent symptom in affected individuals. Thus, it is important to identify demographic and clinical factors contributing to OD among patients with COVID-19.
Methods:
A case-control (1:3) study was performed in adult patients with COVID-19 diagnosis between July 2020 and June 2021. Cases had OD; controls did not have OD. OD was subclassified as acute smell loss (< 3 months), chronic smell loss (> 3 months), or altered sense of smell (eg, parosmia, phantosmia). Bivariate tests and multivariable logistic regression were performed for analysis.
Results:
Of the 4220 patients that met criteria, 1055 (25%) had OD. Of those with OD, 650 (61.6%) had acute smell reduction, 350 (33.2%) had chronic smell reduction, and 245 (23.2%) had altered sense of smell. Older (odds ratio [OR], 0.84; 95% confidence interval [CI], 0.79-0.89), male (OR, 0.62; 95% CI, 0.54-0.72), and Asian (OR 0.75; 95% CI, 0.59-0.95) patients were less likely to experience OD. Having seasonal allergies (OR, 1.44; 95% CI, 1.11-1.86) and being hospitalized (OR, 1.52; 95% CI, 1.14-2.02) increased the likelihood of OD development. Compared with acute loss, chronic smell loss was likelier in older, female, non-White, hospitalized, and cerebrovascular disease patients (P < .05).
Discussion:
Understanding the course of post-COVID-19 OD is becoming increasingly important and may broaden these insights.
Conclusion:
Being younger, female, and atopic conferred highest likelihood of OD development after COVID-19.
Related Concept Videos
Pneumonia II: Pathophysiology
Pneumonia I: Introduction
Risk Factors
Various factors influence the likelihood of developing pneumonia. Age plays a crucial role, with infants, children under two, and individuals over 65 at increased risk due to their...
Olfaction
The olfactory receptors are embedded in the cilia of the...
Chronic Obstructive Pulmonary Disease
Smoking is a primary risk factor for COPD, with over 80% of patients having a history of it. Patients typically experience progressive dyspnea or labored breathing, frequent coughing, and recurrent pulmonary infections. Many eventually succumb to respiratory failure, characterized by...
Chronic Obstructive Pulmonary Disease-I: Introduction
Chronic Obstructive Pulmonary Disease-III: Symptoms and Complications.
Symptoms of COPD can be classified as primary or systemic. Primary symptoms relate to reduced airflow, while systemic or extrapulmonary symptoms relate to COPD's broader impact on the body.
Primary Symptoms of COPD:

