Investigating olfactory dysfunction after COVID-19 infection

Dysfunction of Olfaction After SARS-CoV-2 Infection: Morphological and Histomolecular Investigation of Olfactory Cleft Biopsies and Cytobrushes

NA · Universitaire Ziekenhuizen KU Leuven · NCT06482138

This study is trying to understand why some people still have trouble smelling after recovering from COVID-19 by looking at samples from their noses.

Quick facts

PhaseNA
Study typeInterventional
Enrollment240 (estimated)
Ages18 Years to 70 Years
SexAll
SponsorUniversitaire Ziekenhuizen KU Leuven (other)
Locations7 sites (Brussels, Brussels Capital and 6 other locations)
Trial IDNCT06482138 on ClinicalTrials.gov

What this trial studies

This study explores the mechanisms behind persistent olfactory dysfunction in patients who have recovered from COVID-19. It involves collecting biopsies and cytobrush samples from the olfactory cleft of patients with and without olfactory dysfunction. The samples will be analyzed using advanced techniques such as single cell RNA sequencing and immunohistochemistry to understand the underlying biological changes. Patients will be evaluated by ENT specialists as part of their standard care.

Who should consider this trial

Good fit: Ideal candidates include individuals who have experienced olfactory dysfunction following COVID-19, as well as those who have not experienced any olfactory issues.

Not a fit: Patients with other nasal mucosal pathologies or those on anticoagulation therapy may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could lead to better understanding and treatment options for patients suffering from olfactory dysfunction after COVID-19.

How similar studies have performed: While there have been studies on olfactory dysfunction, this specific investigation into post-COVID-19 olfactory dysfunction using advanced molecular techniques is relatively novel.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Olfactory Dysfunction group: Presence of evident OD (Parosmia, Threshold-Discrimination-Identification (TDI)-score ≤24, Subjective abnormal quantitative olfactory function; measured by a visual analogue score (VAS) of smell impairment ≥5/10
* Control group: No OD (TDI-score \>30.5.)

Exclusion Criteria:

* Presence of concomitant nasal mucosal pathology that might affect olfactory function or bias the study investigations
* Use of anticoagulation therapy
* Allergy to local anesthetics

Where this trial is running

Brussels, Brussels Capital and 6 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Covid19, Olfactory Dysfunction, COVID-19, SARS-CoV-2, Anosmia, Hyposmia

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.