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NCT Number: NCT04366934

Study of the Pathogenesis of Olfactory Disorders in COVID-19

This study is a case-control study to characterize the molecular and cellular anomalies of the olfactory epithelium of COVID-19 patients with isolated anosmia, by comparison with the olfactory epithelium of non-infected subjects.

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Key information

Conditions

Coronavirus Infection Anosmia Coronaviridae Infections Coronavirus Infections Infections Nervous System Diseases Neurologic Manifestations Nidovirales Infections Olfaction Disorders Pathological Conditions, Signs and Symptoms RNA Virus Infections Respiratory Tract Diseases Respiratory Tract Infections Sars-CoV2 Sensation Disorders Severe Acute Respiratory Syndrome Signs and Symptoms Virus Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Hôpital Lariboisière, Policlinique, Paris, France

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About this study

Olfactory and taste dysfunctions are common and early onset in COVID-19, especially in pauci symptomatic patients, and may be the main clinical manifestations of the infection. Olfactory dysfunction could result from infection of the olfactory system by SARS-CoV-2 or from inflammation induced by the virus. While the recent development of COVID-19 pulmonary lesion research has revealed a viral, inflammatory and vascular origin, factors that cause olfactory disorders in COVID-19 are just beginning.

Acute anosmia observed in some patients with COVID-19 could result from:

  • the direct infection of olfactory sensory neurons or neural stem cells of the olfactory mucosa,
  • an underlying inflammation of the olfactory mucosa, leading to possible neurodegeneration of olfactory sensory neurons, and neural stem cells of the olfactory mucosa, by analogy with the respiratory viruses responsible for chronic rhinosinusitis.

It is therefore necessary to conduct a virological, cellular, immunological and inflammatory study of the olfactory epithelium from COVID-19 patients with isolated anosmia to identify the origin of these olfactory disorders.

This study is a case-control study to characterize the molecular and cellular anomalies of the olfactory epithelium of COVID-19 patients with isolated anosmia, by comparison with the olfactory epithelium of non-infected subjects.

Following measures will be performed at inclusion :

  • Taste and olfactory function evaluation by a self-questionnaire taste and smell survey (TTS) and a visual analogue scale (VAS)
  • Nasal swab sampling for collection of epithelium cells and olfactory mucus.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

COVID-19 patients

  • Age > 18 years
  • Subject consulting in the context of the COVID-19 screening care for a suspected SARS-CoV-2 infection

Controls

  • Age > 18 years
  • Subject consulting in the ear, nose and throat department with no biologically confirmed COVID-19 or suspected COVID-19 in the past 8 weeks, and no symptoms suggestive of COVID-19 or another respiratory disease and therefore no recent anosmia or ageusia

Exclusion criteria

(both COVID-19 patients and controls):

  • Refusal or contraindication to nasal swab
  • Presence of nasal sinus pathology

Treatment and study plan

Nasal Swab

Other

Nasal swab

Taste and olfactory function evaluation

Other

Taste and olfactory function evaluation

Primary outcomes

  1. Molecular and cellular defects in olfactory epithelium

    Time frame: 30 months

    Ratio of olfactory sensory cells in the nasal cytological sample

Secondary outcomes

  1. Biological mechanisms involved in the pathogenesis of the disease

    Time frame: 30 months

    Multiple measurements will be analyzed to characterize the immune and inflamatory status of the olfactory mucosa (presence of infiltrated immune cells, activation state of the immune cells in the epithelium, cytokine and interleukin level)

  2. Epidemiological characteristics

    Time frame: 30 months

    Demographic variables (sex, age, blood type), risk factors (tobacco, overweight, diabetes, rhinosinusitis disease, respiratory allergy)

  3. Olfactory and taste dysfunction

    Time frame: 30 months

    Self-questionnaire taste and smell survey (TTS)

  4. Olfactory and taste dysfunction

    Time frame: 30 months

    Visual analogue scale (VAS) (units from 0 normal perception to 100 no perception)

Sponsors and collaborators

Lead sponsor

Institut Pasteur

Industry

Collaborators

  • Hopital Lariboisière

Registry information

Acronym: COVIDSMELL

Important dates

Study start
2020
Primary completion
2020
Study completion
2020
First posted
Apr 29, 2020
Registry last updated
Sep 22, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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