Coronavirus InfectionCOVIDSMELLNCT04366934
Study of the Pathogenesis of Olfactory Disorders in COVID-19
An observational study of Coronavirus Infection and Severe Acute Respiratory Syndrome, run by Institut Pasteur at 2 sites in France.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Coronavirus Infection, Severe Acute Respiratory Syndrome, Sars-CoV2
- What is being tested?
- Nasal swab and Taste and olfactory function evaluation
- How many people
- 26 participants
- Where
- 2 sitesFrance
- Study dates
- 4 May 2020to 29 Oct 2020
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: COVID-19 patients and control subjects
Who may be able to join
- 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
Who cannot join
- Refusal or contraindication to nasal swab
- Presence of nasal sinus pathology
Trial locations and contacts
2 sites in 1 country.
France2 sites
Hôpital Lariboisière, Policlinique
Paris
Hôpital Lariboisière, Service ORL
Paris
About this study
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.
Read the detailed description
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.
- Being tested
- Nasal swab, Taste and olfactory function evaluation
- Keywords
- SARS-CoV-2, Sense of smell disorders, Anosmia, Olfaction, Nasal neuroepithelium, Olfactory mucosa
- Medical subject headings
- Coronavirus Infections, Severe Acute Respiratory Syndrome, Anosmia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Nasal swabOther
Nasal swab
Taste and olfactory function evaluationOther
Taste and olfactory function evaluation
| Study group | Role | What they receive |
|---|---|---|
| COVID-19 patients | Subject consulting in the Lariboisière hospital (Paris) in the context of the COVID-19 screening care for a suspected SARS-CoV-2 infection Receives: Other: Nasal swab; Other: Taste and olfactory function evaluation | |
| Control subjects | Subject consulting in the ear, nose and throat department at the Lariboisière hospital (Paris) 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 Receives: Other: Nasal swab; Other: Taste and olfactory function evaluation |
What is being measured
The primary outcome is the main question the study is designed to answer.
Molecular and cellular defects in olfactory epithelium
Ratio of olfactory sensory cells in the nasal cytological sample
Measured: 30 months
Secondary outcomes (4)
Biological mechanisms involved in the pathogenesis of the disease
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)
Measured: 30 months
Epidemiological characteristics
Demographic variables (sex, age, blood type), risk factors (tobacco, overweight, diabetes, rhinosinusitis disease, respiratory allergy)
Measured: 30 months
Olfactory and taste dysfunction
Self-questionnaire taste and smell survey (TTS)
Measured: 30 months
Olfactory and taste dysfunction
Visual analogue scale (VAS) (units from 0 normal perception to 100 no perception)
Measured: 30 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted29 Apr 2020
- Study start4 May 2020
- Primary completion29 Oct 2020
- Study completion29 Oct 2020
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Coronavirus InfectionStudies of the same condition, open and under way.
- More trials run by Institut PasteurThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case-control
- Time perspective
- Cross-sectional
- Enrolment
- 26 participants (actual)
Sponsor and investigators
- Lead sponsor
- Institut Pasteur
- Sponsor type
- Industry (pharma, biotech, devices)
- Collaborators
- Hopital Lariboisière
- Responsible party
- Sponsor
- Investigators
- Françoise LAZARINI, PhD, Study director, Institut Pasteur
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04366934
- Sponsor's protocol ID
- 2020-021
- Acronym
- COVIDSMELL
- Status last verified
- Sep 2025
- First submitted
- 22 Apr 2020
- Last updated
- 22 Sep 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
de Melo GD, Lazarini F, Levallois S, Hautefort C, Michel V, Larrous F, Verillaud B, Aparicio C, Wagner S, Gheusi G, Kergoat L, Kornobis E, Donati F, Cokelaer T, Hervochon R, Madec Y, Roze E, Salmon D, Bourhy H, Lecuit M, Lledo PM. COVID-19-related anosmia is associated with viral persistence and inflammation in human olfactory epithelium and brain infection in hamsters. Sci Transl Med. 2021 Jun 2;13(596):eabf8396. doi: 10.1126/scitranslmed.abf8396. Epub 2021 May 3.
PubMed 33941622
Study at a glance
From the registry record, last updated by the sponsor on 22 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Study of the Pathogenesis of Olfactory Disorders in COVID-19
- ClinicalTrials.gov ID
- NCT04366934
- Acronym / sponsor ID
- COVIDSMELL / 2020-021
- Keywords
- SARS-CoV-2, Sense of smell disorders, Anosmia, Olfaction, Nasal neuroepithelium, Olfactory mucosa
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 26 participants (actual)
- Lead sponsor
- Institut PasteurIndustry (pharma, biotech, devices)
- Collaborators
- Hopital Lariboisière
- Study start
- 4 May 2020 (actual)
- Primary completion
- 29 Oct 2020 (actual)
- Study completion
- 29 Oct 2020 (actual)
- First posted
- 29 Apr 2020 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
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.
Study design
- Observational model
- Case-control
- Time perspective
- Cross-sectional
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| COVID-19 patients | – | Other: Nasal swab, Other: Taste and olfactory function evaluationSubject consulting in the Lariboisière hospital (Paris) in the context of the COVID-19 screening care for a suspected SARS-CoV-2 infection |
| Control subjects | – | Other: Nasal swab, Other: Taste and olfactory function evaluationSubject consulting in the ear, nose and throat department at the Lariboisière hospital (Paris) 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 |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- COVID-19 patients and control subjects
Key inclusion criteria (6 listed)
- 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
Key exclusion criteria (2 listed)
- Refusal or contraindication to nasal swab
- Presence of nasal sinus pathology
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Nasal swabNasal swab | Other | COVID-19 patients, Control subjects |
| Taste and olfactory function evaluationTaste and olfactory function evaluation | Other | COVID-19 patients, Control subjects |
Primary outcome
Molecular and cellular defects in olfactory epithelium
Time frame: 30 months
Ratio of olfactory sensory cells in the nasal cytological sample
4 secondary outcomes
Biological mechanisms involved in the pathogenesis of the disease
Time frame: 30 months
Epidemiological characteristics
Time frame: 30 months
Olfactory and taste dysfunction
Time frame: 30 months
Olfactory and taste dysfunction
Time frame: 30 months
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 22 Sep 2025.
- Results publication: PubMed 33941622de Melo GD, Lazarini F, Levallois S, Hautefort C, Michel V, Larrous F, Verillaud B, Aparicio C, Wagner S, Gheusi G, Kergoat L, Kornobis E, Donati F, Cokelaer T, Hervochon R, Madec Y, Roze E, Salmon D, Bourhy H, Lecuit M, Lledo PM. COVID-19-related anosmia is associated with viral persistence and inflammation in human olfactory epithelium and brain infection in hamsters. Sci Transl Med. 2021 Jun 2;13(596):eabf8396. doi: 10.1126/scitranslmed.abf8396. Epub 2021 May 3.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Françoise LAZARINI, PhD study director
Institut Pasteur
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Coronavirus Infection and Severe Acute Respiratory Syndrome, run by Institut Pasteur at 2 sites in France.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 22 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in France. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Molecular and cellular defects in olfactory epithelium (time frame: 30 months). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT04366934, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 22 Sep 2025.