SARS-CoV-2 (COVID-19)Phase 1COVHIC003NCT07397455
Development of a Controlled Human Infection Model for Assessment of SARS-CoV-2 Omicron Subvariants
A Phase 1 study testing SARS-CoV-2 Omicron EG.5.1 challenge agent 10^5 TCID50, SARS-CoV-2 Omicron EG.5.1 challenge agent 10^6 TCID50 and SARS-CoV-2 Omicron EG.5.1 challenge agent 10^4 TCID50 in people with SARS-CoV-2 (COVID-19), run by Imperial College London at 5 sites in United Kingdom.
Trial summary
COVHIC003 is a human infection challenge study in which healthy adults aged 18-50 previously vaccinated with an approved COVID-19 vaccine will be administered a SARS-CoV-2 Omicron EG.5.1 variant given by drops in the nose. Read more about this study
- Who is it for?
- Ages 18 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- SARS-CoV-2 (COVID-19)
- What is being tested?
- SARS-CoV-2 Omicron EG.5.1 challenge agent 10^5 TCID50, SARS-CoV-2 Omicron EG.5.1 challenge agent 10^6 TCID50 and SARS-CoV-2 Omicron EG.5.1 challenge agent 10^4 TCID50
- Type of treatment
- Vaccines
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 38 participants
- Where
- 5 sitesUnited Kingdom
- Study dates
- 10 Jul 2026to 31 Dec 2028
- Phase
- Phase 1
- Are there results?
- Not yet: the study is under way
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 to 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- The study informed consent form has been signed and dated by the participant and the Investigator
- Adults age between 18 and 50 years inclusive (at the time of enrolment)
- Evidence of having had at least one COVID-19 vaccine, with the last vaccination at least 3 months before enrolment
- Positive serology for SARS-CoV-2 at (pre)screening
- Sero-suitable as defined by having serum and/or nasal antibody titres less than a pre-defined cut-off of a defined assay(s) which will be specified in a separate SOP and based on accumulating antibody data
- People of child-bearing potential (POCBP) must be willing and able to use contraception as described in the study protocol from 2 weeks before the scheduled date of viral challenge until the end discharge from quarantine.
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- Negative urine pregnancy tests will be required at screening and on day 0 prior to inoculation. On admission to the quarantine unit a negative serum beta human chorionic gonadotropin (β-hCG) is required
- Male participants who are willing to use one of the contraception methods described in the study protocol, from the time of the date of viral challenge until the end of quarantine
- Agree to abstain from sexual activity or use effective contraception from the start of treatment with Paxlovid until 7 days after completing treatment with Paxlovid should they receive it
- In good health with no history of clinically significant medical conditions (as described in Exclusion criteria) that would interfere with participant safety, as defined by medical history, physical examination and routine laboratory tests, ECG, and Chest X-Ray and determined by the Investigator at an admission evaluation
- Participants will have a documented medical history either prior to entering the study and/or following medical history review with the study physician at screening
- Willing to be registered with The Over-Volunteering Protection Service (TOPS)
- Willing and able to commit to participation in the study.
Who cannot join
- History or evidence of any clinically significant or currently active cardiovascular, (including thromboembolic events), respiratory, dermatological, gastrointestinal, endocrine, haematological, hepatic, immunological, rheumatological, metabolic, urological, renal, neurological, psychiatric illness
- Any significant abnormality altering the anatomy or function of the nose or nasopharynx in a substantial way (including loss of or alterations in smell or taste), a clinically significant history of epistaxis (large nosebleeds) within the last 3 months, nasal or sinus surgery within 6 months of inoculation
- Clinically-active, symptomatic rhinitis (including hay fever) or history of severe rhinitis, or seasonal allergic rhinitis likely to be active at the time of inclusion into the study and/or requiring regular nasal corticosteroids on an at least weekly basis, within 30 days of admission to quarantine
- History of anaphylaxis and/or a history of severe allergic reaction or significant intolerance to any food or drug, as assessed by the Investigator
- Significant history or presence of drug or alcohol misuse (exceeding >28 units a week)
- Current use of any drugs taken through the nasal or inhaled route including recreational drugs
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- Psychiatric illness including participants with a history of depression and/or anxiety with associated severe psychiatric comorbidities, for example psychosis.
- Current active smokers, equivalent to >5 cigarettes per week, including use of tobacco in any form (e.g., smoking or chewing) or other nicotine-containing products in any form (e.g., gum, patch) or electronic cigarettes. • Participants who have smoked ≥5 pack years at any time [5 pack years is equivalent to one pack of 20 cigarettes a day for 5 years]) or the equivalent amount of nicotine if using alternative forms. • Ex-smokers who have smoked <5 pack years at any time must not of have regularly smoked in the last 3 months equivalent to >5 cigarettes per week.
- Family history of 1st degree relative aged 50 years or less with sudden cardiac or unexplained death
- Personal or Family History of unexpectedly severe COVID-19, adverse response to any other viral disease e.g. Guillain-Barré, or a family history (described as a 1st degree relative) with clotting disorders
- A total body weight of ≤ 45kg and a Body Mass Index (BMI) ≤18 kg/m2 and ≥28 kg/m2. The upper limit of BMI may be increased to ≤ 30kg/m2 at the Investigator's discretion, in the case of physically fit muscular individual
- Venous access deemed inadequate for the phlebotomy demands of the study.
- Any clinically significant abnormal finding on screening biochemistry, haematology and microbiology blood tests or urinalysis i.e. grade 1 lab abnormalities or above apart from minor deviations which are clinically acceptable and approved by the Investigator
- A forced expiratory volume in 1 second (FEV1) and a forced vital capacity (FVC) <80% of predicted value calculated using ATS/ERS guidance. Spirometry will be performed only if the mMRC dyspnoea score ≥1 or if clinically indicated
- Twelve-lead ECG recording with clinically relevant abnormalities as judged by the Investigator
- History of, or currently active symptoms suggestive of upper or lower respiratory tract infection (including reduced sense of taste and smell, raised body temperature and/or persistent cough) within 4 weeks prior to viral challenge
- Presence of cold-like symptoms and/or fever (defined as participant presenting with a temperature reading of >37.9ºC) on Day -2, Day -1 and/or pre-challenge on Day 0.
- Evidence of any respiratory pathogens (on Respiratory PCR from upper respiratory tract sample) prior to challenge virus inoculation on admission to the quarantine unit
- Evidence of a live vaccine within 60 days prior to the planned date of viral challenge, a non-live vaccine within 30 days prior to the planned date of viral challenge or intention to receive any vaccination(s) before the day 28 follow-up visit. (NB. No travel restrictions applied after the Day 28 Follow-up visit).
- Receipt of blood or blood products, or loss (including blood donations) of 550 mL or more of blood during the 3 months prior to the planned date of viral challenge or planned during the 3 months after the final visit.
- Medications
- Use of any medication or product (prescription or over-the-counter), for symptoms of hay fever, nasal congestion or respiratory tract infections or dermatitis/eczema including the use of regular nasal or medium-high potency dermal corticosteroids, antibiotics and First Defence™ (or generic equivalents) within 7 days prior to the planned date of viral challenge apart from those described in Table 7, Permitted Medication or agreed by the Investigator.
- Receipt of any investigational drug within 3 months prior to the planned date of viral challenge.
- Receipt of three or more investigational drugs within the previous 12 months prior to the planned date of viral challenge.
- Receipt of systemic (intravenous and/or oral) glucocorticoids or antiviral drugs known to have activity against respiratory viruses within 6 months prior to the planned date of viral challenge (excluding Pre-Exposure Prophylaxis (PrEP)).
- Over the counter medications (e.g., paracetamol or ibuprofen) where the dose taken over the preceding 7 days prior to the planned date of viral challenge had exceeded the maximum permissible 24-hour dose (e.g., >4g per day of paracetamol over the preceding week).
- Chronically used medications, including any medication known to be a moderate/potent inducer or inhibitor of cytochrome P450 enzymes, within 21 days prior to the planned date of viral challenge, except for those agreed by the Investigator.
- Participants who have received any systemic chemotherapy agent, immunoglobulins, or other cytotoxic or immunosuppressive drugs at any time.
- Concurrent use of medications strongly contraindicated for use with Paxlovid unless confirmed alternative rescue therapy will be available to the site at the time of enrolment
- Prior participation in another human viral challenge study in the preceding 6 months taken from the date of viral challenge in the previous study to the date of expected viral challenge in this study. The participant must also have completed the follow up visit requirements of the previous viral challenge study
- Any invasive nasal sampling procedure in the month before date of expected viral challenge in this study (excluding study tolerance test or routine tests for COVID-19)
- Participant is mentally or legally incapacitated in the opinion of the Investigator
- POCBP who:
- Are breastfeeding within 6 months of study commencement, or
- Had been pregnant within 6 months prior to the study, or
- Had a positive pregnancy test at any point during screening or prior to inoculation with challenge virus
- Those in close domestic contact (i.e. sharing a household with, caring for, or daily face to face contact) with children under 2 years, the elderly (>65 years), immunosuppressed persons, or those with chronic respiratory disease
- Anyone who works on the study (e.g. a delegated study nurse) or in close proximity to the study at the sponsor organisation, participating trial sites or any contract research organisations involved in this study.
- Anyone who is first degree related to, or resides with, anyone who is a delegated member of the research team at a study site
- Any other reason that the Investigator considered made the participant unsuitable to participate
- Participants with no knowledge of their family history
Trial locations and contacts
5 sites in 1 country. Contact the study team or a site near you to ask about taking part.
5 sites in 1 country
United Kingdom5 sites, 5 recruiting
- Recruiting
Royal Free London Nhs Foundation Trust
London, NW3 2QG
Douglas Fink, douglas.fink@nhs.net
Douglas Fink
- Recruiting
Guy's and St Thomas' NHS Foundation Trust
London, SE1 7EH
Anna Goodman, anna.goodman@nhs.net
Anna Goodman
- Recruiting
Imperial College Healthcare NHS Trust
London, W12 0HS
Christopher Chiu, c.chiu@imperial.ac.uk
Polly Fox-Sheehan, polly.fox@imperial.ac.uk
- Not yet recruiting
University of Oxford
Oxford, OX3 7LE
Helen McShane, helen.mcshane@ndm.ox.ac.uk
Helen McShane
- Not yet recruiting
University Hospital Southampton Nhs Foundation Trust
Southampton, S016 6YD
Saul Faust, s.faust@soton.ac.uk
Saul Faust
About this study
COVHIC003 is a human infection challenge study in which healthy adults aged 18-50 previously vaccinated with an approved COVID-19 vaccine will be administered a SARS-CoV-2 Omicron EG.5.1 variant given by drops in the nose. The aim is to achieve breakthrough upper-respiratory infection in a proportion of volunteers with mild or no illness, providing information on the course of Omicron infection and the immune response in vaccinated people. This study will establish an optimised challenge dose and model that can then be used to evaluate new vaccines and treatments in follow-on trials. Participants will stay in a quarantine unit for approximately 10-12 days, depending on infection status, and will be closely monitored with regular swabs, blood tests and symptom assessments throughout their stay. They will be followed up by the study team for 6 months after being discharged. This study is sponsored by Imperial College London and forms part of the MUSICC project which is led by Imperial College London and co-funded by the European Union's Horizon Europe Programme and the Coalition for Epidemic Preparedness Innovations (CEPI). Quarantine will take place at specialist facilities in Oxford or at the Royal Free Hospital in London.
- Conditions
- SARS-CoV-2 (COVID-19)
- Being tested
- SARS-CoV-2 Omicron EG.5.1 challenge agent 10^5 TCID50, SARS-CoV-2 Omicron EG.5.1 challenge agent 10^6 TCID50, SARS-CoV-2 Omicron EG.5.1 challenge agent 10^4 TCID50
- Medical subject headings
- COVID-19
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
SARS-CoV-2 Omicron EG.5.1 challenge agent 10^5 TCID50Biological
10^5 TCID50
This is a SARS-CoV-2 Omicron EG.5.1 challenge agent which has not been given in controlled human infection studies previously.
SARS-CoV-2 Omicron EG.5.1 challenge agent 10^6 TCID50Biological
10^6 TCID50 This is a SARS-CoV-2 Omicron EG.5.1 challenge agent which has not been given in controlled human infection studies previously
SARS-CoV-2 Omicron EG.5.1 challenge agent 10^4 TCID50Biological
10^4 TCID50
This is a SARS-CoV-2 Omicron EG.5.1 challenge agent which has not been given in controlled human infection studies previously
| Study group | Role | What they receive |
|---|---|---|
| Group 1a: SARS-CoV-2 Omicron EG.5.1 | Experimental | Starting dose 10^5 TCID50, vaccinated, pre-selection for low serum antibodies, n = up to 12 Receives: Biological: SARS-CoV-2 Omicron EG.5.1 challenge agent 10^5 TCID50 |
| Group 1b: SARS-CoV-2 Omicron EG.5.1 | Experimental | Dose escalate: 10^6 TCID50, vaccinated, pre-selection for low serum antibodies, n = up to 12 Receives: Biological: SARS-CoV-2 Omicron EG.5.1 challenge agent 10^6 TCID50 |
| Group 1c: SARS-CoV-2 Omicron EG.5.1 | Experimental | Dose de-escalate: 10^4 TCID50, vaccinated, pre-selection for low serum antibodies, n = up to 12 Receives: Biological: SARS-CoV-2 Omicron EG.5.1 challenge agent 10^4 TCID50 |
| Group 2: SARS-CoV-2 Omicron EG.5.1 | Experimental | 10^6 TCID50 with multiple doses and/or lower sero-screening threshold Receives: Biological: SARS-CoV-2 Omicron EG.5.1 challenge agent 10^6 TCID50 |
What is being measured
The primary outcome is the main question the study is designed to answer.
To assess the safety and human clinical response to intranasal challenge of SARS-CoV-2 EG.5.1 variant in healthy participants who are immunologically experienced against SARS-CoV-2.
To evaluate the safety of Omicron variant SARS-CoV-2 challenge in healthy participants, by assessing:
- Occurrence of AEs within 28 days post-viral challenge (Day 0 to Day 28)
Measured: 28 Days
To assess the safety and human clinical response to intranasal challenge of SARS-CoV-2 EG.5.1 variant in healthy participants who are immunologically experienced against SARS-CoV-2.
To evaluate the safety of Omicron variant SARS-CoV-2 challenge in healthy participants, by assessing:
- • Occurrence of SAEs related to the viral challenge (Day 0 to Day 180)
Measured: 180 Days
Selection of the SARS-CoV-2 Omicron EG.5.1 dose(s) required to induce laboratory confirmed upper respiratory tract infection in 50-70% of immunologically experienced, healthy participants following intranasal challenge
Laboratory confirmed infection is defined as: two quantifiable (≥LLOQ) RT-PCR measurements from mid turbinate or throat samples, reported on 2 or more consecutive timepoints, starting from Day 2 (inclusive) post-inoculation and up to discharge from quarantine (Day 8 for uninfected participants or Day 10 for infected participants)
Measured: 10 Days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted9 Feb 2026
- Study start10 Jul 2026
- Primary completion31 Dec 2027 (estimated)
- Study completion31 Dec 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for SARS-CoV-2 (COVID-19)Studies of the same condition, open and under way.
- More trials run by Imperial College LondonThe 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
- Interventional
- Phase
- Phase 1
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Sequential
- Model description
- Dose Escalation/Expansion design
- Masking
- None (open label)
- Enrolment
- 38 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Imperial College London
- Sponsor type
- University, hospital or other
- Collaborators
- Imperial College Healthcare NHS Trust, University College, London, University of Oxford, Royal Free Hospital NHS Foundation Trust, Guy's and St Thomas' NHS Foundation Trust, University Hospital Southampton NHS Foundation Trust, Oxford University Hospitals NHS Trust
- Responsible party
- Sponsor
- Investigators
- Christopher Chiu, BMBCh FRCP FRCPath PhD, Principal investigator, Imperial College London
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07397455
- Sponsor's protocol ID
- 172082
- Acronym
- COVHIC003
- Status last verified
- Jul 2026
- First submitted
- 28 Jan 2026
- Last updated
- 17 Jul 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 17 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Development of a Controlled Human Infection Model for Assessment of SARS-CoV-2 Omicron Subvariants
- ClinicalTrials.gov ID
- NCT07397455
- Acronym / sponsor ID
- COVHIC003 / 172082
- Conditions
- SARS-CoV-2 (COVID-19)
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 38 participants (estimated)
- Lead sponsor
- Imperial College LondonUniversity, hospital or other
- Collaborators
- Imperial College Healthcare NHS Trust, University College, London, University of Oxford, Royal Free Hospital NHS Foundation Trust, Guy's and St Thomas' NHS Foundation Trust, University Hospital Southampton NHS Foundation Trust, Oxford University Hospitals NHS Trust
- Study start
- 10 Jul 2026 (actual)
- Primary completion
- 31 Dec 2027 (estimated)
- Study completion
- 31 Dec 2028 (estimated)
- First posted
- 9 Feb 2026 (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.
COVHIC003 is a human infection challenge study in which healthy adults aged 18-50 previously vaccinated with an approved COVID-19 vaccine will be administered a SARS-CoV-2 Omicron EG.5.1 variant given by drops in the nose. The aim is to achieve breakthrough upper-respiratory infection in a proportion of volunteers with mild or no illness, providing information on the course of Omicron infection and the immune response in vaccinated people. This study will establish an optimised challenge dose and model that can then be used to evaluate new vaccines and treatments in follow-on trials. Participants will stay in a quarantine unit for approximately 10-12 days, depending on infection status, and will be closely monitored with regular swabs, blood tests and symptom assessments throughout their stay. They will be followed up by the study team for 6 months after being discharged. This study is sponsored by Imperial College London and forms part of the MUSICC project which is led by Imperial College London and co-funded by the European Union's Horizon Europe Programme and the Coalition for Epidemic Preparedness Innovations (CEPI). Quarantine will take place at specialist facilities in Oxford or at the Royal Free Hospital in London.
Study design
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Sequential
- Masking
- None (open label)
- Number of arms
- 4
- Model description
- Dose Escalation/Expansion design
| Arm | Type | Receives |
|---|---|---|
| Group 1a: SARS-CoV-2 Omicron EG.5.1 | Experimental | Biological: SARS-CoV-2 Omicron EG.5.1 challenge agent 10^5 TCID50Starting dose 10^5 TCID50, vaccinated, pre-selection for low serum antibodies, n = up to 12 |
| Group 1b: SARS-CoV-2 Omicron EG.5.1 | Experimental | Biological: SARS-CoV-2 Omicron EG.5.1 challenge agent 10^6 TCID50Dose escalate: 10^6 TCID50, vaccinated, pre-selection for low serum antibodies, n = up to 12 |
| Group 1c: SARS-CoV-2 Omicron EG.5.1 | Experimental | Biological: SARS-CoV-2 Omicron EG.5.1 challenge agent 10^4 TCID50Dose de-escalate: 10^4 TCID50, vaccinated, pre-selection for low serum antibodies, n = up to 12 |
| Group 2: SARS-CoV-2 Omicron EG.5.1 | Experimental | Biological: SARS-CoV-2 Omicron EG.5.1 challenge agent 10^6 TCID5010^6 TCID50 with multiple doses and/or lower sero-screening threshold |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (13 listed)
- The study informed consent form has been signed and dated by the participant and the Investigator
- Adults age between 18 and 50 years inclusive (at the time of enrolment)
- Evidence of having had at least one COVID-19 vaccine, with the last vaccination at least 3 months before enrolment
- Positive serology for SARS-CoV-2 at (pre)screening
- Sero-suitable as defined by having serum and/or nasal antibody titres less than a pre-defined cut-off of a defined assay(s) which will be specified in a separate SOP and based on accumulating antibody data
Key exclusion criteria (41 listed)
- History or evidence of any clinically significant or currently active cardiovascular, (including thromboembolic events), respiratory, dermatological, gastrointestinal, endocrine, haematological, hepatic, immunological, rheumatological, metabolic, urological, renal, neurological, psychiatric illness
- Any significant abnormality altering the anatomy or function of the nose or nasopharynx in a substantial way (including loss of or alterations in smell or taste), a clinically significant history of epistaxis (large nosebleeds) within the last 3 months, nasal or sinus surgery within 6 months of inoculation
- Clinically-active, symptomatic rhinitis (including hay fever) or history of severe rhinitis, or seasonal allergic rhinitis likely to be active at the time of inclusion into the study and/or requiring regular nasal corticosteroids on an at least weekly basis, within 30 days of admission to quarantine
- History of anaphylaxis and/or a history of severe allergic reaction or significant intolerance to any food or drug, as assessed by the Investigator
- Significant history or presence of drug or alcohol misuse (exceeding >28 units a week)
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 |
|---|---|---|
| SARS-CoV-2 Omicron EG.5.1 challenge agent 10^5 TCID5010^5 TCID50 This is a SARS-CoV-2 Omicron EG.5.1 challenge agent which has not been given in controlled human infection studies previously. | Biological | Group 1a: SARS-CoV-2 Omicron EG.5.1 |
| SARS-CoV-2 Omicron EG.5.1 challenge agent 10^6 TCID5010^6 TCID50 This is a SARS-CoV-2 Omicron EG.5.1 challenge agent which has not been given in controlled human infection studies previously | Biological | Group 1b: SARS-CoV-2 Omicron EG.5.1, Group 2: SARS-CoV-2 Omicron EG.5.1 |
| SARS-CoV-2 Omicron EG.5.1 challenge agent 10^4 TCID5010^4 TCID50 This is a SARS-CoV-2 Omicron EG.5.1 challenge agent which has not been given in controlled human infection studies previously | Biological | Group 1c: SARS-CoV-2 Omicron EG.5.1 |
Primary outcome
To assess the safety and human clinical response to intranasal challenge of SARS-CoV-2 EG.5.1 variant in healthy participants who are immunologically experienced against SARS-CoV-2.
Time frame: 28 Days
To evaluate the safety of Omicron variant SARS-CoV-2 challenge in healthy participants, by assessing: • Occurrence of AEs within 28 days post-viral challenge (Day 0 to Day 28)
To assess the safety and human clinical response to intranasal challenge of SARS-CoV-2 EG.5.1 variant in healthy participants who are immunologically experienced against SARS-CoV-2.
Time frame: 180 Days
To evaluate the safety of Omicron variant SARS-CoV-2 challenge in healthy participants, by assessing: • • Occurrence of SAEs related to the viral challenge (Day 0 to Day 180)
Selection of the SARS-CoV-2 Omicron EG.5.1 dose(s) required to induce laboratory confirmed upper respiratory tract infection in 50-70% of immunologically experienced, healthy participants following intranasal challenge
Time frame: 10 Days
Laboratory confirmed infection is defined as: two quantifiable (≥LLOQ) RT-PCR measurements from mid turbinate or throat samples, reported on 2 or more consecutive timepoints, starting from Day 2 (inclusive) post-inoculation and up to discharge from quarantine (Day 8 for uninfected participants or Day 10 for infected participants)
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 17 Jul 2026.
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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.
Christopher Chiu, BMBCh FRCP FRCPath PhD principal investigator
Imperial College London
5 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing SARS-CoV-2 Omicron EG.5.1 challenge agent 10^5 TCID50, SARS-CoV-2 Omicron EG.5.1 challenge agent 10^6 TCID50 and SARS-CoV-2 Omicron EG.5.1 challenge agent 10^4 TCID50 in people with SARS-CoV-2 (COVID-19), run by Imperial College London at 5 sites in United Kingdom.
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 13 inclusion and 41 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: looking for participants now, as of the sponsor's last update on 17 Jul 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 5 sites in United Kingdom. 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.
What does this phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Polly Fox-Sheehan, BSc, MSc (+4420 3313 1282, polly.fox@imperial.ac.uk), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
To assess the safety and human clinical response to intranasal challenge of SARS-CoV-2 EG.5.1 variant in healthy participants who are immunologically experienced against SARS-CoV-2. (time frame: 28 Days). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 17 Jul 2026.