An Early Phase 1 interventional study of SARS-CoV-2 omicron virus dose arm 1 and SARS-CoV-2 omicron virus dose arm 2 in SARS-CoV-2 Infection, sponsored by Hvivo. Completed at 1 site in United Kingdom. Open to participants aged 18 Years to 40 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-11-21.
Sponsored by Hvivo · Early Phase 1, Interventional, and Other
An Exploratory Study to Establish the Dose, Safety and Pathogenicity of a SARS-CoV-2 Omicron Challenge Strain (BA.5) in Healthy Participants 18 to 40 Years of Age
This is an exploratory study of an SARS-CoV-2 Omicron (BA.5) challenge strain to determine the optimum safe infectious titer of challenge agent in healthy participants 18 to 40 years of age.
Up to 90 participants who meet all study inclusion and no exclusion criteria will be allocated to one of the three dose escalating cohorts (Dose 1, Dose 2 or Dose 3), with up to 30 participants in each dose group, to receive one dose of SARS-CoV-2 omicron. Based on the outcome of each cohort the next cohort may receive a high or lower dose than the previous cohort.
Each participant will remain in the study for approximately 9 months from screening to the last clinic visit.
The study is divided into three phases:
Quarantine phase: Participants will stay in the quarantine unit for approximately 17 days (from Day -2/-1 to Day 14).
One or two days prior to the day of inoculation with the challenge virus, participants will be admitted to quarantine where their eligibility will be reassessed. If participants remain eligible for the study, they will receive the challenge virus on Day 0. Participants will undergo a range of clinical assessments and safety monitoring for the entirety of their stay in quarantine. Participants will be discharged from the quarantine unit on Day 14 (or may remain longer at the principal investigator's discretion). If participants do not become infected with the virus they may be discharged earlier on Day 8.
7,990 studies on the registry are indexed under COVID-19; 466 are open to participants now.
This study's enrollment of 36 is below the median of 102 across 4,364 interventional studies indexed under COVID-19.
Browse COVID-19 studies →Hvivo is the lead sponsor of 13 studies on the registry; 2 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
From a breathing test (spirometry): how much air you can blow out in the first second. Often given as a percentage of what is expected for your age, height and sex.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
FEV1
From a breathing test (spirometry): how much air you can blow out in the first second. Often given as a percentage of what is expected for your age, height and sex.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Low dose, expected to be approximately 10\^4 tissue culture infective dose 50% (TCID50)/mL (titer may be adjusted based on stock titer)
Biological: SARS-CoV-2 omicron virus dose arm 1
Medium dose, expected to be approximately 10\^5 tissue culture infective dose 50% (TCID50)/mL (titer may be adjusted based on stock titer)
Biological: SARS-CoV-2 omicron virus dose arm 2
High dose, expected to be approximately 10\^6 tissue culture infective dose 50% (TCID50)/mL (titer may be adjusted based on stock titer)
Biological: SARS-CoV-2 omicron virus dose arm 3
Low dose, approximately 10\^4 TCID50/mL
Medium dose, approximately 10\^5 TCID50/mL
High dose, approximately 10\^6 TCID50/mL
Occurrence of Adverse Events related to the viral challenge
Number of participants with challenge Agent-emergent adverse events (AEs) at least possibly related to the viral challenge from viral challenge (Day 0) up to the Day 28 follow-up
Time frame: Day 0 to Day 28
Occurrence of Serious Adverse Events and Medically Attended Adverse Events, related to the viral challenge
Occurrence of serious AEs (SAEs) and Medically Attended Adverse Events (MAAEs) related to the viral challenge from viral challenge (Day 0) up to the Day 180 follow-up
Time frame: Day 0 to Day 180
Induces laboratory-confirmed infection in ≥40% of inoculated participants
Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR)-confirmed SARS-CoV-2 omicron infection, defined as 2 quantifiable (≥ lower limit of quantification \[LLOQ\]) qRT-PCR measurements (reported over 4 planned consecutive assessments within 48 hours), from Day 1 pm to planned discharge from quarantine (Day 14 am).
Time frame: Day 1 to Day 14
Plan to share: No
No publications or documents are linked to this record.
Ran from Dec 2024 to primary completion in Oct 2025, 10 months.
Of 233 industry-sponsored phase 1 interventional studies under COVID-19, half reached primary completion within 6 months of starting (the median), counting those still running; a quarter within 2 and three quarters within 12. This study's 10 months is above that.
Counting every sponsor, half of 384 studies reached it within 7 months; a quarter within 3 and three quarters within 15.
How these figures are worked out, and which studies are left out of them.
This study is completed, as verified in Oct 2025. You cannot join it, but the record below documents what was studied.
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