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New vaccine aims to supercharge COVID-19 immunity

NCT ID NCT06810934

What the study statuses mean

This study's is highlighted.

Recruitment status, easiest to join first

Recruiting now This study
This trial is taking on new participants right now.
Not yet recruiting
Registered, but not yet taking participants.
By invitation only
Not open to general applications. Only people the study team invites can take part.
Paused
Paused for now. It may or may not start again.
Ongoing
Running, but no longer taking on new participants.
Completed
The trial has finished. Results may not be published yet.
Stopped early
Stopped early, before it reached the end. That can be for many reasons, including safety.
Cancelled
Cancelled before anyone took part.

Expanded access (not trials)

Expanded access
Not a trial. This treatment can be requested outside a study, case by case, for people who qualify.
Expanded access (paused)
Not a trial. The treatment can normally be requested outside a study, but is unavailable right now.
Expanded access (ended)
Not a trial. The treatment could once be requested outside a study, but no longer can.
Approved
The treatment has been approved, so it is available normally rather than through this programme.

When the status isn't known

Details not published
The full record has not been published yet, so there is little to show here.
Status unknown
This status has not been confirmed recently, so it may be out of date.

First seen Jun 27, 2026 · Last updated Aug 19, 2026 · Updated 2 times

Summary

This study is testing two experimental COVID-19 booster vaccines in 80 healthy volunteers aged 40-64. One vaccine includes an extra component called 's3' designed to improve the body's immune response. Participants will receive a single dose of either vaccine or a placebo and be monitored for side effects and immune responses. The goal is to see if these vaccines are safe and if the s3 component leads to broader, longer-lasting protection.

What this could mean

Our plain-language read of the trial. This is informational only, not medical advice or a prediction.

Active substance
Ad35-vectored SARS-CoV-2 RBD (XBB.1.5) vaccine
What this could lead to
If successful, this could lead to a more effective COVID-19 booster that provides broader and longer-lasting protection against current and future variants.
What could go wrong
This is an early-phase trial with only 80 participants, so results may not apply to the general population. The vaccine may not produce stronger immunity than existing boosters, and side effects are still being studied.

This is an AI summary of the original study and may miss details. Read our disclaimer.

Study facts

What this study's own registry entry says, in plain language.

Phase

Phase 1/2

Runs two stages together: safety and dose first, then whether the treatment works.

Participants

About 80 people

The number the study aims to enrol. It can still change while the study runs.

Started

Oct 2025

Expected to finish

Oct 2029

An estimate. End dates often move.

Lead sponsor

Other sponsor

The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.

Who can take part

This study's own entry requirements. Only the study team can say for certain whether you qualify.

Ages

40 to 64 years

Sex

Anyone

Healthy volunteers

Accepted

You do not need to have the condition being studied to take part.

Show the full entry requirements

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Individuals 40 - 64 years of age 2. Received at least two doses of a COVID-19 mRNA vaccine (Moderna or Pfizer) \> 120 days before study entry 3. Nasal SARS-CoV-2 negative by molecular (polymerase chain reaction, PCR) testing at screening 4. The following laboratory criteria must be met at screening: 1. Total white blood cell (WBC) count \> 3500 cells/mm3 2. Absolute neutrophil count (ANC) \> 1500 cells/mm3 3. Hemoglobin \> 13.5 g/dL if male sex and \> 12.0 g/dL if female sex 4. Platelet count \> 140,000/uL 5. Estimated creatinine clearance (CrCl) \> 50 mL/min by Cockroft-Gault equation 6. Total bilirubin ≤ 1.1x upper limit of normal (ULN) 7. Aspartate aminotransferase (AST) ≤ 1.3x ULN 8. Alanine aminotransferase (ALT) ≤ 1.3x ULN 5. Individuals of reproductive potential must have a negative serum or urine beta-human chorionic gonadotropin (ß-HCG) test at screening and within 48 hours prior to entry. Reproductive potential is defined as: * Participants who have reached menarche * Participants who have not been post-menopausal for at least 12 consecutive months with follicle-stimulating hormone (FSH) ≥40 IU/mL or 24 consecutive months if an FSH is not available * Participants who have not undergone surgical contraception (e.g., hysterectomy, bilateral oophorectomy, bilateral tubal ligation, or bilateral salpingectomy) NOTE: Participants who have undergone bilateral tubal ligation within the 24 weeks prior to screening are considered to be of reproductive potential and, if participating in sexual activity that could lead to pregnancy, contraception is required as per 5.2.2 exclusion criterion 2. 6. Able and willing to provide informed consent Exclusion Criteria: Participants are excluded from the study if any of the following criteria are met: 1. Pregnant or breastfeeding 2. For participants capable of becoming pregnant and engaging in sexual activity that can lead to pregnancy, unwillingness to use contraception during participation in the study. For participants capable of becoming pregnant, two of the following forms of contraception are required through 30 days following administration of study intervention, one of which must be a barrier method: 1. Condoms (male or female) with or without a spermicidal agent 2. Diaphragm or cervical cap with spermicide 3. Intrauterine device (IUD) 4. Hormone-based contraceptive such as oral birth control pills 3. Known close contact with anyone with confirmed SARS-CoV-2 infection (defined as positive SARS-CoV-2 nucleic acid or antigen testing by laboratory-based or home self-test) within 2 weeks prior to expected study entry 4. Plan to receive a non-study SARS-CoV-2 vaccine within 8 weeks after study entry 5. HIV infection 6. Hepatitis B core antibody or hepatitis B surface antigen positive at screening 7. Current active hepatitis C. Participants must be hepatitis C virus (HCV) antibody negative or have evidence of cleared HCV infection. If the participant is HCV antibody positive or indeterminate, an unquantifiable HCV RNA result (below lower limit of quantification, either target detected or target not detected) within 42 days prior to study entry is required. Those who are currently receiving HCV antiviral therapy or those who have received HCV treatment in the last 3 months prior to study entry will be excluded. 8. History of cirrhotic liver disease 9. History of thrombosis with thrombocytopenia syndrome (TTS), immune thrombocytopenia, thromboembolic events, capillary leak syndrome, other thrombotic disease or known increased risk of thrombosis due to genetic disorders or malignancy 10. History of or active autoimmune disease that has required systemic immunosuppressive or immunomodulatory therapy 11. History of myocarditis, pericarditis, or myopericarditis 12. Potential myocarditis or pericarditis identified at screening, defined as high-sensitivity troponin I (hsTnI) \> ULN or 12-lead ECG compatible with pericarditis WITH compatible symptoms (regardless of troponin I level) at screening 13. History of Guillain-Barré syndrome 14. History of coagulopathy or bleeding disorder considered a contraindication to intramuscular injection or phlebotomy 15. Symptomatic acute or chronic illness requiring ongoing medical or surgical care, including requirement for new medications, in the past 3 months. Transient illnesses or injuries that are resolved prior to screening are not exclusionary. Minor adjustments in stable therapy for chronic conditions such as hypertension are not exclusionary. Use of over-the-counter medications for any acute or chronic illness is also not exclusionary. 16. Serious medical or psychiatric illness that, in the opinion of the site investigator, would interfere with the ability to adhere to study requirements or to give informed consent 17. Treatment with systemic immunosuppressive or immunomodulatory drugs, and/or exposure to any immunosuppressive/immunomodulatory drug in the 30 days prior to study entry (e.g. corticosteroid therapy equal to or exceeding a dose of 20 mg/day of prednisone for more than 10 days, interleukins, interferons, methotrexate, rituximab, and cancer chemotherapy). Use of topical, inhaled, intra-articular, or nasal steroid use is not exclusionary. 18. Active malignancy or history of malignancy within the 4 years prior to study entry. Non-melanoma skin cancers (such as basal or squamous cell skin cancers) and non-invasive cervical or anal intraepithelial lesions are not exclusionary. 19. History of solid organ or hematopoietic stem cell transplantation 20. History of primary immunodeficiency disorder 21. Ongoing complications or morbidity associated with prior diagnoses of malignancies requiring continued medical or surgical intervention. Chronic stable complications or morbidity not requiring new medications or other medical or surgical intervention in the past 3 months are not exclusionary. 22. Administration or planned administration of blood products or licensed non-SARS-CoV-2 vaccines \<14 days prior to or within 14 days after study entry 23. Receipt of any antibody-based therapy (investigational or approved) for prophylaxis or treatment of COVID-19 in the preceding 6 months 24. Receipt of immunoglobulin therapy in the year prior to study entry or scheduled or anticipated immunoglobulin administration during the study period. 25. Prior receipt of any non-mRNA SARS-CoV-2 vaccine 26. Receipt of any SARS-CoV-2 vaccination in the 120 days prior to study entry 27. Documented SARS-CoV-2 infection in the 120 days prior to study entry 28. History of anaphylaxis, urticaria, or other significant adverse reaction requiring medical intervention (medications requiring a prescription or surgical intervention) after receipt of a vaccine or intervention that includes one or more of the same components contained in the study product 29. Have participated in an interventional clinical study within 28 days prior to screening (based on medical history interview) or plans to do so while participating in this study 30. Any clinical concerns as determined by the investigator that might affect the potential participant's safety in the study.

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Conditions

The condition(s) this trial relates to.

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

How to take part

Only the study team decides who joins. These are the ways to reach them.

  1. The places running it

    2 sites. The list below names each one and where it is.

  2. The official record

    ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.

    Open the record ↗

  3. A doctor treating you

    A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.

Contacts and locations

Locations

  • UCLA Westwood

    RECRUITING

    Los Angeles, California, 90095, United States

  • UCSF Community and Clinical Research Center

    RECRUITING

    San Francisco, California, 94110, United States

More trials for these conditions

Other studies related to the condition(s) this trial covers.