Comparing an intranasal COVID-19 vaccine to an mRNA booster in healthy adults

Randomized, Controlled, Multicenter Phase I/II Study Comparing the Safety and Immunogenicity of a Booster Dose of an Intranasal COVID-19 Vaccine Expressing SARS-CoV-2 N/S Recombinant Proteins With a Booster Dose of COVID-19 mRNA Vaccine in Healthy Adults (MUCOBOOST)

Phase1; Phase2 Interventional ANRS, Emerging Infectious Diseases · NCT06821126

This study is testing a new intranasal COVID-19 vaccine to see if it works as well as a standard mRNA booster in healthy adults.

Quick facts

PhasePhase1; Phase2
Study typeInterventional
Enrollment238 (estimated)
Ages18 Years to 60 Years
SexAll
SponsorANRS, Emerging Infectious Diseases Government
Drugs / interventionschemotherapy, radiation, prednisone
Locations5 sites (Dijon and 4 other locations)
Trial IDNCT06821126 on ClinicalTrials.gov

What this trial studies

This Phase I/II trial in France evaluates the safety and immunogenicity of an intranasal COVID-19 vaccine (LVT-001) compared to a standard mRNA booster (Pfizer-BioNTech) in healthy adult volunteers. The study begins with a Phase I dose escalation to assess safety across three cohorts, followed by a Phase II trial to evaluate the immunogenicity of the selected dose. Participants will receive either the intranasal vaccine or the mRNA booster, and their immune responses will be measured using nasal swabs. A total of 238 healthy volunteers will be enrolled across both phases.

Who should consider this trial

Good fit: Ideal candidates are healthy adults aged 18 to 60 who have received prior COVID-19 vaccinations.

Not a fit: Patients who have not received any COVID-19 vaccinations or those with significant health issues may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could provide a new, effective method for COVID-19 vaccination that is easier to administer and may enhance mucosal immunity.

How similar studies have performed: Other studies have shown promise with intranasal vaccines for COVID-19, but this specific approach is novel and untested in this context.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

1. Written informed consent obtained from the participant.
2. Be male or female between the ages of:

   1. ≥ 18 and ≤ 55 years for phase I
   2. ≥ 18 and ≤ 60 years for phase II.
3. Good general health as determined at the discretion of the investigator (vital signs, medical history, and physical examination).
4. BMI: 18,5 kg/m² ≤ BMI ˂30 kg/m².
5. Received at least 3 doses of a COVID-19 mRNA vaccine, last booster dose received at least 6 months prior to trial vaccine administration OR 2 doses of a COVID-19 mRNA vaccine and confirmed SARS-CoV-2 infection at least 6 months prior to inclusion in the trial.
6. Has expressed interest and availability to meet the trial requirements.
7. For a woman of childbearing potential, plan to be non-pregnant AND use of highly effective contraception from screening until the end of the trial.
8. Agree to abstain from donating blood/plasma or any other bodily fluids from the time of vaccination until 1 year after vaccination (only for LVT-001 vaccine).
9. Agree to stay in the geographical area of one of the clinical sites for the duration of the trial.
10. Agree to implement barrier measures as much as possible (washing hands and wearing a mask) against COVID-19 and respiratory infections between D0 and D28.
11. Agree to be registered in the computerized file of the Ministry of Health (VRB).
12. Be affiliated to French social security system.

Exclusion Criteria:

1. Temperature ≥ 38.0°C or symptoms of acute self-limiting illness such as upper respiratory tract infection or gastroenteritis within three days prior to vaccine dose.
2. Any form of contraindication to the trial vaccines tested.
3. History of chronic rhinitis, nasal septal defect, cleft palate, nasal polyps, or other nasal abnormality that might alter nasal mucosa and affect vaccine response.
4. A piercing or obstruction in the nostrils that could impede vaccine administration.
5. Previous nasal surgery or nasal cauterization.
6. History of frequent epistaxis.
7. Virologically documented (PCR or antigenic test) history of COVID-19 in the past 6 months.
8. Positive COVID-19 PCR test at screening visit.
9. Medical problems due to alcohol.
10. Illicit drug use within the past 12 months.
11. Participation in another trial within 60 days prior to the enrolment visit or planned participation during the present trial period in another clinical study investigating a vaccine, drug, medical device, or medical procedure.

    Note: Participation in an observational study is allowed.
12. Received influenza vaccination within 14 days prior to trial vaccination, or any other licensed vaccine within 4 weeks prior to study vaccination.
13. Vaccination with a COVID-19 vaccine other than mRNA vaccine.
14. Known sensitivity to any of the ingredients of the trial vaccines.
15. Known allergic reaction to plastic.
16. Positive serology for hepatitis B (HBsAg), C (anti-HCV antibodies) and HIV 1-2.
17. History of severe adverse events following vaccine administration including anaphylactic reaction and associated symptoms such as rash, breathing problems, angioedema, and abdominal pain, or a history of allergic reaction that could be triggered by a component of the SARS-CoV-2 vaccine at the time of the first vaccine administration.
18. Pregnancy positive test (βHCG test) or pregnancy or breastfeeding.
19. Received immunoglobulin or other blood products within three months prior to inclusion or planned administration before the trial completion.
20. Received an immunosuppressive therapy for underlying disease or a treatment with immunosuppressive or cytotoxic drugs or a cancer chemotherapy or radiation therapy within the previous 36 months.
21. Received drugs such as corticosteroids at a dosage \> 10 mg prednisone equivalent/day or inhalers corticosteroids, within 3 months prior to inclusion (excluding corticosteroid topical preparations for cutaneous application).
22. Abnormal and deemed clinically significant result by the investigator following the routine analyzes carried out at the time of the screening visit (any grade 4 biological result, even if deemed not clinically significant by the investigator, constitutes an exclusion criterion).
23. History of severe psychiatric disorders that may affect participation in the trial.
24. Any other serious chronic illness requiring immediate monitoring by a hospital specialist.
25. Any other condition that, in the opinion of the investigator, would compromise the safety or rights of a volunteer participating in the trial or render the subject unable to comply with the protocol.
26. Phase II only: Participants included in phase I will not be included in phase II.
27. Participants under legal protection (e.g., guardianship, tutorship).

Where this trial is running

Dijon and 4 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions HealthyCOVID-19Nasalvaccineintranasal
Last reviewed 2026-06-10 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.