Study of Recombinant Protein Vaccines With Adjuvant as a Primary Series and as a Booster Dose Against COVID-19 in Adults 18 Years of Age and Older

Study at a glance

From the registry record, last updated by the sponsor on 18 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title

Immunogenicity and Safety of SARS-CoV-2 Recombinant Protein Vaccines With AS03 Adjuvant in Adults 18 Years of Age and Older as a Primary Series and Immunogenicity and Safety of a Booster Dose of SARS-CoV-2 Adjuvanted Recombinant Protein Vaccines (Two Monovalent and One Bivalent)

ClinicalTrials.gov ID

NCT04762680

Acronym / sponsor ID

VAT00002

Conditions

COVID-19

Phase

Phase 2/3

Study type

Interventional

Recruitment status

Completed

Enrolment

3,159 participants (actual)

Lead sponsor

Sanofi Pasteur, a Sanofi CompanyIndustry (pharma, biotech, devices)

Collaborators

GlaxoSmithKline

Study start

24 Feb 2021 (actual)

Primary completion

29 Jun 2023 (actual)

Study completion

29 Jun 2023 (actual)

First posted

21 Feb 2021 (actual)

Results

Posted 18 Sep 2025

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

Study design

Primary purpose

Prevention

Allocation

Randomised

Intervention model

Parallel groups

Masking

Quadruple blind (participant, care provider, investigator, outcomes assessor)

Number of arms

12

Model description

To address the emergence of variant strains, Sanofi Pasteur is developing monovalent and bivalent vaccines for use as universal late booster vaccines which will be studied in additional Phase 3 study cohorts that are added to the initial Phase 2 protocol cohorts. Supplemental Cohorts 1 and 2 will evaluate booster vaccine candidates.

Who may qualify

Ages

18 years and older

Sex

All

Healthy volunteers

Accepted

Age groups

Adult, Older adult

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Primary outcome

1. Phase 2 and Phase 3 (Cohorts 1, 2 and Comparator): Number of Participants With Immediate Unsolicited Adverse Events (AEs)

   Time frame: Up to 30 minutes after each vaccination (Phase 2: Postdose on Days 1 and 22; Phase 3: Between 4 to 10 months after priming vaccine)

   An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Immediate events were recorded to capture medically relevant unsolicited systemic AEs which occurred within the first 30 minutes after vaccination. An unsolicited AE was an observed AE that did not fulfill the conditions of solicited reactions, that is, pre-listed in the case report form (CRF) in terms of diagnosis and onset window post-vaccination.

2. Phase 2 and Phase 3 (Cohorts 1, 2 and Comparator): Number of Participants With Solicited Injection Site Reactions and Systemic Reactions

   Time frame: Up to 7 days after each vaccination (Phase 2: Postdose on Days 1 and 22; Phase 3: Between 4 to 10 months after priming vaccine)

   A solicited reaction was an "expected" adverse reaction (AR) (sign or symptom) observed and reported under the conditions (nature and onset) pre-listed in the protocol and CRF, and were considered to be related to the study vaccine administered. An injection site reaction was an AR at and around the injection site of the study vaccine. Systemic AR were all ARs that were not injection site reactions.

3. Phase 2 and Phase 3 (Cohorts 1, 2 and Comparator): Number of Participants With Unsolicited Adverse Events

   Time frame: Up to 21 days after each vaccination (Phase 2: Postdose on Days 1 and 22; Phase 3: Between 4 to 10 months after priming vaccine)

   An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An unsolicited AE was an observed AE that did not fulfill the conditions of solicited reactions, that is, pre-listed in the CRF in terms of diagnosis and onset window post-vaccination.

4. Phase 2 and Phase 3 (Cohorts 1, 2 and Comparator): Number of Participants With Serious Adverse Events (SAEs), Adverse Events of Special Interest (AESIs) and Medically Attended Adverse Events (MAAEs)

   Time frame: Phase 2 and Phase 3 Comparator: From first dose of study vaccine administration (Day 1) up to 387 days. Phase 3 Cohorts 1 and 2: From first dose of study vaccine administration (Day 1) up to 366 days.

   An SAE was defined as any AE that at any dose resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was a congenital anomaly/birth defect, or was an important medical event. An AESI (serious or non-serious) was 1 of scientific and medical concern specific to the Sponsor's study intervention or program, for which ongoing monitoring and rapid communication by the Investigator to the Sponsor could be appropriate. An MAAE was a new onset or a worsening of a condition that prompted the participant or participant's parent/guardian to seek unplanned medical advice at a physician's office or Emergency Department.

5. Phase 2: Geometric Mean Titers (GMTs) of Neutralizing Antibodies Against Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) D614G Strain at Day 1

   Time frame: Pre-vaccination on Day 1

   Neutralizing antibodies activity against SARS-CoV-2 D614G strain was measured with the neutralization assay (monogram assay) and the results were expressed as geometric mean titers.

6. Phase 2: Geometric Mean Titers of Neutralizing Antibodies Against SARS-CoV-2 D614G Strain at Day 36

   Time frame: Day 36

   Neutralizing antibodies activity against SARS-CoV-2 D614G strain was measured with the neutralization assay (monogram assay) and the results were expressed as geometric mean titers.

7. Phase 2: Number of Participants With >=2-Fold and >=4-Fold Rise in Serum Neutralization Antibody Titers Against SARS-CoV-2 D614G Strain at Day 36

   Time frame: Day 1 (pre-vaccination) and Day 36

   Neutralizing antibodies activity against SARS-CoV-2 D614G strain was measured with serum neutralization assay (monogram assay). Participants with neutralization antibody titers >=2-fold and >=4-fold increase from baseline (pre-vaccination) were analyzed.

8. Phase 2: Number of Responders as Determined by Neutralizing Antibody Titers Against SARS-CoV-2 D614G Strain at Day 36

   Time frame: Day 36

   Responders were participants who had baseline values below lower limit of quantification (LLOQ) with detectable neutralization titer above assay LLOQ at each pre-defined post-vaccination time point and participants with baseline values above LLOQ with a 4-fold increase in neutralizing antibody titers at each pre-defined post-vaccination time point.

9. Phase 3: Cohorts 1 and 2: Geometric Mean Titers of Neutralizing Antibodies Against SARS-CoV-2 D614G Strain and B.1.351 Variant at Day 1

   Time frame: Pre-vaccination on Day 1

   Neutralizing antibodies activity against SARS-CoV-2 D614G strain and B.1.351 variant was measured with the neutralization assay (monogram assay) and the results were expressed as geometric mean titers.

10. Phase 3: Cohorts 1, 2 and Comparator: Geometric Mean Titers of Neutralizing Antibodies Against SARS-CoV-2 D614G Strain and B.1.351 Variant at 14 Days Post-Vaccination

    Time frame: Cohorts 1 and 2: 14 days post-vaccination on Day 1, Day 15; Comparator: 14 days post-vaccination on Day 22, Day 36

    Neutralizing antibodies activity against SARS-CoV-2 D614G strain and B.1.351 variant was measured with the neutralization assay (monogram assay) and the results were expressed as geometric mean titers.

11. Phase 3: Comparator: Percentage of Responders as Determined by Neutralizing Antibody Titers Against SARS-CoV-2 D614G Strain and B.1.351 Variant at Day 36

    Time frame: Day 36

    Responders were participants who had baseline values below LLOQ with detectable neutralization titer above assay LLOQ at each pre-defined post-vaccination time point and participants with baseline values above LLOQ with a 4-fold increase in neutralizing antibody titers at each pre-defined post-vaccination time point. Percentages are rounded off to the tenth decimal place.

Results and safety

Loading the posted results from ClinicalTrials.gov…

Research links

• Official record on ClinicalTrials.govLast updated by the sponsor 18 Sep 2025.
• Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
• Derived from this study: PubMed 37533419de Bruyn G, Wang J, Purvis A, Ruiz MS, Adhikarla H, Alvi S, Bonaparte MI, Brune D, Bueso A, Canter RM, Ceregido MA, Deshmukh S, Diemert D, Finn A, Forrat R, Fu B, Gallais J, Griffin P, Grillet MH, Haney O, Henderson JA, Koutsoukos M, Launay O, Torres FM, Masotti R, Michael NL, Park J, Rivera-Medina DM, Romanyak N, Rook C, Schuerman L, Sher LD, Tavares-Da-Silva F, Whittington A, Chicz RM, Gurunathan S, Savarino S, Sridhar S; VAT00002 booster cohorts study team. Safety and immunogenicity of a variant-adapted SARS-CoV-2 recombinant protein vaccine with AS03 adjuvant as a booster in adults primed with authorized vaccines: a phase 3, parallel-group study. EClinicalMedicine. 2023 Jul 22;62:102109. doi: 10.1016/j.eclinm.2023.102109. eCollection 2023 Aug.
• Derived from this study: PubMed 35090638Sridhar S, Joaquin A, Bonaparte MI, Bueso A, Chabanon AL, Chen A, Chicz RM, Diemert D, Essink BJ, Fu B, Grunenberg NA, Janosczyk H, Keefer MC, Rivera M DM, Meng Y, Michael NL, Munsiff SS, Ogbuagu O, Raabe VN, Severance R, Rivas E, Romanyak N, Rouphael NG, Schuerman L, Sher LD, Walsh SR, White J, von Barbier D, de Bruyn G, Canter R, Grillet MH, Keshtkar-Jahromi M, Koutsoukos M, Lopez D, Masotti R, Mendoza S, Moreau C, Ceregido MA, Ramirez S, Said A, Tavares-Da-Silva F, Shi J, Tong T, Treanor J, Diazgranados CA, Savarino S. Safety and immunogenicity of an AS03-adjuvanted SARS-CoV-2 recombinant protein vaccine (CoV2 preS dTM) in healthy adults: interim findings from a phase 2, randomised, dose-finding, multicentre study. Lancet Infect Dis. 2022 May;22(5):636-648. doi: 10.1016/S1473-3099(21)00764-7. Epub 2022 Jan 25.
• VAT00002 Plain language Results SummaryLink provided by the sponsor.
• Individual participant dataSharing planned: Yes. Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org

Related trials for COVID-19

• Not yet recruitingPhase 1

  Phase I Open-Label Safety Trial of Pembrolizumab for Neurological Post- Acute Sequelae of SARS-CoV-2 (PD1-PASC I)

  Post-Acute COVID-19 Syndrome

• Active, not recruitingPhase 1

  A Safety and Immunogenicity Trial of OCU500, ChAd36 Vector Encoding SARS-CoV-2 Spike Vaccine Via Intranasal and Inhalational Routes in Previously Vaccinated Adults

  COVID-19

• Active, not recruiting

  Intervention to Address Disparate Mental Health Consequences of COVID-19 Pandemic on Latinx and African Newcomers

  Mental Health Issue, Mental Health Disorder

• Recruiting

  Home-Based Exercise Tele-Rehabilitation After COVID-19

  Post SARS-CoV2 (COVID-19)

• Not yet recruitingPhase 1

  A Safety, Reactogenicity and Immunogenicity Trial of RVX-sCPD9 Booster Intranasal COVID-19 Vaccine

  COVID -19

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.

66 sites in 7 countries: see every site and its status.