Study of Monovalent and Bivalent Recombinant Protein Vaccines 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 3 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title

A Parallel-group, Phase III, Multi-stage, Modified Double-blind, Multi-armed Study to Assess the Efficacy, Safety, and Immunogenicity of Two SARS-CoV-2 Adjuvanted Recombinant Protein Vaccines (Monovalent and Bivalent) for Prevention Against COVID-19 in Adults 18 Years of Age and Older as a Primary Series and Open-label Extension to Assess Immunogenicity, Safety, Efficacy of a Monovalent Booster Dose of SARS-CoV2 Adjuvanted Recombinant Protein Vaccine

ClinicalTrials.gov ID

NCT04904549

Acronym / sponsor ID

VAT00008 / VAT00008

Conditions

COVID-19

Phase

Phase 3

Study type

Interventional

Recruitment status

TerminatedReason stopped: The study was terminated as per Sponsor decision

Enrolment

23,670 participants (actual)

Lead sponsor

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

Study start

26 May 2021 (actual)

Primary completion

31 Aug 2024 (actual)

Study completion

31 Aug 2024 (actual)

First posted

27 May 2021 (actual)

Results

Posted 3 Jun 2026

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

4

Model description

The study is designed to demonstrate clinical efficacy of each of the two SARS-CoV-2 adjuvanted recombinant protein vaccines (monovalent and bivalent). In Stage 1, the monovalent vaccine will be evaluated against a placebo control. In Stage 2, the bivalent vaccine will be assessed against a placebo control.

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. Stage 1 and Stage 2: Number of Participants With Onset of Symptomatic Coronavirus Disease 2019 (COVID-19) Episode

   Time frame: From Day 36 up to Day 387

   Symptomatic COVID-19 was defined as virologically-confirmed SARS-CoV-2 infection accompanied by protocol-defined COVID-19-like illness (CLI).

2. Stage 1 and Stage 2: Number of Participants With Solicited Injection Site and Systemic Reactions

   Time frame: Up to 7 days after each vaccination (post-dose on Days 1 and 22)

   A solicited reaction was defined as an "expected" adverse reaction (AR) (sign or symptom) observed and reported under the conditions (nature and onset) pre-listed in the protocol and case report form (CRF) collected within 7 days after each injection and considered to be related to the corresponding 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 and included systemic manifestations such as headache, fever, as well as localized or topical manifestations that are not associated with the injection site.

3. Stage 1 and Stage 2: Number of Participants With Unsolicited Non-Serious Adverse Events (AEs)

   Time frame: Up to 21 days after each vaccination (post-dose on Days 1 and 22)

   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 was pre-listed in the CRF in terms of diagnosis and onset window post-vaccination.

4. Stage 1 and Stage 2: Number of Participants With Immediate Adverse Events

   Time frame: Up to 30 minutes after each vaccination (post-dose on Days 1 and 22)

   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 injection site and systemic AEs which occurred within the first 30 minutes after vaccination.

5. Stage 1 and Stage 2: Number of Participants With Medically Attended Adverse Events (MAAE), Serious Adverse Events (SAE), and Adverse Events of Special Interest (AESI)

   Time frame: From first dose of study vaccine administration (Day 1) up to 387 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.

6. Stage 1 and Stage 2: Percentage of Participants With Virologically-Confirmed SARS-CoV-2 Infection and/or Symptomatic COVID-19

   Time frame: From first dose of study vaccine administration (Day 1) up to 387 days

   Virologically-confirmed SARS-CoV-2 infection was defined as a positive result for SARS CoV-2 by nucleic acid amplification test (NAAT) on at least 1 respiratory sample. This included positive results by any NAAT that included tests performed outside the trial protocol if confirmed by the adjudication committee. Symptomatic COVID-19 was defined as virologically-confirmed SARS-CoV-2 infection accompanied by protocol-defined COVID-19-like illness. Percentages are rounded off to the tenth decimal place. Here, percentage of participants with virologically-confirmed SARS-CoV-2 infection and/or symptomatic COVID-19 (regardless of adjudication) are reported.

Results and safety

Loading the posted results from ClinicalTrials.gov…

Research links

• Official record on ClinicalTrials.govLast updated by the sponsor 3 Jun 2026.
• Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
• Derived from this study: PubMed 37716365Dayan GH, Rouphael N, Walsh SR, Chen A, Grunenberg N, Allen M, Antony J, Asante KP, Bhate AS, Beresnev T, Bonaparte MI, Celle M, Ceregido MA, Corey L, Dobrianskyi D, Fu B, Grillet MH, Keshtkar-Jahromi M, Juraska M, Kee JJ, Kibuuka H, Koutsoukos M, Masotti R, Michael NL, Neuzil KM, Reynales H, Robb ML, Villagomez Martinez SM, Sawe F, Schuerman L, Tong T, Treanor J, Wartel TA, Diazgranados CA, Chicz RM, Gurunathan S, Savarino S, Sridhar S; VAT00008 Study Team. Efficacy of a bivalent (D614 + B.1.351) SARS-CoV-2 recombinant protein vaccine with AS03 adjuvant in adults: a phase 3, parallel, randomised, modified double-blind, placebo-controlled trial. Lancet Respir Med. 2023 Nov;11(11):975-990. doi: 10.1016/S2213-2600(23)00263-1. Epub 2023 Sep 13.
• VAT00008 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

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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. This study is not recruiting at the moment.

The record lists no contact. Use the official record to reach the sponsor.

86 sites in 11 countries: see every site and its status.