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Study of Recombinant Protein ...

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

Last Updated: 2025-09-18

Study Results

Results available

Outcome measurements, participant flow, baseline characteristics, and adverse events have been published for this study.

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Basic Information

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Recruitment Status

COMPLETED

Clinical Phase

PHASE2/PHASE3

Total Enrollment

3159 participants

Study Classification

INTERVENTIONAL

Study Start Date

2021-02-24

Study Completion Date

2023-06-29

Brief Summary

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The primary objectives of the study are:

To assess the safety profile of the study vaccines in each study intervention group.

To assess the neutralizing antibody profile after primary series vaccination in SARS-CoV-2-naïve adults.

To demonstrate that a booster dose of monovalent or bivalent SARS-CoV-2 vaccine given to adults previously vaccinated with an authorized/approved COVID-19 vaccine induces an immune response that is non-inferior to the response induced by a twodose priming series with the monovalent vaccine, and superior to that observed immediately before booster.

The secondary objectives of the study are:

To assess the neutralizing and binding antibody profiles after primary series vaccination at pre-defined time points during the study.

To assess the neutralizing and binding antibody responses of booster vaccination.

To describe the occurrences of laboratory-confirmed symptomatic COVID19 after primary series and booster vaccination.

To describe the occurrences of serologically-confirmed SARS-CoV-2 infection after primary series vaccination.

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Detailed Description

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The duration of each participant's participation in the study will be approximately:

Original Phase 2 part: 365 days postinjection 2 (ie, 386 days total). Supplemental Cohorts 1 and 2: 365 days post-booster injection (ie, 366 days total).

Conditions

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COVID-19

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

PARALLEL

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.

Primary Study Purpose

PREVENTION

Blinding Strategy

QUADRUPLE

Participants Caregivers Investigators Outcome Assessors

In the original Phase 2 part, participants, outcome assessors, Investigators, laboratory personnel, and sponsor study staff are blinded to intervention group; and those preparing the study interventions are unblinded to vaccine assignment group.

The supplemental Cohort 1 intervention group and Supplemental Cohorts Comparator Group will be open-label. Supplemental Cohort 2 will involve sequential randomization to main arms then exploratory arms, and the intervention will be modified double-blind (observer-blinded, as described).

Study Groups

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Phase 2 Cohort -SARS-CoV-2 vaccine Formulation 1

2 injections of SARS-CoV-2 vaccine Formulation 1 at Day 1 and Day 22

Group Type EXPERIMENTAL