Study of Recombinant Protein Vaccine Formulations Against COVID-19 in Healthy Adults 18 Years of Age and Older

The primary objectives of the study were:

* To describe the neutralizing antibody profile at Day 1, Day 22, and Day 36 of each study intervention group.
* To describe the safety profile of all participants in each age group and each study intervention group up to 12 months post-last injection.

The secondary objectives of the study are:

* To describe binding antibody profile at Day 1, Day 22, Day 36, Day 181 (Cohort 1) or Day 202 (Cohort 2), and Day 366 (Cohort 1) or Day 387 (Cohort 2) of each study intervention group.
* To describe the neutralizing antibody profile at Day 181 (Cohort 1) or Day 202 (Cohort 2) and at Day 366 (Cohort 1) and Day 387 (Cohort 2) of each study intervention group.
* To describe the occurrence of virologically-confirmed coronavirus disease (COVID-19)-like illness and serologically-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.
* To evaluate the correlation / association between antibody responses to SARS-CoV-2 Recombinant Protein and the risk of virologically-confirmed COVID-19-like illness and/or serologically-confirmed SARS-CoV-2 infection.

The duration of each participant's participation in the study was approximately 365 days (Cohort 1) and 386 days (Cohort 2) post last injection.

Eligibility Criteria:
Inclusion Criteria:

* Aged 18 years of age or older on the day of inclusion.
* Informed consent form had been signed and dated.
* Able to attend all scheduled visits and complied with all study procedures.

Exclusion Criteria:

* Participant was pregnant, or lactating, or of childbearing potential and not used an effective method of contraception or abstinence from at least 4 weeks prior to the first vaccination until at least 12 weeks after the last vaccination. To be considered of non-childbearing potential, a female was post-menopausal for at least 1 year or surgically sterile.
* Receipt of any vaccine in the 30 days preceding the first study vaccination or planned receipt of any vaccine in the 30 days following the last study vaccination except for influenza vaccination, which might be received at least 2 weeks before and a minimum of 2 weeks after study vaccines.
* Prior administration of a coronavirus vaccine SARS-CoV-2, SARS-CoV, Middle East Respiratory Syndrome).
* Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy, within the preceding 6 months; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months).
* History of SARS-CoV-2 infection, confirmed either clinically, serologically, or microbiologically
* Chronic illness or condition considered to potentially increase the risk for severe COVID illness or that, in the opinion of the Investigator, was at a stage where it might interfere with study conduct or completion.
* Receipt of any therapy known to had in-vitro antiviral activity against SARS-CoV-2 within 72 hours prior to the first blood drew.
* Health care workers provided direct participant care for COVID-19 participants.

The above information was not intended to contain all considerations relevant to a participant's potential participation in a clinical trial.