The purpose of the VBE00009 study is to evaluate the safety, efficacy and immunogenicity of 2 administrations of the Acne mRNA vaccine candidate at single dose level in participants aged 18 to 45 years with mild acne. This study will consist of a Core Study followed by an optional Long-Term Extension (LTE). Core Study will include a Sentinel Cohort and a Main Cohort, with the Sentinel Cohort assessing the safety in a stepwise manner. If the participants consent to the LTE, they will be followed up for an additional 30 months after the last planned visit in the Core Study, to assess the long term effects of the vaccine.

Inclusion Criteria:

• Participants who are overtly healthy as determined by medical evaluation including medical history, physical examination, and laboratory tests as judged by the investigator

• Clinical diagnosis of mild facial acne vulgaris with:

  • IGA score of mild (grade 2 on the 5-grade IGA scale) AND
  • between 10 to 24 non-inflammatory lesions (ie, open and closed comedones) AND
  • between 5 to 19 inflammatory lesions (ie, papules and pustules) AND
  • no nodulocystic lesions (ie, nodules and cysts)

Exclusion Criteria:

Participants are excluded from the study if any of the following criteria apply:

• Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy, within 6 months prior to the first study intervention administration; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months)
• Known systemic hypersensitivity to any of the study intervention components; history of a life-threatening reaction to the study interventions used in the study or to a product containing any of the same substances; any allergic reaction (eg, anaphylaxis) after administration of mRNA coronavirus disease 2019 (COVID 19) vaccine
• Previous history of or undergoing (suspected or confirmed) myocarditis and/or pericarditis and/or myopericarditis
• Skin pathology or condition that, in the investigator's opinion, could interfere with the evaluation of the study intervention or requires use of interfering topical, systemic, or surgical therapy
• Excessive facial hair, facial tattoos, facial skin disorders, skin reactions that may interfere with the study assessments in the investigator's opinion (including - but not limited to - actinic keratosis, eczema, psoriasis, seborrheic dermatitis, rosacea, acute or recent sunburn) or skin infection
• Receipt of immune globulins, blood or blood-derived products in the past 3 months
• Self-reported or documented seropositivity for human immunodeficiency virus (HIV), hepatitis B virus, or hepatitis C virus

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

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

Core Study:

Sentinel Cohort: modified double-blind

• Investigators, participants, laboratory personnel will be blinded
• Clinical site staff preparing/administering the study vaccines will be unblinded
• Sponsor study staff involved in early safety data reviews (ESDRs) will be unblinded at the time of the ESDR Main Cohort: modified double-blind
• Investigators, participants, laboratory personnel and Sponsor study staff will be blinded
• Clinical site staff preparing/administering the study vaccines will be unblinded
• Sponsor staff involved in the Internal Firewall Committee will be unblinded at the time of the interim analysis

Long-term Extension:

Sentinel and Main Cohorts: double-blind

• Investigators, participants, laboratory personnel and Sponsor study staff will be blinded