Phase 1/2 Study of Chlamydia Trachomatis mRNA Vaccine in Adults Aged 18 to 29 Years

Inclusion Criteria: * Aged 18 to 29 years on the day of inclusion * New sex partner within the past 6 months, or more than one current sex partner, or partner with known previous or coexisting sexually transmitted infection (STI), or inconsistent condom use * A female participant is eligible to participate if she is not pregnant or breastfeeding and one of the following conditions applies: * Is of non-childbearing potential. To be considered of non-childbearing potential, a female must be surgically sterile. OR • Is of childbearing potential and agrees to use an effective contraceptive method from at least 4 weeks prior to study intervention administration until at least 4 weeks after the last study intervention administration. * A female participant of childbearing potential must have a negative highly sensitive pregnancy test (urine or serum as required by local regulation) at the screening visit and before each subsequent study intervention administration Exclusion Criteria: * Any screening laboratory parameter with laboratory abnormalities as per local reference range and that are greater than Grade 2 or deemed clinically significant in the opinion of the Investigator * Participants who are Chlamydia trachomatis (CT) and/or Neisseria gonorrhea (NG) NAAT positive at screening visit * Self-reported or documented seropositivity for HIV antigen and/or antibodies (Abs), hepatitis B virus surface antigen (HBsAg), hepatitis B core antibodies (HBcAbs), or hepatitis C vir…