Study to Assess the Safety and Immunogenicity of a Chikungunya Virus Vaccine Candidate (VLA1553) in Healthy Volunteers

Inclusion criteria

• Aged 18 to 45 years on the Day of screening;
• Has a BMI of ≥ 18.5 and < 30 kg/m2 on the Day of screening;
• Understanding of the study and its procedures, agrees to its provisions, and gives written informed consent prior to any study-related procedures;
• Generally healthy as determined by the Investigator's clinical judgement based on medical history, physical examination and screening laboratory tests;
• If female, subject is of non-childbearing potential. The definition of non-childbearing potential includes the following:

• Surgically sterile (e.g., hysterectomy with or without oophorectomy; fallopian tube ligation; endometrial ablation), at least 30 days prior to signature of the Informed Consent form;
• At least 5 years post-menopause (i.e., 6 years post last menstrual period), or menopause confirmed by follicle-stimulating hormone (FSH) testing.

Exclusion criteria

• History of known CHIKV infection;
• Plans to travel to areas with active CHIKV transmission during the course of the study or history of travel to an endemic CHIKV area within 4 weeks prior to study enrollment;
• Participation in a clinical study involving an investigational CHIKV vaccine;
• Receipt of an inactivated vaccine within 4 weeks or live vaccine within 8 weeks prior to vaccination in this study;
• Positive test results for human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg) or hepatitis C virus (HCV);
• (1) Abnormal laboratory liver function values (≥ grade 1), (2) any grade 1 abnormal lab values deemed clinically relevant by the Investigator, and (3) any ≥ grade 2 abnormal lab values irrespective of clinical significance at screening;
• Clinically significant abnormal ECG at screening;
• History of significant cardiovascular, respiratory (including asthma), metabolic, neurological, hepatic, rheumatic, autoimmune, hematological, gastrointestinal or renal disorder;
• History of immune-mediated or clinically significant arthritis/arthralgia;
• History of malignancy other than squamous cell or basal cell skin cancer, unless there has been surgical excision that is considered to have achieved a cure;
• Disease or recent or current treatment that can be expected to influence immune response as specified in the protocol;
• History of severe hypersensitivity reactions or anaphylaxis;
• History of any vaccine related contraindicating event (e.g., anaphylaxis, allergy to components of the candidate vaccine, other known contraindications);
• Acute febrile infections within two weeks prior to vaccination;
• Subject is of childbearing potential or lactating at the time of enrollment;
• Blood donation within 30 days or receipt of blood-derived products (e.g. plasma) within 90 days prior to vaccination in this study or during the course of the study;
• A rash, dermatological condition or tattoos that would, in the opinion of the Investigator, interfere with injection site reaction rating;
• Known or suspected problem with alcohol or drug abuse as determined by the Investigator;
• Any condition that, in the opinion of the Investigator, may compromise the subjects well-being, might interfere with evaluation of study endpoints, or would limit the subject's ability to complete the study;
• Participation in another clinical study involving an investigational medicinal product within 30 days prior to study enrollment or during the course of this study;
• Member of the team conducting the study or in a dependent relationship with one of the study team members. Dependent relationships include close relatives (i.e., children, partner/spouse, siblings, parents) as well as employees of the Investigator or site personnel conducting the study.