The purpose of this study is to evaluate immunogenicity, epidemiological efficacy and safety of medicinal product GamEvac-Combi - Combined Vector-Based Vaccine against Ebola Virus Disease, 0.5 ml+0.5 ml/dose

This clinical trial is designed as a double blind randomized placebo-controlled study to evaluate immunogenicity of medicinal product GamEvac-Combi - Combined Vector-Based Vaccine against Ebola Virus Disease, 0.5 ml+0.5 ml/dose.

The study includes three periods: screening, administration of the investigated product and follow-up. Vaccine will be administered to groups of volunteers (each group will include not more than 40 volunteers at a time; a new group of volunteers cannot be hospitalized before the earlier vaccinated volunteers are discharged from the hospital. In total, 8 visits will be held, including a screening visit; two of the visits will take place during the inpatient stage and six - during the outpatient observation.

Study design in the both facilities will be the same for all volunteers, except that the biomaterial collected for immunogenicity evaluation from volunteers included in the study in the Russian Federation will be delivered directly to the testing laboratory; biomaterial from volunteers included in the study in the Republic of Guinea will undergo primary specimen processing, be frozen and stored under the assigned temperature conditions in the research center and, as biomaterial is accumulated, it will be transported in a fridge to the study site.

In addition, laboratory tests for such concomitant infectious diseases, as yellow fever, Denge fever, Ebola and Marburg virus diseases will be carried out for epidemiological indications (i.e. in the endemic regions if disease cases are reported).

Inclusion Criteria:

• Males and females within the age range from 18 to 60 years;
• written informed consent;
• absence of acute infectious diseases/relapses of chronic diseases at the time of vaccine administration and 7 days prior to the vaccination;
• absence of severe allergic diseases in the medical history (anaphylactic shock, Quincke's edema, polymorphic exudative eczema, serum disease)
• no serious post-vaccination complications in patient's history following the earlier administration of immunobiological products
• negative blood or urine test for pregnancy (for child-bearing age females) not more than 24 hours prior to the administration of the first dose of investigated product;
• absence of concomitant illnesses, especially dangerous or endemic for a particular region, proved by laboratory and/or clinical methods (malaria, yellow fever, Denge fever, Ebola or Marburg virus disease, poliomyelitis).
• negative results of HIV, hepatitis B and C and syphilis tests.
• adequate contraception for females and males of reproductive age.
• negative results of urine test for narcotic drug residues;
• negative result of breath alcohol test (in the expired air sample)
• absence of haematological malignancies
• absence of malignant neoplasms

Exclusion Criteria:

• - volunteer involvement in another study over the last 90 days;
• any immunization with vaccine over the last 30 days;
• symptoms of acute respiratory diseases within the last 7 days;
• administration of immunoglobulins or other blood products; taking immunosuppressive medications and/or immunomodulating agents over the last 3 months;
• pregnancy or breast feeding;
• exacerbation of allergic diseases, previous history of anaphylactic reactions or angioneurotic edema;
• previous history of hypersensitivity or allergic reactions to the administration of any vaccines;
• allergic reactions to the vaccine components;
• presence of a concomitant illness which might affect the evaluation of study results: active tuberculosis form, chronic liver and kidney diseases, serious thyroid dysfunction or other endocrine disorders (diabetes mellitus), severe hematopoietic diseases, epilepsy and other CNS disorders, myocardial infarction in the medical history, myocarditis, endocarditis, pericarditis, ischemic heat disease and other illnesses which, in opinion of the investigator, make patient ineligible for study enrollment or may affect the course of the study.
• blood donation (450 ml or more of blood or plasma) less than 2 months prior the study commencement date.