Phase IIB Study of Recombinant Novel Coronavirus Vaccine

There are 4 planned site visits in total: V1 (day0), V2 (day21), V3 (month 3), V4 (month 6) Healthy adults aged 18 years and above in Argentina will be informed by a procedure approved by the ethical review committee before consent is sought to be a volunteer. After passing the physical examination and screening according to the inclusion and exclusion criteria, they will be eligible to participate in this study. Group B is a comparator group, in which samples stored corresponding to individuals who have already received 2 doses of Sputnik V will be used for the immunogenicity evaluation. Study Procedures * Informed consent * Check inclusion and exclusion criteria All inclusion and exclusion criteria will be checked at the screening in-person visit and be reviewed at each in-person visit. * Collect demographic data and contact information * Medical history Obtain the participant's medical history by interview and/or review of the participant's medical records and record any pre-existing conditions or signs and/or symptoms present prior to injection in the EDC. This will include reviewing of any health condition that may prevent the participant from enrolling in the study, such as an unstable health condition or known positive HIV status (with less than 200 CD4 cells/mL). * Check contraindications, warnings and precautions to injection Contraindications, warnings and precautions to injection must be checked before vaccination. * Urine Pregnancy Test/Birth Control Women of child-bearing age will be asked to perform a urine pregnancy test at the day of enrollment. The result of the urine pregnancy test must be negative. In addition, participants who are able to become pregnant or could impregnate a partner are required to have used approved contraception at least 30 days prior to the study vaccination and for 90 days' post-vaccination. * Physical examination Screening conclusion Participants will be deemed eligible to participate upon reviewing medical history and inclusion and exclusion criteria. This will occur prior to vaccination. * Study group and treatment number allocation The eligible participants will be enrolled into Group A. Each participant will be assigned a treatment identification number (Subject ID). * Check and record prior medications and concomitant medication/injection * Check and record intercurrent medical conditions * Pre-vaccination serology Approximately 10 mL of whole blood will be collected from each participant in Group A at Day 0 and separated for serum. * Injection of study vaccine After completing all prerequisite procedures prior to injection, one dose of the assigned vaccine will be administered IM in the deltoid muscle of the upper arm for participants in Group A. * Safety participant contacts Participants in group A need to record any AEs they may experience within 21 days post-vaccination. There is an on-site visit on the 21st day post-vaccination and the subjects need to submit their diary card. Following up serology All participants in group A will have an in-person visit at Day 21, Month 3, and Month 6 post-vaccination of either Ad5-nCoV. Approximately 10 mL of whole blood will be collected from each participant and separated for serum.