IRCT20210620051639N3 IRCT 2021-12-23 Bagheiat-allah University of Medical Sciences Phase 3 Clinical Trial to evaluate the Immunogenicity and Safety of Covid19 Recombinant RBD Protein Vaccine (Noora Vaccine) as a Booster Vaccine after injection of existing Vaccines in IRAN Phase 3 Clinical Trial to evaluate the Immunogenicity and Safety of Covid19 Recombinant RBD Protein Vaccine (Noora Vaccine) as a Booster Vaccine after injection of existing Vaccines in IRAN 2021-12-26 anticipated 10300 Complete https://irct.ir/trial/60796 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Used, Assignment: Parallel, Purpose: Prevention, Randomization description: In this study, Randomization process in immunogenicity assessment section is performed one step before the onset of recruitment. For this purpose, 60 random block sequences with size 6 will be produced so that for every 4 volunteers receiving the recombinant vaccine, 2 volunteers will receive placebo. There is no randomization process in the safety assessment section which will be performed before and after, Blinding description: The blinding process in the immunogenicity assessment section of this study, which will be performed on a sample size of 300 people, is performed in a double-blind manner. For this purpose, the placebo is exactly the same as the vaccine and is prepared by the manufacturer with the same volume, color and other specifications and will be labeled by an independent group based on randomization codes. Obviously, the researchers, the evaluation team of the volunteers, the vaccinators and the volunteers will be completely unaware of the type of product received. In the safety assessment section (on a sample size of 10000 people), the study will be open labeled and the blinding process will not be used. 3 Covid 19. Intervention 1: Intervention Group: Injection of a dose of 80 micrograms of recombinant RBD protein vaccine intramuscularly (deltoid muscle) in 10000 participants in affiliated centers of Baqiyatallah Hospital and 200 participants in Shahid Soleimani Clinical Trial Center. Intervention 2: Control group: Injection of a placebo intramuscularly (deltoid muscle) in 100 participants in Shahid Soleimani Clinical Trial Center. No - There is not a plan to make this available Justification or reason for not sharing IPD is There is not a plan to make this available