Study aim: Dose finding, safety and immunogenicity of recombinant protein sub-unit Covid vaccine developed by RAZI institute (Razi Cov Pars) Design: Phase I, randomized, double blind, placebo controlled trial will be conducted on 133 healthy volunteers including 13 sentinel and 120 participants randomly allocated to 4 study groups. Settings and conduct: Terhan Rasoul Akram Hospital Participants/Inclusion and exclusion criteria: Important inclusion criteria: Iranian nationals; Diploma and above; 18 - 55 years old; healthy based on clinical & laboratory criteria; Negative RT-PCR tests for COVID, Negative S antibody titer; Signed informed consent, Non pregnant or lactating (women); Important exclusion criteria: Any ongoing, symptomatic acute or chronic illness requiring medication or surgery (including respiratory/cardiac diseases, hypertension, diabetes, neurological diseases, serious psychiatric disorder & blood disorders that diagnosed by a physician); Breastfeeding; History of allergic diseases or reaction to the drug/vaccine Intervention groups: The four study groups consists of three vaccine groups receiving 5, 10, 20 µg/200µL intramascular doses on day 0 and 21 followed by 10 µg/200µl intranasal spray on day 51. The fourth group receives adjuvant only on day 0, and 21 (intramascular ) and 51 (intranasal spray). Main outcome variables: Primary outcomes: Immediate abnormal vital signs & anaphylactic reactions after vaccination: Local & Systemic adverse events within the first week post-vaccination: Abnormal lab. findings Secondary outcomes: Occurrence of COVID-19 disease 2 weeks after 2nd vaccine dose: SAEs, SUSARs, MAAEs, up to 6 months after last vaccine dose: Serum ELISA IgG level for SARS-CoV-2 antigens S، S1, N, S2, NTD، RBD; Serum ELISA IgA level for RBD; Neutralizing antibody activity cVNT; Cell-mediated immunity up to 5 months after start of vaccination.