The purpose of this double-blind, randomized, controlled study is to assess safety, reactogenicity, and preliminary immunogenicity of 202-CoV at multiple dose levels, administered as 2 injections (i.m) at 28 days apart in adult subjects 18 years of age and above.

Inclusion Criteria:

• Healthy individuals aged 18-59 years as well as 60 years and above who can provide legal identification (males and females are both required).
• Willing to participate in the study with informed consent prior to screening
• Negative in SARS-CoV-2 IgG and IgM test at screening.
• Women of childbearing potential must be using effective method of birth control for 14 days prior to the enrollment of the study vaccine/placebo and must agree to continue such precautions during the study until 30 days after the second dose of the study vaccine/placebo.
• Male subjects must agree to employ acceptable contraception from the day of first dose of the study vaccine/placebo until 30 days after the second dose of the study vaccine/placebo.

Exclusion Criteria:

• Confirmed or asymptomatic COVID-19 cases or SARS-CoV-2 infection(had positive in SARS-CoV-2 nucleic acid test or serological test).
• Had a history of traveling or residence in domestic area of high and moderate pandemic risk, overseas or epidemic areas, or had a history of contact with confirmed, asymptomatic or suspected COVID-19 cases within the past 14 days;
• History of SARS;
• Received SARS-CoV-2 vaccines for emergency use or approved SARS-CoV-2 vaccines;
• Individuals involving a clinical study within 6 months prior to the screening visit; or planning to participate in another clinical study during study period.
• Clinical laboratory abnormalities and with clinical significance judged by investigator
• Individual's systolic blood pressure ≥ 150mmHg and/or diastolic blood pressure ≥ 100mmHg at screening visit
• Axillary temperature >=37.3℃ prior to vaccination
• Individuals in other acute diseases, or in the acute phase of chronic diseases within 3 days prior to the signing of the informed consent form.
• Received immunoglobulin and/or blood product 3 months prior to the first vaccination.
• Presence of uncontrolled chronic pulmonary, cardiovascular, renal, hepatic, neurologic, hematologic or metabolic (including diabetes mellitus) disorders, which would include the potential subject in a high-risk category for SARS-CoV-2 infection and/or its complications as judged by the investigator..
• Individuals with a history of severe allergic reaction (throat swelling, difficult in breath, dyspnea, or shock).
• Individuals who have a history of severe adverse reaction associated with a vaccine or severe allergic reaction [e.g., anaphylaxis to any component of the study vaccines (S protein, Aluminum hydroxide, CpG adjuvant).
• Any autoimmune or immunodeficiency disease/condition [e.g. human immunodeficiency virus (HIV) infection, Systemic lupus erythematosus (SLE)]
• Received immunoglobulin, blood-derived products within 3 months prior to the first study vaccination.
• Abnormal coagulation function (such as coagulation factor deficiency, coagulation disease, platelet abnormality) obvious bruises or coagulopathy.
• Pregnant women or breastfeeding women.
• According to the judgment of the investigator, subject has or had any other symptoms, medical history and other factors that are not suitable for participating in this clinical trial.](streamdown:incomplete-link)