Study of the Commercial Scale SARS-CoV-2 Vaccine Against the Pilot Scale Among Adults, and Bridging Study of the Immunogenicity in Elderly Against That in Adults

This study is a randomized, double-blinded clinical Trial, to evaluate the non-inferiority of the commercial scale Inactivated SARS-CoV-2 vaccine against that of the pilot scale among adults aged 26-45 years, and the open-labelled, bridging non-inferiority of the vaccine induced immunogenicity in elderly against that in adults. The experimental vaccine was manufactured by Sinovac Research & Development Co.,Ltd. Totally 1040 subjects，including: 130 subjects aged 18~25 years; 520 subjects aged 26~45 years, with 260 in each group; 130 subjects aged 46~59 years; 260 subjects aged ≥60 years.

Subjects will be assigned to receive two doses of medium-dosage vaccine on the schedule of 0,14.

Inclusion criteria

• Healthy adults aged 18-59 or elderly aged ≥60 years;
• Proven legal identity.

Exclusion criteria

• Travel/residence history of communities with reported cases within 14 days before trial;
• History of exposure to Novel Coronavirus infection (nucleic acid positive) within 14 days prior to the trial;
• Exposed to patients with fever or respiratory symptoms from communities with reported cases within 14 days prior to the trial;
• Two or more cases of fever and/or respiratory symptoms in a small area such as home, office, school and class within 14 days prior to the trial;
• History of SARS-CoV-2 infection;
• History of asthma, history of allergy to vaccines or vaccine ingredients, and severe adverse reactions to vaccines, such as urticaria, dyspnea, and angioneurotic edema;
• Congenital malformations or developmental disorders, genetic defects, severe malnutrition, etc.;
• Autoimmune disease or immunodeficiency/immunosuppression;
• Patients with serious chronic diseases, serious cardiovascular diseases, uncontrolled hypertension and diabetes, liver and kidney diseases, malignant tumors, etc.;
• Serious neurological disorder (epilepsy, convulsions or convulsions) or psychosis;
• History of thyroid disease or thyroidectomy, absence of spleen, functional absence of spleen, and absence of spleen or splenectomy caused by any circumstance;
• Coagulation dysfunction (such as coagulation factor deficiency, coagulation disease, platelet abnormality) or obvious bruising or coagulation disorder diagnosed by doctors;
• Immunosuppressive therapy, cytotoxic therapy, inhaled corticosteroids (excluding corticosteroid spray therapy for allergic rhinitis, and surface corticosteroid therapy for acute non-complicated dermatitis) in the past 6 months;
• Long history of alcohol or drug abuse;
• Received blood products within 3 months prior to receiving the vaccine;
• Received other research drugs within 30 days prior to receiving the vaccine;
• Received live attenuated vaccine within 14 days prior to receiving the vaccine;
• Received subunit or inactivated vaccine within 7 days prior to receiving the vaccine;
• Onset of various acute or chronic diseases within 7 days prior to the study;
• Axillary temperature of >37.0℃ before inoculation of the vaccine;
• Those who are already pregnant (including a positive urine pregnancy test) or are breastfeeding, planning to become pregnant within 2 months;
• In the opinion of the investigator, the participants had any other factors that made them unsuitable to participate in the clinical trial.