a immuno-bridging and immunization schedules study of covid-19 vaccine (vero cell), inactivated

Conditions: Covid19

Summary: this trial is a randomized study to evaluate the immunogenicity of covid-19 vaccine (vero cell), inactivated and in population aged 60 years old and 3-17 years old with different schedules compared to that in population aged 18-59 years old with 2-dose schedule. and subjects in the same age are randomly assigned to different immunization schedule groups.

this trial is a randomized study to evaluate the immunogenicity of covid-19 vaccine (vero cell), inactivated and in population aged 60 years old and 3-17 years old with different schedules (d0,21,42, d0, 21,111,or d0,21,171)compared to that in population aged 18-59 years old with 2-dose schedule (d0,21). and subjects in the same age are randomly assigned to different immunization schedule groups.

Eligibility criteria:
inclusion criteria: * aged 3 years and above (after enrolled, subjects will be allocated according to age). * by asking for medical history and physical examination, the health condition judged by the investigators is well. * female subjects of childbearing age are not nursing or pregnant at the time of enrolment (negative urine pregnancy test) and have no family planning within the first 3 months after enrolment. effective contraceptive measures have been taken within 2 weeks before inclusion. * no vaccination history of covid-19 vaccine before enrollment. * be able and willing to complete the whole prescribed study plan. * with self-ability to understand the study procedures, the informed consent \& voluntarily sign an informed consent form and be able to comply with the requirements of the protocol. exclusion criteria: * confirmed cases, suspected cases or asymptomatic infections of sar-cov-2 infection (check "china disease prevention and control information system"). * has a history of sars, mers infection (self-report, on-site inquiry). * \>14-year-old subjects axillary temperature ≥37.3℃, ≤14-year-old subjects axillary temperature ≥37.5℃. * previous severe allergic reactions to vaccination (such as acute allergic reactions, urticaria, dyspnea, angioneurotic edema or abdominal pain) or allergy to known ingredients of inactivated sars-cov-2 vaccine have occurred. * with severe liver diseases, severe kidney diseases, uncontrollable hypertension (systolic blood pressure ≥160 mmhg, diastolic blood pressure ≥100 mmhg), diabetic complications, malignant tumors, various acute diseases, or acute attack period of chronic diseases. * has been diagnosed with congenital or acquired immune deficiency, hiv infection, lymphoma, leukemia or other autoimmune diseases. * has a history of convulsion, epilepsy, encephalopathy or mental illness or family history. * with congenital malformations or developmental disorders, genetic defects, severe malnutrition, etc. * has a history of coagulation dysfunction (e.g. coagulation factor deficiency, coagulation disease). * received immunotherapy or inhibitor therapy within 3 months (continuous oral or infusion for more than 14 days). * received live attenuated vaccinewithin 1 month before this vaccination, other vaccines are inoculated within 14 days before this vaccination. * received blood products within 3 months before enrolment. * received other research drugs within 6 months before enrolment. * other circumstances judged by investigators are not suitable for this clinical trial.

Keywords: sars-cov-2 sars-cov-2 vaccine coronavirus