Immunogenicity and Safety of an Inactivated SARS-CoV-2 Vaccine Coadministered With Two Attenuated Vaccines

Inclusion Criteria: Aged 4 years old With legal guardian signing the informed consent Able to participate in all planned visits and comply with all research procedures (such as completing diary cards of adverse events and participating visits) With clear vaccination records including no SARS-CoV-2 vaccine history, with 1 varicella vaccine and 2 measles-containing vaccines history the last attenuated vaccine was administered ≥28 days ago, and other vaccines administered ≥14 days ago With an axillary temperature ≤37.5℃ at the time of vaccination Exclusion Criteria: First dose exclusion criteria: With SARS-CoV-2 infection in the last 3 months (any of the following conditions shall be met: positive nucleic acid test; positive antigen test; suspected SARS-CoV-2 infection symptoms of subject or close contacts) allergic to any substance of the vaccine or with a severe allergic reactions history of vaccines (such as acute allergic reactions, angioneurotic edema, breathing difficulties, etc.) Suffering uncontrolled epilepsy or progressive nerve system diseases, or with a history of Gribali syndrome With acute illness, severe or acute attack of chronic illness or fever With immunodeficiency or weakened immune system or being treated with immunosuppressant drugs (oral steroids) Received non specific immunoglobulin within 3 months Any situation that researchers thought that might influence the consequence of the clinical trial Second dose exclusion criteria： Occurrence of any serious adverse event that may be related to the previous dose of study vaccine Occurrence of systemic adverse reactions or allergic reactions with a severity level ≥ 3 recognized by researchers after vaccination Any new situations that fit the first dose exclusion criteria Any situation that researchers thought that might influence the consequence of the clinical trial