Immunogenicity and Safety of DTaP or DT Vaccine in 6 Year Old Children ( DTaP/DT )

Inclusion Criteria: * 1\. Participants aged ≥ 6 on the day of enrollment; 2. Informed consent should be signed and dated by the participants; 3. The participant's legal guardian is able to attend all planned follow-up visits and comply with all study procedures; 4. The participants have received 4 doses of acellular TDap vaccine and have not received any immunization agents related to diphtheria, tetanus, and pertussis in the past 3 years; 5. The participant has no diease history of pertussis, diphtheria or tetanus; 6. ≥ 14 days interval between the last vaccination; 7. Body temperature was ≤37.3℃. Exclusion Criteria: * 1、Being allergic to any component of vaccines ； 2、A history of severe allergic reactions to any vaccine (for example acute allergic reaction, angioneurotic edema, dyspnea, etc）； 3、Having a history or family history of convulsions, encephalopathy, psychosis, uncontrolled epilepsy and other progressive neurological diseases; 4、Participants are suffering from immunodeficiency, receiving immunosuppressant therapy (oral steroid hormones) during treatment for malignancy, or having low immunity due to HIV, or having congenital immune disorders in close family members; 5、Injection of non-specific immunoglobulin within 1 month before enrollment; 6、Participants are suffering from acute febrile diseases and infectious diseases; 7、A history of clearly diagnosed thrombocytopenia or other clotting disorders that may contraindicate subcutaneous injection; 8、Participants w…