This study is to evaluate the immunogenicity and safety of DTaP or DT given in children aged 6 years.

A phase 4 trial was conducted in Zhejiang Province aimed to evaluate the immunogenicity and safety of DTaP or DT in children aged 6 years. DTaP and DT are produced by Chengdu Institute of Biological Products Co., Ltd. Participants will be recruited and randomly divided into two groups to receive DTaP or DT in 1:1 ratio. Two blood samples were taken on Day 0 (pre-vaccination) and Day 28~42 (after-vaccination) for test antibody against pertussis, diphtheria and tetanus. Adverse events and serious adverse events were actively collected by staff within 28 days of vaccination.

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 with severe chronic diseases or acute episodes of chronic diseases; 9、Participants with infectious, suppurative and allergic skin diseases; 10、Other Participants whose physical conditions, as determined by the investigator, are not suitable for inclusion in clinical studies.