Immunogenicity and Safety of Diphtheria, Tetanus, Pertussis (DTaP) Vaccine in 3-month-old Infants

Inclusion Criteria:

• Basic immune stage:

1. 3-month-old infants who can provide valid identification documents;
2. Infants should be born following a 37-42 weeks of pregnancy and have a birthweight that meets the standard (2500g ≤ body weight ≤ 4500g);
3. The legal guardian of the subject voluntarily agrees to their child'sparticipation in the trial and signs a written informed consent form;
4. The legal guardian of the subject has the ability to understand the trialprocedure and participate in all planned follow-up visits;
5. Has not received a vaccine containing the active ingredients of pertussis,diphtheria, tetanus combined vaccine;
6. Active control group 2 has not been vaccinated with any vaccine containing theactive ingredients of poliomyelitis vaccine or haemophilus influenzae vaccine;

• Enhanced immunity stage:

1. Infants and young children aged 18-24 months who have been enrolled in thisclinical trial at the age of 3 months;
2. Basic immunization has been completed in this clinical trial;
3. According to the researcher's opinion, the subjects and their legal guardians areable to comply with the requirements of the clinical trial protocol.

Exclusion Criteria:

• Basic immune stage:

1. Has a history of pertussis, diphtheria, or tetanus;
2. Has any history of severe allergies to vaccination in the past;
3. Allergy to any component of the experimental vaccine;
4. Has a history or family history of epilepsy, convulsions, encephalopathy, mentalillness;
5. Individuals with thrombocytopenia, any coagulation dysfunction, or undergoinganticoagulant therapy that may cause contraindications for subcutaneousinjection;
6. Suffering from serious congenital malformations or serious diseases that mayinterfere with the conduct or completion of the trial including but not limitedto: infant wheezing, Down syndrome, severe thalassemia, heart disease, liverdisease, kidney disease, diabetes, hereditary allergies, Guillain Barre syndrome,severe skin diseases, congenital or acquired immune defects (repeated perianalabscess), etc;
7. Has the history of severe abnormal production process, suffocation rescue,neurological damage, and current pathological jaundice;
8. Suffering from infectious diseases with clinical or serological evidence, such astuberculosis, hepatitis B, hepatitis C, or HIV infection confirmed by parents;
9. Within 3 months before to enrollment, has received systemic corticosteroidtreatment (any route of administration, ≥ 2mg/kg/day) for ≥ 14 days, such asprednisone, inhaled steroids such as budesonide, and fluticasone; Or being usingother immunosuppressants such as cyclosporine, tacrolimus, etc. beforeenrollment;
10. Within 3 months before enrollment，has received treatment with immunoglobulinand/or any blood products (except hepatitis B immunoglobulin) ;
11. Participating in or planning to participate in clinical trials of other drugs inthe near future;
12. According to the researcher's judgment, there are any other factors that are notsuitable for the subjects to participate in the clinical trial.

• Enhanced immunity stage:

1. Newly discovered severe allergic history to any previous vaccination;
2. Individuals with thrombocytopenia, any coagulation dysfunction, or undergoinganticoagulant therapy that may cause contraindications for subcutaneousinjection;
3. Suffering from serious congenital malformations or serious diseases that mayinterfere with the conduct or completion of the test, including but not limitedto: infant wheezing, Down syndrome, severe thalassemia, heart disease, liverdisease, kidney disease, diabetes, hereditary allergies, Guillain Barre syndrome,severe skin diseases, congenital or acquired immune defects (repeated perianalabscess), etc;
4. After completing basic immunization, subjects were vaccinated with other vaccinecontaining the active ingredients of pertussis, diphtheria, tetanus combinedvaccine before booster immunization;
5. Participating in or planning to participate in clinical trials of other drugs inthe near future;
6. According to the researcher's judgment, there are any other factors that are notsuitable for the subjects to participate in the clinical trial.