New Low-Dose tdap vaccine trial aims to boost protection with fewer side effects

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Age Requirement: volunteers aged 6 years and above * Provision of Legal Identification: volunteers and their legal guardians or appointed representatives must provide valid legal identification documents. * Informed Consent: participants, legal guardians, or appointed representatives of volunteers must have the capacity to understand the informed consent document and the research process, voluntarily participate, sign the informed consent form, and be able to comply with the requirements in the study as well as complete relevant visits on time. Exclusion Criteria: * Subjects whose physical examination, vital signs check, or laboratory test results are abnormal and have clinical significance, and are determined by the researcher to be unsuitable for participation in the clinical trial. * Subjects who have received any vaccine within 30 days (including the 30th day) before enrollment, or those who plan to receive other vaccines within 30 days (including the 30th day) after receiving the investigational vaccine. * Subjects who have experienced acute diseases (such as fever) or acute exacerbations of chronic diseases within 3 days before enrollment (including the third day). * Subjects who have had contact with patients clearly diagnosed with pertussis, diphtheria or tetanus within 30 days before enrollment. * Individuals who have been clinically diagnosed with diphtheria or tetanus within 10 years before enrollment, or with pertussis within 5 years; or those who have experienced paroxysmal spasmodic coughing for at least 14 days without fever within 5 years, and for which no other specific cause (such as influenza) can be identified, and have a history of exposure to pertussis or contact with confirmed cases. * Subjects who have been diagnosed with serious diseases that may interfere with the conduct or completion of the trial. * Subjects who have shown allergic reactions to any component of the trial vaccine (such as aluminum adjuvant) before enrollment, or have experienced severe allergic reactions, suspected severe allergies (such as Arthus reaction, anaphylactic shock, laryngeal edema, allergic purpura, local allergic necrotic reaction, etc.) or other serious adverse reactions (such as thrombocytopenic purpura, breathing difficulties, angioneurotic edema, widespread rash, brachial plexus neuritis, etc.) to any vaccine or drug before enrollment. * Subjects who have experienced convulsions, epilepsy, mental disorders before enrollment, or have a family history of such diseases, or have had severe brain diseases (such as hypoxic-ischemic encephalopathy, intracranial hemorrhage, cerebral palsy, intracranial tumors, cerebral infarction, stroke, etc.) before enrollment. * Subjects with coagulation disorders (such as deficiency of coagulation factors, coagulation diseases, and platelet abnormalities), or a history of bleeding disorders, or those with hereditary bleeding tendencies. * Individuals with primary or secondary immune function impairment, or those who have been receiving immunosuppressive therapy for a long time (such as long-term systemic glucocorticoid treatment, for example, using prednisone or similar drugs for two weeks or more continuously, but local use such as ointments, eye drops, inhalants or nasal sprays is allowed), or those who plan to use it during the trial. * Subjects who have had their spleen removed or undergone partial or complete removal of other vital organs (such as the liver, kidneys, lungs, pancreas, thyroid, stomach, intestines, and other vital organs) due to any cause. * Subjects who have donated blood or lost blood (≥ 400 ml) within 6 months before enrollment, received blood transfusion or used blood products, or plan to receive blood transfusion or use blood products during the trial. * Any investigational or unregistered products (drugs, biologics or devices) were used within 6 months before enrollment, or the subject plans to participate in or is currently participating in any clinical trial. * Subjects who may be unable to follow the trial procedures, abide by the agreement, or plan to permanently relocate from this area during the trial period, or be away from the local area for a long time during the scheduled visits. * Subjects deemed by the investigator to be unsuitable for participation in the study.