Maternal Immunization With Tetanus Toxoid, Reduced Diphtheria Toxoid, Reduced-dose (2 µg) Recombinant Pertussis Vaccine (TdaP2gen) and Its Effect on the Immune Response in Thai Infants up to 15-18 Months Old

Starting soon · Phase 4

Conditions studied: Pertussis, Diphtheria, Tetanus, Vaccine-Preventable Diseases

In brief

Pertussis remains a major global public health problem. In Thailand, pertussis vaccination is recommended during pregnancy at 20-32 weeks' gestation, together with routine childhood diphtheria-tetanus-pertussis vaccination administered as a primary series at 2, 4, and 6 months and booster doses at 18 months and 4-6 years of age. TdaP2gen, a newly developed combined tetanus, diphtheria, and recombinant genetically detoxified acellular pertussis vaccine containing 2 µg pertussis antigen, has shown favorable safety and non-inferior immunogenicity compared with existing pertussis vaccines. However, data on its use in pregnant women, transplacental antibody transfer, and potential immune interference in infants remain limited. This study aims to evaluate the safety and immunogenicity of TdaP2gen in pregnant women, assess antibody transfer to newborns, and investigate immune responses to tetanus, diphtheria, and pertussis following primary and booster pertussis-containing vaccinations in infants and toddlers, including comparisons between whole-cell and acellular pertussis-containing vaccine schedules.

Key facts

Study ID: NCT07621341
Run by: Chiang Mai University
People needed: 320
Starts: 2026-05-26
Expected to finish: 2030-12-31
Last updated by the study team: 2026-06-02

Who can join

Age: any, up to 45. Sex: any. Healthy volunteers: accepted.

You may qualify if…

Pregnant women aged 20 to 45 years
Healthy women in good general health
Gestational age between 20 and 32 weeks at enrollment
Singleton pregnancy
Low-risk, uncomplicated pregnancy as assessed by an obstetrician
No evidence of congenital anomalies identified on prenatal ultrasonographic screening
Willing to receive TdaP2gen vaccination and comply with collection of biological specimens as specified in the study protocol
Willing to allow their infant to receive either whole-cell pertussis-containing or acellular pertussis-containing combination vaccines according to the study randomization process, and to allow collection of biological specimens from the infant as specified in the study protocol
Able and willing to provide written informed consent prior to study participation

You may not qualify if…

Receipt of a tetanus-, diphtheria-, and chemical-detoxified pertussis-containing vaccine within 1 year prior to enrollment, or receipt of a tetanus-, diphtheria-, and genetic-detoxified pertussis-containing vaccine (TdaPgen) or genetic-detoxified acellular pertussis vaccine (aPgen) within 2 years prior to enrollment, including during the current pregnancy
History of laboratory-confirmed or clinically diagnosed pertussis infection within 1 year prior to enrollment
Presence of underlying medical conditions that may affect study outcomes, including but not limited to malignancy, autoimmune disease, immunodeficiency, epilepsy, hypertension, renal disease, or liver disease, as determined by the investigators
Pregnancy complications including hypertension (blood pressure >140/90 mmHg with proteinuria, or >150/100 mmHg regardless of proteinuria), current antihypertensive treatment, or preeclampsia
Endocrine disorders including hyperthyroidism, untreated hypothyroidism, or impaired glucose tolerance (e.g., type 1 or type 2 diabetes mellitus) diagnosed before or during pregnancy requiring treatment beyond dietary control
Severe or progressive neurological disorders, including epilepsy or a history of Guillain-Barré syndrome
Receipt of immunosuppressive agents, immunomodulatory agents, or high-dose systemic corticosteroids (>2 mg/kg/day, >20 mg/day, or equivalent) for more than 14 consecutive days within 6 months prior to enrollment
History of stillbirth, neonatal death, or recurrent spontaneous abortion (≥3 episodes).
Current medical or surgical treatment for prevention of preterm labor during the current pregnancy
Receipt of blood products, blood components, or immunoglobulins within 6 months prior to enrollment
Receipt of live attenuated vaccines within 3 months or any other vaccines within 28 days prior to enrollment
History of hypersensitivity or adverse reactions to study vaccines or vaccine components, or history of severe allergic reactions such as anaphylaxis to any vaccine
Behavioral, cognitive, or psychiatric conditions that, in the opinion of the investigator, may interfere with study participation or protocol compliance
History of smoking, alcohol abuse, or intravenous drug use that, in the opinion of the investigator, may interfere with study assessments or outcomes
Fever (body temperature ≥38.0°C or equivalent) within 72 hours prior to enrollment
Acute illness within 4 weeks prior to enrollment
Contraindications to intramuscular vaccination, including thrombocytopenia, coagulation disorders, hemophilia A or B, or use of anticoagulant therapy during pregnancy
Concurrent participation in another clinical study involving investigational vaccines or medications during participation in this study
Any medical or obstetric condition that, in the opinion of the study investigator, may interfere with study assessments or increase the risk to the mother or infant associated with study participation
Phase 2: Infants
Inclusion Criteria:
All infants born to pregnant women enrolled in Phase 1 who received TdaP2gen vaccination during pregnancy will be eligible for enrollment to Phase 2 study
Exclusion Criteria:
Gestational age <32 weeks (very preterm birth)
Birth weight <1,500 grams (very low birth weight)

Where it is running

Department of Pediatrics, Faculty of Medicine, Chiang Mai University — Chiang Mai, Thailand

Full record on ClinicalTrials.gov

Trial information comes from ClinicalTrials.gov and is refreshed daily. TrialsForMe does not provide medical care and does not run the studies it lists.