PertussisPhase 4M-PRIMENCT07621341

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

A Phase 4 study testing Maternal TdaP2gen vaccine, Infant Acellular Pertussis-containing Vaccine and Infant Whole-cell Pertussis-containing Vaccine in people with Pertussis and Diphtheria, run by Chiang Mai University at 1 site in Thailand.

Not yet recruiting

Opening soon. The study is approved but enrolment has not started yet. Sites may already take enquiries.

Sites and contacts

Official record

Search all trials

Trial summary

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… Read more about this study

Who is it for?: Ages 0 days to 45 yearsHealthy volunteers can take part
Conditions the study is for: Pertussis, Diphtheria, Tetanus
What is being tested?: Maternal TdaP2gen vaccine, Infant Acellular Pertussis-containing Vaccine and Infant Whole-cell Pertussis-containing Vaccine
Type of treatment: Vaccines
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 320 participants
Where: 1 siteThailand
Study dates: 26 May 2026to 31 Dec 2030
Phase: Phase 4

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

Ages 0 days to 45 years
All sexes
Healthy volunteers accepted
Child, Adult

Who may be able to join

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

Show all 10Show fewer

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
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

Who cannot join

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

Show all 26Show fewer

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
Gestational age <32 weeks (very preterm birth)
Birth weight <1,500 grams (very low birth weight)
Presence of major congenital anomalies identified after birth, including congenital abnormalities associated with genetic disorders, congenital infections, or severe structural abnormalities involving major organ systems such as the central nervous system, cardiovascular system, respiratory system, hepatobiliary and gastrointestinal system, or genitourinary system
Presence of severe neonatal medical conditions that may affect immune responses to study vaccines, including but not limited to severe respiratory distress, severe bronchopulmonary dysplasia, hypoxic ischemic encephalopathy (HIE), severe intraventricular hemorrhage (IVH), severe sepsis, non-physiologic jaundice, neonatal autoimmune thrombocytopenia, neurological disorders such as neonatal convulsions, necrotizing enterocolitis, or intracranial hemorrhage
Presence of conditions associated with increased risk of serious adverse reactions to study vaccines
Any medical condition or circumstance that, in the opinion of the study investigator, may interfere with study assessments or increase the risk to the participant associated with study participation

Trial locations and contacts

1 site in 1 country. Contact the study team or a site near you to ask about taking part.

Tavitiya Sudjaritruk, MD, PhD contact

+66-53-936471

tavitiya.s@cmu.ac.th

Thailand1 site

Department of Pediatrics, Faculty of Medicine, Chiang Mai University
Chiang Mai, 50200
Tavitiya Sudjaritruk, MD, PhD, +66-53-93-6471, tavitiya.s@cmu.ac.th

Other trials in Thailand

About this study

Official title: Maternal Immunization With Tetanus Toxoid, Reduced Diphtheria Toxoid, Reduced-dose (2 µg) Recombinant Pertussis Vaccine (TdaP2gen) and Its Effect on the Immune Response to Tetanus, Diphtheria and Pertussis in Thai Infants up to 15-18 Months Old: An Open-label, Randomized Controlled Trial

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.

Read the detailed description

Pertussis remains a major global public health problem. In Thailand, pertussis vaccination is recommended for all pregnant women at 20-32 weeks' gestation to protect newborns and young infants against pertussis during early life. In addition, combined diphtheria-tetanus-pertussis vaccination is routinely administered as a primary series at 2, 4, and 6 months of age, followed by booster doses at 18 months and 4-6 years of age.

TdaP2gen is a combined tetanus, diphtheria, and recombinant genetically detoxified acellular pertussis vaccine, containing 2 µg pertussis antigen, which has been recently developed. Previous clinical studies have demonstrated that TdaP2gen is safe and elicits non-inferior immune responses against pertussis compared with the 5 µg recombinant acellular pertussis vaccine (TdaP5gen) and the chemically inactivated Tdap vaccine. However, as TdaP2gen is a newly licensed vaccine in Thailand, data on its safety, immunogenicity in pregnant women, placental antibody transfer to infants, and potential immune interference with infant responses to routine pertussis-containing vaccines remain limited.

Therefore, this study aims to evaluate the safety and immunogenicity of TdaP2gen in pregnant women, assess transplacental antibody transfer to newborns, and investigate its impact on immune responses to diphtheria, tetanus, and pertussis following primary series and booster vaccination up to 15-18 months of age in infants and young children.

This study is divided into 3 phases as follows:

Phase 1 - Maternal and fetal phase: This phase will evaluate the immunogenicity and safety of TdaP2gen vaccination in pregnant women, including immune responses against tetanus, diphtheria, and pertussis, as well as the transplacental transfer of antibodies to newborns.

Phase 2 - Infant phase: This phase will assess immune responses to tetanus, diphtheria, and pertussis in infants following completion of the primary pertussis-containing vaccine series at 2, 4, and 6 months of age, comparing infants who receive whole-cell pertussis-containing vaccines (wP-containing vaccines) with those who receive acellular pertussis-containing vaccines (aP-containing vaccines).

Phase 3 - Toddler phase: This phase will evaluate immune responses to tetanus, diphtheria, and pertussis in toddlers after receiving a pertussis-containing booster vaccination at 15-18 months of age, comparing children who receive whole-cell pertussis-containing vaccines (wP-containing vaccines) with those who receive acellular pertussis-containing vaccines (aP-containing vaccines).

Conditions: Pertussis, Diphtheria, Tetanus, Vaccine-Preventable Diseases
Being tested: Maternal TdaP2gen vaccine, Infant Acellular Pertussis-containing Vaccine, Infant Whole-cell Pertussis-containing Vaccine
Keywords: Safety, Immunogenicity, Immune interference, Pregnant women, Newborns, Infants and young children, Pertussis-containing vaccine, Genetically-detoxified recombinant acellular pertussis vaccine
Medical subject headings: Whooping Cough, Diphtheria, Tetanus, Vaccine-Preventable Diseases

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

Maternal TdaP2gen vaccineBiological
A combined tetanus toxoid, reduced diphtheria toxoid, reduced-dose (2 µg) genetically-detoxified recombinant acellular pertussis vaccine (TdaP2gen)
Infant Acellular Pertussis-containing VaccineBiological
An infant acellular pertussis (aP)-containing vaccine
Infant Whole-cell Pertussis-containing VaccineBiological
An infant whole-cell pertussis (wP)-containing vaccine

Study groups in NCT07621341
Study group	Role	What they receive
Phase 1: Maternal TdaP2gen Group	Experimental	Maternal TdaP2gen Group Receives: Biological: Maternal TdaP2gen vaccine
Phase 2: Infant Acellular Pertussis-containing Vaccine Group	Experimental	Infant Acellular Pertussis-containing Vaccine Group Receives: Biological: Infant Acellular Pertussis-containing Vaccine
Phase 2: Infant Whole-cell Pertussis-containing Vaccine Group	Active comparator	Infant Whole-cell Pertussis-containing Vaccine Group Receives: Biological: Infant Whole-cell Pertussis-containing Vaccine

What is being measured

The primary outcome is the main question the study is designed to answer.

Phase 1: Maternal anti-pertussis toxin (PT), anti-filamentous hemagglutinin (FHA), anti-diphtheria toxoid, and anti-tetanus toxoid immunoglobulin G (IgG) geometric mean concentrations and seroresponse rates following TdaP2gen vaccination during pregnancy
Assessment of maternal anti-PT, anti-FHA, anti-diphtheria toxoid, and anti-tetanus toxoid IgG geometric mean concentrations and seroresponse rates before TdaP2gen vaccination, after vaccination, and at delivery
Measured: Pre-vaccination baseline, 4 weeks after vaccination (+/- 14 days), and at delivery
Phase 1: Cord blood anti-PT, anti-FHA, anti-diphtheria toxoid, and anti-tetanus toxoid IgG geometric mean concentrations and seroresponse rates at birth
Assessment of anti-PT, anti-FHA, anti-diphtheria toxoid, and anti-tetanus toxoid IgG geometric mean concentrations and seroresponse rates in cord blood collected at delivery among infants born to TdaP2gen vaccinated mothers
Measured: At delivery
Phase 1: Incidence of solicited local and systemic adverse events, serious adverse events, and adverse pregnancy outcomes of TdaP2gen vaccination during pregnancy
Assessment of solicited local and systemic adverse events as well as serious adverse events and adverse pregnancy outcomes among pregnant women receiving TdaP2gen vaccination during pregnancy.
Measured: From vaccination until delivery, assessed up to approximately 22 weeks post-vaccination.
Phase 2: Infant anti-PT, anti-FHA, anti-diphtheria toxoid, and anti-tetanus toxoid IgG geometric mean concentrations and seroresponse rates following primary diphtheria-tetanus-pertussis vaccination series
Assessment and comparison of anti-PT, anti-FHA, anti-diphtheria toxoid, and anti-tetanus toxoid IgG geometric mean concentrations and seroresponse rates between infants born to mothers receiving TdaP2gen vaccine during pregnancy who are randomized to receive either aP- or wP-containing vaccines as the primary vaccination series during infancy
Measured: Pre-primary series vaccination (within 2 months after birth) and post-primary series vaccination (at age 7 months +/- 14 days)
Phase 3: Infant anti-PT, anti-FHA, anti-diphtheria toxoid, and anti-tetanus toxoid IgG geometric mean concentrations and seroresponse rates following booster diphtheria-tetanus-pertussis vaccination
Assessment and comparison of anti-PT, anti-FHA, anti-diphtheria toxoid, and anti-tetanus toxoid IgG geometric mean concentrations and seroresponse rates between infants born to mothers receiving TdaP2gen vaccine during pregnancy who previously received either aP or wP-containing vaccines during the primary vaccination series and subsequently receive booster vaccination at 15-18 months of age
Measured: At 12 months of age (+/- 14 days), pre-booster vaccination, and 1 month after booster vaccination (+/- 14 days)

Secondary outcomes (7)

Phase 1: Maternal pertussis-neutralizing antibody geometric mean titers following TdaP2gen vaccination during pregnancy
Assessment of maternal pertussis-neutralizing antibody geometric mean titers in a subset of 40 pregnant women before TdaP2gen vaccination, after vaccination, and at delivery
Measured: Pre-vaccination baseline, 4 weeks after vaccination (+/- 14 days), and at delivery
Phase 1: Cord blood pertussis-neutralizing antibody geometric mean titers at birth
Assessment of pertussis-neutralizing antibody geometric mean titers in cord blood samples from newborns of a subset of 40 vaccinated pregnant women at delivery
Measured: At delivery
Phase 1: Knowledge and acceptability of pertussis and pertussis vaccine among pregnant women assessed using a structured questionnaire
Assessment of knowledge and acceptability of pertussis and pertussis vaccine among pregnant women using a structured questionnaire
Measured: Pre-vaccination baseline
Phase 2: Infant pertussis-neutralizing antibody geometric mean titers following primary diphtheria-tetanus-pertussis vaccination series
Assessment and comparison of pertussis-neutralizing antibody geometric mean titers in a subset of 40 infants born to mothers receiving TdaP2gen vaccine during pregnancy who are randomized to receive either aP- or wP-containing vaccines as the primary vaccination series during infancy
Measured: Pre-primary series vaccination (within 2 months after birth) and post-primary series vaccination (at age 7 months +/- 14 days)
Phase 2: Incidence of solicited local and systemic adverse events, unsolicited adverse events, and serious adverse events following the primary diphtheria-tetanus-pertussis vaccination series in infants
Assessment and comparison of the frequency and severity of solicited local and systemic adverse events, unsolicited adverse events, and serious adverse events following administration of aP- or wP-containing vaccines during the primary vaccination series in infants born to mothers receiving TdaP2gen vaccine during pregnancy
Measured: From the first dose of the primary diphtheria-tetanus-pertussis vaccination series until 1 month after completion of the primary vaccination series, assessed up to approximately 5 months
Phase 3: Infant pertussis-neutralizing antibody geometric mean titers following booster diphtheria-tetanus-pertussis vaccination
Assessment and comparison of pertussis-neutralizing antibody geometric mean titers in a subset of 40 infants born to mothers receiving TdaP2gen vaccine during pregnancy who previously received either aP or wP-containing vaccines during the primary vaccination series and subsequently receive booster vaccination at 15-18 months of age
Measured: At 12 months of age (+/- 14 days), pre-booster vaccination, and 1 month after booster vaccination (+/- 14 days)
Phase 3: Incidence of solicited local and systemic adverse events, unsolicited adverse events, and serious adverse events following booster diphtheria-tetanus-pertussis vaccination in infants
Assessment and comparison of the frequency and severity of solicited local and systemic adverse events, unsolicited adverse events, and serious adverse events following administration of aP or wP booster vaccination in infants born to mothers receiving TdaP2gen vaccine during pregnancy
Measured: From booster vaccination through 28 days after vaccination

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

26 May 202631 Dec 2030

First posted2 Jun 2026
Study start26 May 2026 (estimated)
Primary completion31 Dec 2029 (estimated)
Study completion31 Dec 2030 (estimated)

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Publications (2)Papers the sponsor has linked to this study.
Other trials for PertussisStudies of the same condition, open and under way.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design

Study type: Interventional
Phase: Phase 4
Primary purpose: Prevention
Allocation: Randomised
Intervention model: Parallel groups
Model description: This is a multi-stage maternal-infant interventional study. Phase 1 consists of an open-label, single-arm intervention phase enrolling 160 pregnant women receiving TdaP2gen vaccine. Infants born to enrolled mothers subsequently enter Phase 2, a parallel-group, open-label randomized controlled phase evaluating immune responses following the routine primary series of diphtheria-tetanus-pertussis vaccination during infancy using either whole-cell pertussis (wP)-containing or acellular pertussis (aP)-containing vaccines. In Phase 3, infants enrolled in Phase 2 continue in a longitudinal observational follow-up phase assessing immune responses after receiving booster diphtheria-tetanus-pertussis vaccination with either wP-containing or aP-containing vaccines at 15-18 months of age.
Masking: None (open label)
Enrolment: 320 participants (estimated)

IDs, dates and publications

ClinicalTrials.gov ID: NCT07621341
Sponsor's protocol ID: PED-2569-0103
Acronym: M-PRIME
Status last verified: May 2026
First submitted: 20 May 2026
Last updated: 2 Jun 2026
Results posted: No
Data monitoring committee: No
FDA-regulated drug: No
FDA-regulated device: No
Individual data sharing: No: There is not a plan to make individual participant data (IPD) available for this study.

Publications

Chokephaibulkit K, Puthanakit T, Chaithongwongwatthana S, Bhat N, Tang Y, Anugulruengkitt S, Chayachinda C, Anuwutnavin S, Lapphra K, Rungmaitree S, Tawan M, Andi-Lolo I, Holt R, Fortuna L, Kerdsomboon C, Yuwaree V, Mansouri S, Thai PH, Innis BL. Effective and safe transfer of maternal antibodies persisting two months postpartum following maternal immunization with different doses of recombinant pertussis-containing vaccines. Vaccine. 2024 Jan 12;42(2):383-395. doi: 10.1016/j.vaccine.2023.11.042. Epub 2023 Dec 7.
PubMed 38061956
Puthanakit T, Chokephaibulkit K, Anugulruengkitt S, Chaithongwongwatthana S, Phongsamart W, Wittawatmongkol O, Rungmaitree S, Tang Y, Kerdsomboon C, Yuwaree V, Fortuna L, Mansouri S, Pham HT, Bhat N, Innis BL. Infant Responses to Primary Immunization Following Vaccination in Pregnancy With Varying Doses of Recombinant Acellular Pertussis Vaccine Alone or Combined With Tetanus-Diphtheria. Pediatr Infect Dis J. 2025 Feb 1;44(2S):S56-S60. doi: 10.1097/INF.0000000000004609. Epub 2025 Feb 14.
PubMed 39951076