Immunogenicity of a Combined Diphtheria-Tetanus-recombinant Acellular Pertussis (DTaP) Vaccine in Healthy Toddlers

Not Applicable

Completed

• Conditions: Pertussis Whooping Cough
• Interventions: Biological: Combined Diphtheria-Tetanus-recombinant acellular pertussis (DTaP) vaccine; Biological: Licensed DTaP

• Registration Number: NCT07213089
• Lead Sponsor: BioNet-Asia Co., Ltd.

Brief Summary

Recombinant acellular pertussis vaccines containing genetically detoxified Pertussis Toxin (PTgen) have been used for booster immunisation in children, adolescents and adults including pregnant women in Thailand. Three vaccines have been licensed in Thailand, a monovalent (aPgen) and two vaccines combined with tetanus and reduced diphtheria dose vaccines (TdaPgen and Tdapgen). To address the need for improved vaccines in younger children, a new recombinant pediatric DTaP vaccine (DTaPgen) containing 5 µg genetically detoxified Pertussis Toxin (PTgen) and 10 µg Filamentous Hemagglutinin (FHA) was developed and found safe and immunogenic in a phase II trial in children aged 3 years onwards.

The purpose of this study is to assess the immunogenicity and safety of this new pediatric formulation DTaPgen given as the first booster dose in healthy toddlers aged 15 to 36 months compared to a commercially available vaccine in Thailand.

Detailed Description

This is a phase II/III randomized, observer-blind, active-controlled study conducted in Thailand, children aged 15-36-month-old with a history of DTwP (n=240) or DTaP (n=50) priming were randomized 2:1 to receive a dose of recombinant DTaPgen or licensed DTaP-IPV. The aim of this study is to evaluate the safety and non-inferior immunogenicity of DTaPgen versus DTaP-IPV vaccine given as the first booster dose in toddlers.

Safety up to 1-year and vaccine antibody persistence will also be assessed for all children.

Study Timeline

• Study Start: 2020-07-13
• Primary Completion: 2022-04-04
• Study Completion: 2022-05-12
• Status Verified: 2025-10
• Study First Submitted: 2025-10-01
• Study First Submitted QC: 2025-10-01
• Last Update Submitted: 2025-10-01
• Study First Posted: 2025-10-08
• Last Update Posted: 2025-10-08

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 290

Inclusion Criteria

Participants will be eligible for inclusion if ALL of the following criteria are met at the time of screening:

1. 15 to 36 months of age at the time of vaccination.
2. Having completed the 3-dose DTwP or 3-dose DTaP vaccination (no interchange of DTwP and DTaP during primary immunization).
3. The parents or legal guardians of the participant are able to read and write.
4. The parents or legal guardians can provide written informed consent.
5. Healthy, as established by pertinent medical history and physical examination.

Exclusion Criteria

A participant with ANY of the following criteria at study entry will not be eligible for participation

1. History of any significant medical illness such as, but not limited to, immune deficiency, renal, hepatic, cardiovascular, or endocrine disorder as determined by the investigator based on medical history and physical examination.
2. History of allergy or hypersensitivity to any vaccine (including its component).
3. History of any serious adverse event or neurological adverse event after vaccination.
4. Having received only 1 or 2 doses of DTwP or DTaP (incomplete primary immunization) after birth until the study enrollment.
5. Having received the 4th dose DTwP or DTaP vaccination.
6. Having experienced a physician diagnosed diphtheria or tetanus or pertussis illness within 1 year prior to recruitment.
7. Receipt of any vaccine within 28 days prior to enrollment (3 months for live-attenuated vaccines).
8. Planning to receive tetanus, diphtheria, pertussis or planning to participate in another clinical trial during the study period (approximately 1 year).
9. Receipt of blood or blood component or immunoglobulin within 3 months prior to recruitment.
10. History of receiving any immunosuppressive drug or systemic corticosteroid (more than 0.5 mg/kg of prednisolone or equivalent for more than 14 days) within 3 months prior to recruitment.
11. Any bleeding disorder.
12. Any abnormality of splenic or thymic function.
13. Any progressive or severe neurological disorder such as seizure disorder or Guillain- Barre syndrome;
14. History of any illness including cognitive impairment and psychiatric disease that, in the opinion of the investigator, might interfere with the results of the study or pose additional risk to the participants due to participation in the study.
15. Fever as defined by body temperature more than 38 degree celsius at the time of enrollment (temporary exclusion criterion).

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Combined Diphtheria-Tetanus-recombinant acellular pertussis (DTaP) vaccine	Combined Diphtheria-Tetanus-recombinant acellular pertussis (DTaP) vaccine	Participants who having completed the 3 doses DTwP or 3-dose DTaP vaccination (on interchange of DTwP and DTaP during primary immunization) will be randomized to receive Acellular pertussis (DTaP) vaccine (0.5 ml) given by intramuscularly as a single dose
Licensed DTaP	Licensed DTaP	Participants who having completed the 3 doses DTwP or 3-dose DTaP vaccination (on interchange of DTwP and DTaP during primary immunization) will be randomized to receive Acellular pertussis (DTaP) vaccine (0.5 ml) given by intramuscularly as a single dose

Primary Outcome Measures

Name	Time	Method
Seroconversion rates of PT	At 28 days following vaccination	ELISA

Secondary Outcome Measures

Name	Time	Method
Percentages of participants with solicited post-immunization local and systemic reactions	During 7 days following vaccination	Self assessment by participant and data record from Diary Card
Percentages of participants with AEs	During 28 days following vaccination	AEs reported by participant
Percentages of participants with SAEs	Day 336 after vaccination	SAEs reported by participant
GMT antibody concentration to anti-PT neutralizing antibody	Day 336 after vaccination	CHO
GMT antibody concentration to DT, TT, PT and FHA	Day 336 after vaccination	ELISA
Seroprotection rates of Tetanus and Diphtheria	Day 336 after vaccination	ELISA
Seroconversion rates of FHA and anti-PT neutralizing antibody	Day 336 after vaccination	ELISA and CHO

Trial Locations

Locations (3)

Vaccine Trial Centre (VTC), Faculty of Tropical Medicine, Mahidol University; 🇹🇭 Bangkok, Bangkok, Thailand

Kamphaengphet Hospital; 🇹🇭 Kamphaeng Phet, Changwat Kamphaeng Phet, Thailand

Phaholpolpayuhasena Hospital; 🇹🇭 Kanchanaburi, Kanchanaburi, Thailand