10-year follow-up after a single acellular pertussis vaccination

Antibody Persistence and Safety and Immunogenicity of a Second Booster Dose 10 Years After a First Booster Vaccination With a Single Dose Vaccination of aP Vaccine in Adults: A Phase IV, Open-label, Non-randomized, Follow-up Study

This study will test whether a second booster dose of Pertagen® gives stronger protection than Adacel® and will measure antibody levels 10 years after the first booster in people who joined the original TDA202 trial.

Quick facts

• Phase: Phase 4
• Study type: Interventional
• Enrollment: 126 (estimated)
• Sex: All
• Sponsor: Mahidol University (Academic / other)
• Locations: 2 sites (Bangkok Noi, Bangkok Metropolis and 1 other locations)
• Trial ID: NCT06803524 on ClinicalTrials.gov

What this trial studies

This open-label, non-randomized phase IV follow-up invites participants from the phase II/III TDA202 trial back about 9.5–10 years after their first booster. Eligible participants who completed the original Day 336±28 visit will undergo screening, consent, medical history, and blood sampling. Those who receive a second booster will get either Pertagen® or Adacel® and will be monitored for safety and antibody responses. The primary focus is comparing immunogenicity and safety of the two boosters and documenting long-term antibody persistence from the original vaccines.

Who should consider this trial

Good fit: Ideal participants are adults who took part in the original TDA202 trial, received one of the three study vaccines and completed the Day 336±28 visit, are generally healthy, and can attend Bangkok study visits and give blood.

Not a fit: People who did not enroll in TDA202, who have received any pertussis vaccine since that trial, who are pregnant, or who have conditions preventing safe participation (for example active immunosuppression) would not be expected to benefit or would be ineligible.

Why it matters

Potential benefit: If successful, the results could show whether Pertagen® provides stronger or longer-lasting protection than Adacel®, helping guide future booster recommendations.

How similar studies have performed: Other studies have compared Tdap boosters and tracked antibody persistence over years, but direct 10-year data on the recombinant Pertagen® booster are limited so this follow-up addresses a relatively under-studied question.

Eligibility criteria

Inclusion Criteria:

A participant will be eligible for inclusion if ALL of the following apply at the time of screening:

1. Having participated in the initial TDA202 study, received a single dose of one of the 3 study vaccines, and completed 1-year follow-up visit;
2. Written informed consent is obtained prior to study entry;
3. Healthy, as established by pertinent medical history and physical examination;
4. Capable of complying with study procedures and willing to provide with a blood sample;
5. For women with childbearing potential (i.e., urine pregnancy test will not be performed in females who have undergone sterilisation, hysterectomy or who are post-menopausal), must have a negative urine pregnancy test at enrollment and willing to take reliable birth control measures for one month following vaccination.

Exclusion Criteria:

A participant with following criteria at screening will not be eligible for participation:

1. Having received any pertussis vaccine since completion of 1-year follow-up visit in the initial TDA202 study;
2. Having experienced physician-diagnosed pertussis since completion of 1-year follow-up visit in the initial TDA202 study prior to enrollment;
3. Pregnant or breast-feeding women or female participants who intend to become pregnant during study period;
4. History of any significant medical illness such as, but not limited to, immune deficiency, clinically significant psychiatric, hematologic, pulmonary, cardiovascular, or hepatic, renal, or endocrine disorder, splenic or thymic functional abnormality as determined by the investigator based on medical history and physical examination that may interfere with the participant's safety and evaluation of investigational vaccines in this study;
5. History of allergy or hypersensitivity to any vaccine (including its component);
6. History of any serious adverse event or neurological adverse event after vaccination;
7. History of receiving blood or blood component or immunoglobulin within 3 months prior to enrollment;
8. History of receiving immunosuppressive drugs or systemic corticosteroid (\>0.5 mg/kg of prednisolone or equivalent for more than 14 days) within 3 months prior to enrollment;
9. Having received any other vaccines within 28 days prior to enrollment (3 months for live- attenuated vaccines);
10. Plan to receive any other vaccine or plan to participate in another clinical trial with intervention during the study period;
11. A known bleeding diathesis or any condition that may be associated with a prolonged bleeding time resulting in a problem with intramuscular injection;
12. Any progressive or severe neurological disorder such as seizure disorder or Guillain-Barré syndrome;
13. History of any illness or clinical condition that, in the opinion of the investigator, might interfere with the results of the study or pose additional risk to the volunteers due to participation in the study
14. Fever as defined by body temperature ≥ 38°C at the time of enrollment (This is a temporary exclusion criterion).

Remark: If fever occurs at screening visit, the participant may be rescreened and enrolled at a later date at the discretion of the investigator, or withdrawn at the discretion of the investigator.

Where this trial is running

Bangkok Noi, Bangkok Metropolis and 1 other locations

• Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University — Bangkok Noi, Bangkok Metropolis, Thailand (Recruiting)
• Vaccine Trial Centre — Ratchathewi, Bangkok Metropolis, Thailand (Recruiting)

Study contacts

• Principal investigator: Punnee Pitisuttithum — Vaccine trial Centre
• Study coordinator: Punnee Pitisuttithum

Conditions Pertussis; TDA202; acellular pertussis vaccine; a second booster dose of Pertagen® as compared to Adacel®; antibody persistence at 10 years after vaccination; Pertagen; Boostagen; aP vaccine